Nearly all commercial glasses fall into one of six basic categories or types. These categories are based on chemical composition. Within each type, except for fused silica, there are numerous distinct compositions.
Soda-lime glass is the most common (90% of glass made), and least expensive form of glass. It usually contains 60-75% silica, 12-18% soda, 5-12% lime. Resistance to high temperatures and sudden changes of temperature are not good and resistance to corrosive chemicals is only fair.
Lead glass has a high percentage of lead oxide (at least 20% of the batch by weight). It is relatively soft, and its refractive index gives a brilliance that may be exploited by cutting. It is more expensive than soda-lime glass and is favoured for electrical applications because of its excellent electrical insulating properties. Thermometer tubing and art glass are also made from lead-alkali glass, commonly called lead glass. This glass will not withstand high temperatures or sudden changes in temperature.
Borosilicate glass is any silicate glass having at least 5% of boric oxide in its composition. It has high resistance to temperature change and chemical corrosion. Not quite as convenient to fabricate as either lime or lead glass. Borosilicate's cost is moderate when measured against its usefulness. Pipelines, light bulbs, photochromic glasses, sealed-beam headlights, laboratory ware, and bake ware are examples of borosilicate products.
Aluminosilicate glass has aluminum oxide in its composition. It is similar to borosilicate glass but it has greater chemical durability and can withstand higher operating temperatures. Compared to borosilicate, aluminosilicates are more difficult to fabricate. When coated with an electrically conductive film, aluminosilicate glass is used as resistors for electronic circuitry.
Ninety-six percent silica glass is a borosilicate glass, melted and formed by conventional means, then processed to remove almost all the non-silicate elements from the piece. By reheating to 1200°C the resulting pores are consolidated. This glass is resistant to heat shock up to 900°C.
Fused silica glass is pure silicon dioxide in the non-crystalline state. It is very difficult to fabricate, so it is the most expensive of all glasses. It can sustain operating temperatures up to 1200°C for short periods.
The full article is available from the Corning Museum of Glass
Thursday, 29 January 2009
Saturday, 24 January 2009
Baoli compatibility with Bullseye
My tests have shown a variety of compatibilities from badly incompatible to apparently fully compatible. Each sheet will need to be tested against Bullseye, but this gives some indication of the extent of compatibility across the range. With my set of samples this indicated that 71% might be compatible, 23% showed stress and 6% were clearly incompatible.
All these were tested using Bullseye Tekta 1101.38 with a strip test. Again I stress each sheet of Baoli will need to be tested before use.
BB00-3 compatible
BB001 slight incompatibility
BB023-3 not compatible
BB024-3 slight incompatibility
BB031-3 compatible
BB032-3 slight incompatibility
BB059-3 compatible
BB063-3 compatible
BB071-3 compatible
BB072-3 compatible
BB074-3 compatible
BB081-3 compatible
BB082-3 compatible
BB091-3 slight incompatibility
BB101-3 slight incompatibility
BB211-3 compatible
BB0311-3 compatible
BB0410-3 compatible
BB0411-3 compatible
BB0412-3 compatible
BB0413-3 slight incompatibility
BB0414-3 compatible
BB513-3 slight incompatibility
BB0413-3 compatible
BB0414-3 compatible
BB0415-3 compatible
BB0416-3 compatible
BB049-3 compatible
BB0510-3 compatible
BB0511-3 compatible
BB0512-3 compatible
BB0513-3 compatible
BB058-3 compatible
BB711-3 slight incompatibility
BB712-3 compatible
BB812-3 slight incompatibility
BB911-3 not compatible
All these were tested using Bullseye Tekta 1101.38 with a strip test. Again I stress each sheet of Baoli will need to be tested before use.
BB00-3 compatible
BB001 slight incompatibility
BB023-3 not compatible
BB024-3 slight incompatibility
BB031-3 compatible
BB032-3 slight incompatibility
BB059-3 compatible
BB063-3 compatible
BB071-3 compatible
BB072-3 compatible
BB074-3 compatible
BB081-3 compatible
BB082-3 compatible
BB091-3 slight incompatibility
BB101-3 slight incompatibility
BB211-3 compatible
BB0311-3 compatible
BB0410-3 compatible
BB0411-3 compatible
BB0412-3 compatible
BB0413-3 slight incompatibility
BB0414-3 compatible
BB513-3 slight incompatibility
BB0413-3 compatible
BB0414-3 compatible
BB0415-3 compatible
BB0416-3 compatible
BB049-3 compatible
BB0510-3 compatible
BB0511-3 compatible
BB0512-3 compatible
BB0513-3 compatible
BB058-3 compatible
BB711-3 slight incompatibility
BB712-3 compatible
BB812-3 slight incompatibility
BB911-3 not compatible
Friday, 23 January 2009
Painting Tracing Lines on Glass
Testing the thickness of the paint
Using your smaller brush, load the paint into it, and practice applying black lines on a clear piece of scrap glass. If the paint seems too thick, add a very small amount of water.
Paint that does not stick
If the paint seems to bubble up or not adhere to portions of the glass, it is likely the glass is not clean. You can wash the glass, or simply add a little more water to the paint already on the glass and rub the paint over the glass with your finger or a small piece of paper towel. This will remove any dirt or film of oils on the glass.
Testing the amount of gum arabic
Allow your painted lines to completely dry. You will notice the dry paint has a chalky, opaque quality. Test your paint lines by rubbing a finger across a line. If it easily rubs off like powder, you need a bit more gum arabic. If you can't budge it and it seems hard and crusty, you have much too much gum in the mixture. Adjust the mixtures accordingly.
Inspecting the fired glass
When the glass is fired in the kiln, the paint (which is made of ground glass and various ground pigments) fuses with the glass. Too much gum in the mix, and the paint may bubble, sit on the surface, or do a few other ugly and unprofessional tricks to embarrass you. You have no choice but to start over with a new piece of glass. Getting the amount of gum arable right is crucial to the process.
If the lines are not consistent in colour depth, you can trace over them and fire again. This will darken the lines to a consistent level of colour.
Practice
Practice your tracing. This part of the art is like calligraphy - half the battle is learning to use your tool, the tracing brush, in one or two confident strokes. The quality of your trace line tells the world whether you are an amateur or an accomplished artist! You might even decide this is the only glass painting technique you will ever use. And you would be in good company. A good deal of Gothic stained glass relied solely on tracery for its embellishment and to good effect.
Using your smaller brush, load the paint into it, and practice applying black lines on a clear piece of scrap glass. If the paint seems too thick, add a very small amount of water.
Paint that does not stick
If the paint seems to bubble up or not adhere to portions of the glass, it is likely the glass is not clean. You can wash the glass, or simply add a little more water to the paint already on the glass and rub the paint over the glass with your finger or a small piece of paper towel. This will remove any dirt or film of oils on the glass.
Testing the amount of gum arabic
Allow your painted lines to completely dry. You will notice the dry paint has a chalky, opaque quality. Test your paint lines by rubbing a finger across a line. If it easily rubs off like powder, you need a bit more gum arabic. If you can't budge it and it seems hard and crusty, you have much too much gum in the mixture. Adjust the mixtures accordingly.
Inspecting the fired glass
When the glass is fired in the kiln, the paint (which is made of ground glass and various ground pigments) fuses with the glass. Too much gum in the mix, and the paint may bubble, sit on the surface, or do a few other ugly and unprofessional tricks to embarrass you. You have no choice but to start over with a new piece of glass. Getting the amount of gum arable right is crucial to the process.
If the lines are not consistent in colour depth, you can trace over them and fire again. This will darken the lines to a consistent level of colour.
Practice
Practice your tracing. This part of the art is like calligraphy - half the battle is learning to use your tool, the tracing brush, in one or two confident strokes. The quality of your trace line tells the world whether you are an amateur or an accomplished artist! You might even decide this is the only glass painting technique you will ever use. And you would be in good company. A good deal of Gothic stained glass relied solely on tracery for its embellishment and to good effect.
Thursday, 22 January 2009
Coloured Glass
Glass is coloured by (1) impurities in the batch ingredients, or(2) by one of three processes:
a. using a dissolved metallic oxide to impart a colour throughout
b. forming a dispersion of some substance in a colloidal state, and
c. suspending particles of pigments to form opaque colours.
A few historical examples:
The name of a colour was often used to describe a certain kind of glass, as in the Black bottle: a term for bottles of dark green or dark brown glass, the dark colour of which protected the contents from light. Often the "colour" black that appeared with reflected light was caused by the combination of iron, found in the sand used to make the batch, and the sulphur found in the smoke from the coal used to melt the batch. "Black" glass was first made in England in the mid-17th century.
Often, the name of the mineral added to give the glass its colour, as in Uranium glass (glass coloured with uranium oxide) was used. This brilliant yellow-green glass was first made in the 1830s.
Sometimes, a combination of both the additive and colour, as in Gold ruby glass was used. This is a deep red glass coloured by the addition of gold chloride to the batch. The method of making gold ruby glass was perfected shortly before 1679.
Optical terms can be used to describe the glass, as in dichroic glass. This is glass that is one colour when seen by reflected light and another colour when light shines through it (this is sometimes due to the presence of minute amounts of colloidal gold).
Iridescent glass is a deliberate effect (visually similar to the shimmering rainbow effect seen on the surface of soap bubbles, oil slicks, or fish scales). This is achieved by the introduction of metallic substances into the batch or by spraying the surface with stannous chloride or lead chloride and reheating it in a reducing atmosphere. On ancient glass, iridescence is caused by interference effects of light reflected from several layers of weathering products.
Iron can produce greens, iron and sulphur can produce ambers and browns, copper can produce light blues, cobalt produces very dark blue, manganese can produce shades of amethyst colour, tin can produce white, lead antimony can produce yellow and various metals produce reddish glasses.
A decolorizer is a substance (such as manganese dioxide or cerium oxide) used to remove or offset the greenish or brownish colour in glass that results from iron impurities in the batch or iron or other impurities in the pot or elsewhere in the production process.
The full article can be seen at the Corning Museum of Glass
a. using a dissolved metallic oxide to impart a colour throughout
b. forming a dispersion of some substance in a colloidal state, and
c. suspending particles of pigments to form opaque colours.
A few historical examples:
The name of a colour was often used to describe a certain kind of glass, as in the Black bottle: a term for bottles of dark green or dark brown glass, the dark colour of which protected the contents from light. Often the "colour" black that appeared with reflected light was caused by the combination of iron, found in the sand used to make the batch, and the sulphur found in the smoke from the coal used to melt the batch. "Black" glass was first made in England in the mid-17th century.
Often, the name of the mineral added to give the glass its colour, as in Uranium glass (glass coloured with uranium oxide) was used. This brilliant yellow-green glass was first made in the 1830s.
Sometimes, a combination of both the additive and colour, as in Gold ruby glass was used. This is a deep red glass coloured by the addition of gold chloride to the batch. The method of making gold ruby glass was perfected shortly before 1679.
Optical terms can be used to describe the glass, as in dichroic glass. This is glass that is one colour when seen by reflected light and another colour when light shines through it (this is sometimes due to the presence of minute amounts of colloidal gold).
Iridescent glass is a deliberate effect (visually similar to the shimmering rainbow effect seen on the surface of soap bubbles, oil slicks, or fish scales). This is achieved by the introduction of metallic substances into the batch or by spraying the surface with stannous chloride or lead chloride and reheating it in a reducing atmosphere. On ancient glass, iridescence is caused by interference effects of light reflected from several layers of weathering products.
Iron can produce greens, iron and sulphur can produce ambers and browns, copper can produce light blues, cobalt produces very dark blue, manganese can produce shades of amethyst colour, tin can produce white, lead antimony can produce yellow and various metals produce reddish glasses.
A decolorizer is a substance (such as manganese dioxide or cerium oxide) used to remove or offset the greenish or brownish colour in glass that results from iron impurities in the batch or iron or other impurities in the pot or elsewhere in the production process.
The full article can be seen at the Corning Museum of Glass
Wednesday, 21 January 2009
Copper Foil Splits
Copper foil splits often occur at tight inside curves. This is caused by the inability of the copper to stretch enough at the edges to make it around in tact.
There are at least two ways to deal with copper foil splits: avoid them or repair them.
Avoidance
One way to avoid splits at tight inside curves is to hand foil pieces that have these curves. When folding the foil from the edge to the sides of the glass, gently and progressively ease the foil toward the sides of the glass with your fingers rather than a hard tool. Do not try to make the fold all at once. Give the foil the chance to stretch into the curve through gentle persuasion.
Another way to avoid the splits is to use several short strips of foil at the tight inside curve. Apply each strip from one side around the edge to the other side of the glass. Overlap each strip until the inside curve is covered. Then you can cover the whole curve in the normal way with the copper foil. When the piece is foiled, you can then take a craft knife and trim the overlapped foils to match the edge of the long strip of foil. Or you can just trim the overlapped foil pieces to match the rest of the foil. Be aware that this increases the space required between the glass pieces as the foil is now effectively twice the thickness of regularly applied foil.
Repair
To repair splits in the foil at tight inside curves that have been foiled along with the rest of the piece, you take small pieces of foil and overlap at the splits.
When tinning these repairs, you need to take care that the heat from the iron does not loosen the adhesive so much that the foil pieces move.
There are at least two ways to deal with copper foil splits: avoid them or repair them.
Avoidance
One way to avoid splits at tight inside curves is to hand foil pieces that have these curves. When folding the foil from the edge to the sides of the glass, gently and progressively ease the foil toward the sides of the glass with your fingers rather than a hard tool. Do not try to make the fold all at once. Give the foil the chance to stretch into the curve through gentle persuasion.
Another way to avoid the splits is to use several short strips of foil at the tight inside curve. Apply each strip from one side around the edge to the other side of the glass. Overlap each strip until the inside curve is covered. Then you can cover the whole curve in the normal way with the copper foil. When the piece is foiled, you can then take a craft knife and trim the overlapped foils to match the edge of the long strip of foil. Or you can just trim the overlapped foil pieces to match the rest of the foil. Be aware that this increases the space required between the glass pieces as the foil is now effectively twice the thickness of regularly applied foil.
Repair
To repair splits in the foil at tight inside curves that have been foiled along with the rest of the piece, you take small pieces of foil and overlap at the splits.
When tinning these repairs, you need to take care that the heat from the iron does not loosen the adhesive so much that the foil pieces move.
Tuesday, 20 January 2009
Copper Foil Adhesive
The only technical purpose the adhesive on copper foil serves is to hold the foil on the glass until it is soldered. It is not intended to, and will not hold the piece together. You shouldn't ever rely on it to hold the pieces together. The heat from the soldering breaks down the adhesive, as well as time and chemicals like glass cleaner and flux. If you think that burnishing it harder will seal it, you are mistaken.If your foil is pulling away from an edge, you need to build up the solder on the edge, add wire if necessary, or a perimeter metal of some sort.
If you have a piece of glass that is "slipping" out, you may be trying to hold up too much weight by the foil. Put a perimeter metal on and hang the piece from a solder joint that extends into the design.
If you have a piece of glass that is "slipping" out, you may be trying to hold up too much weight by the foil. Put a perimeter metal on and hang the piece from a solder joint that extends into the design.
Monday, 19 January 2009
Soldering Copper Foil
Tip size
Soldering copper foil is ideally done with a smaller tip than for leaded glass. A 3/16" long taper tip is useful. Use the tip on edge rather than the flat side in order to minimize the iron's contact with the glass. Thus, the iron is held almost vertical. Foil heats up very fast and too much heat can crack the glass so the narrower the iron contact is the lower the risk.
Solder application
The solder is applied in one of two ways. The quickest method is to feed solder in on the thicker part of the shiny tip and let it flow down to the foil. The iron is held against the foil and pulled along the foil (which has been fluxed) at the rate that allows the solder being fed to the iron to produce a slightly rounded, shiny solder bead. Don't try and "float" the iron on top of the solder, be firmly down against the foil. This requires practice to match the speed of movement and the amount of solder fed to the iron.
Alternatively, you can do the patting method. This is easier to control and is done by soldering one tip-length, lifting the iron and soldering the next tip-length, barely re-heating the section just soldered.
Another variation is to place blobs of solder at regular intervals along the foiled and fluxed joint and then move the iron along the joint melting the blobs as you go. This avoids the tide marks at the cooling ends of the solder bead.
Soldering copper foil is ideally done with a smaller tip than for leaded glass. A 3/16" long taper tip is useful. Use the tip on edge rather than the flat side in order to minimize the iron's contact with the glass. Thus, the iron is held almost vertical. Foil heats up very fast and too much heat can crack the glass so the narrower the iron contact is the lower the risk.
Solder application
The solder is applied in one of two ways. The quickest method is to feed solder in on the thicker part of the shiny tip and let it flow down to the foil. The iron is held against the foil and pulled along the foil (which has been fluxed) at the rate that allows the solder being fed to the iron to produce a slightly rounded, shiny solder bead. Don't try and "float" the iron on top of the solder, be firmly down against the foil. This requires practice to match the speed of movement and the amount of solder fed to the iron.
Alternatively, you can do the patting method. This is easier to control and is done by soldering one tip-length, lifting the iron and soldering the next tip-length, barely re-heating the section just soldered.
Another variation is to place blobs of solder at regular intervals along the foiled and fluxed joint and then move the iron along the joint melting the blobs as you go. This avoids the tide marks at the cooling ends of the solder bead.
Wednesday, 14 January 2009
Reinforcement Materials and Methods
Variations in Reinforcement Materials and Methods
Be aware that every reinforcement situation is likely to vary. This is even more prevalent today with stained glass being more utilised in conditions which present varied structural situations.
External steel bars
There are many methods employed to provide reinforcement and a variety of mounting procedures. Surface reinforcement is probably best accomplished with flat cold-rolled galvanized steel bars either 3/8" or 1/2" in width by 1/8" thick. Since they are directly affixed to the solder joints of the section they disperse greater reinforcement than with 14 gauge copper tie wires attached to round or square bars which tend to stretch and consequently result in buckling from the sagging of the section.
Steels
Internal flat steel bars incorporated within the heart of the came are also of excellent service, especially in vertical instances. Horizontally they provide lateral reinforcement but likely no vertical resistance to sag.
Saddle bars
These are normally round or square steel bars that span the opening. The panel is inserted into the opening and blocked into place. The saddle bars are placed in the slots prepared in the sides or top and bottom of the opening, and the copper ties already soldered to the panel’s joints are twisted round the bar.
T bars
These are “T” shaped bars attached to the sides of the opening with the leg of the “T” facing outwards, The panel is supported by resting on the horizontal portion of the “T”. It is then fixed into place and cemented. These bars are normally made of alloys that do not corrode easily.
Be aware that every reinforcement situation is likely to vary. This is even more prevalent today with stained glass being more utilised in conditions which present varied structural situations.
External steel bars
There are many methods employed to provide reinforcement and a variety of mounting procedures. Surface reinforcement is probably best accomplished with flat cold-rolled galvanized steel bars either 3/8" or 1/2" in width by 1/8" thick. Since they are directly affixed to the solder joints of the section they disperse greater reinforcement than with 14 gauge copper tie wires attached to round or square bars which tend to stretch and consequently result in buckling from the sagging of the section.
Steels
Internal flat steel bars incorporated within the heart of the came are also of excellent service, especially in vertical instances. Horizontally they provide lateral reinforcement but likely no vertical resistance to sag.
Saddle bars
These are normally round or square steel bars that span the opening. The panel is inserted into the opening and blocked into place. The saddle bars are placed in the slots prepared in the sides or top and bottom of the opening, and the copper ties already soldered to the panel’s joints are twisted round the bar.
T bars
These are “T” shaped bars attached to the sides of the opening with the leg of the “T” facing outwards, The panel is supported by resting on the horizontal portion of the “T”. It is then fixed into place and cemented. These bars are normally made of alloys that do not corrode easily.
Wednesday, 7 January 2009
The Negotiating Framework for an Exhibition, 3
Proposals and Agreement
Make a proposal
Once you've had a chance to assess each other's position, you're ready for proposals and suggestions to be made. Mindful of how you have prioritised your list of 'achievements' you can start to 'trade', all the time looking for opportunities to offer things that are 'cheap' for one party but that are of real value to the other.
For example, a local authority or academic gallery that has an in-house photographer could offer the artist high-quality visual documentation of their exhibition that would otherwise cost the artist large amounts. An artist may offer to recommend the gallery as a good venue to peer artists in other areas or countries, to support the gallery's 'talent spotting' aspirations.
Trading and bargaining
After this period of exploration and testing, the trading and bargaining begins in earnest. Don't assume however, that this all has to happen at once, as you may do the testing and proposal-making some weeks or days before you sit down to bargain and finalise the arrangement. In general terms, ask for more than you expect to get and don't concede too much at the beginning because you've reduced your subsequent bargaining 'chips'.
In face-to-face discussions, be aware that body language speaks volumes - leaning back and folding your arms sends a signal that you're 'closed to discussion', whilst keeping eye contact and maintaining a normal sitting position says the reverse. It is an important to listen actively, to concentrate on what the other party is saying rather than waiting for them to finish so you can jump in and make your own points. Don't always feel obliged to bring in 'new' material when you speak, you can instead summarise what has been discussed as a way of 'buying time' to decide your next move. Silence is OK too, providing time to gather thoughts for another intervention.
Nowadays, negotiation is often done via email or telephone. It's better to avoid making curt or aggressive comments that can tend to turn a collaborative negotiation into a confrontational one. Don't reply to emails or unexpected telephone calls 'off the cuff'. Always refer to the paperwork or notes from previous communications.
An agreement cannot be reached until the parties get to a position they can both 'live with'. As a matter of course, this is generally somewhere between their respective starting points. Neither party should afterwards feel they were 'backed into a corner' or browbeaten into finalising the negotiation. If someone is pressing you to agree now it's usually because they will get more out of the arrangement than you will. So best not to.
When you've reached an agreement, write up your notes as a letter noting all the areas of agreement and send to the other party, asking them to confirm by signing, dating and returning to you a second copy that you have provided. Either artist or exhibition organiser can write up the agreement.
Susan Jones (used with permission)
Make a proposal
Once you've had a chance to assess each other's position, you're ready for proposals and suggestions to be made. Mindful of how you have prioritised your list of 'achievements' you can start to 'trade', all the time looking for opportunities to offer things that are 'cheap' for one party but that are of real value to the other.
For example, a local authority or academic gallery that has an in-house photographer could offer the artist high-quality visual documentation of their exhibition that would otherwise cost the artist large amounts. An artist may offer to recommend the gallery as a good venue to peer artists in other areas or countries, to support the gallery's 'talent spotting' aspirations.
Trading and bargaining
After this period of exploration and testing, the trading and bargaining begins in earnest. Don't assume however, that this all has to happen at once, as you may do the testing and proposal-making some weeks or days before you sit down to bargain and finalise the arrangement. In general terms, ask for more than you expect to get and don't concede too much at the beginning because you've reduced your subsequent bargaining 'chips'.
In face-to-face discussions, be aware that body language speaks volumes - leaning back and folding your arms sends a signal that you're 'closed to discussion', whilst keeping eye contact and maintaining a normal sitting position says the reverse. It is an important to listen actively, to concentrate on what the other party is saying rather than waiting for them to finish so you can jump in and make your own points. Don't always feel obliged to bring in 'new' material when you speak, you can instead summarise what has been discussed as a way of 'buying time' to decide your next move. Silence is OK too, providing time to gather thoughts for another intervention.
Nowadays, negotiation is often done via email or telephone. It's better to avoid making curt or aggressive comments that can tend to turn a collaborative negotiation into a confrontational one. Don't reply to emails or unexpected telephone calls 'off the cuff'. Always refer to the paperwork or notes from previous communications.
An agreement cannot be reached until the parties get to a position they can both 'live with'. As a matter of course, this is generally somewhere between their respective starting points. Neither party should afterwards feel they were 'backed into a corner' or browbeaten into finalising the negotiation. If someone is pressing you to agree now it's usually because they will get more out of the arrangement than you will. So best not to.
When you've reached an agreement, write up your notes as a letter noting all the areas of agreement and send to the other party, asking them to confirm by signing, dating and returning to you a second copy that you have provided. Either artist or exhibition organiser can write up the agreement.
Susan Jones (used with permission)
Tuesday, 6 January 2009
The Negotiating Framework for an Exhibition, 2
Beginnings
The opening
The first phase of a collaborative negotiation on an exhibition involves gathering as much information as possible, preferably well in advance of any meeting.
What do you want to achieve?
Before you start a negotiation, set out for yourself on paper what you want to achieve from the exhibition opportunity in terms of:
The opening
The first phase of a collaborative negotiation on an exhibition involves gathering as much information as possible, preferably well in advance of any meeting.
- Artists - research the gallery, how it programmes, what its current interests are, which other galleries 'look to' that one because they are good at picking interesting artists, etc.
- Gallery - research the artist, the context for their work, their peer network, their other projects, etc.
What do you want to achieve?
Before you start a negotiation, set out for yourself on paper what you want to achieve from the exhibition opportunity in terms of:
- Things you must achieve
- Things you intend to achieve
- Things you'd like to achieve
Discuss and explore
The first meeting provides an opportunity for artists and exhibition organiser to explore each other's needs, start to create a relationship and as part of this, for each to make tentative offers. Avoid stating your own preferences and ideas and instead use 'open questions' that create a space in which ideas can be explored, for example:
- What do you think about...?
- Is there something you'd like to suggest?
- From your experience, what do you find works well...?
- What other options could we look at?
Susan Jones (used with permission)
Monday, 5 January 2009
The Negotiating Framework for an Exhibition, 1
Introduction
In the world outside the arts, when someone offers something - a house for sale, a job, work from a trades person, a proposal of marriage even. This is generally the opening gambit in a negotiation process by which what has been offered will be discussed and in the process, either adjusted to create something of mutual benefit, or declined. But in the visual arts there is a tendency for the offer of an exhibition by a gallery to an artist to be taken at face value and either accepted or rejected. This doesn’t need to be so.
The intention here is to set out a mechanism for a collaborative negotiation. Through this the artist and gallery can share their respective aspirations and intentions for a proposed exhibition, and negotiate in order to arrive at a 'win-win' situation. One in which both feel comfortable about what has been agreed because they will both benefit. Importantly, they have also created a working relationship that can be built on in the future.
A collaborative negotiation is preferable to a competitive one where the parties are essentially out to get the best for themselves regardless of the wider implications. An unhappy relationship between artist and gallery tends to ricochet around the art world and does neither any good in the longer term.
Anyone inexperienced in negotiation techniques should get some professional guidance in advance. Artists could do this by contacting a training or professional development organisation. An arts organiser might ask for coaching from a line manager or senior colleague.
Susan Jones (used with permission)
In the world outside the arts, when someone offers something - a house for sale, a job, work from a trades person, a proposal of marriage even. This is generally the opening gambit in a negotiation process by which what has been offered will be discussed and in the process, either adjusted to create something of mutual benefit, or declined. But in the visual arts there is a tendency for the offer of an exhibition by a gallery to an artist to be taken at face value and either accepted or rejected. This doesn’t need to be so.
The intention here is to set out a mechanism for a collaborative negotiation. Through this the artist and gallery can share their respective aspirations and intentions for a proposed exhibition, and negotiate in order to arrive at a 'win-win' situation. One in which both feel comfortable about what has been agreed because they will both benefit. Importantly, they have also created a working relationship that can be built on in the future.
A collaborative negotiation is preferable to a competitive one where the parties are essentially out to get the best for themselves regardless of the wider implications. An unhappy relationship between artist and gallery tends to ricochet around the art world and does neither any good in the longer term.
Anyone inexperienced in negotiation techniques should get some professional guidance in advance. Artists could do this by contacting a training or professional development organisation. An arts organiser might ask for coaching from a line manager or senior colleague.
Susan Jones (used with permission)
Thursday, 18 December 2008
Glass painting tools
The tools needed for glass painting are few and relatively common, although the blender is specialised. The minimum you need are:
Glass palette –
a lightly etched glass sheet on which to grind and mix the paints
Palette knife –
a paint knife with a flexible metal blade used to mix and pile the paint
Tracing brush –
a thin and long-haired brush used to apply paint to glass. Sable is considered superior as it can hold a lot of paint allowing long lines.
Badger blender –
a wide and flat brush made of badger hair used to blend or evenly disperse a layer of paint on the glass, or to stipple a fine layer for a pin-hole effect
Stippler –
a round, thick brush used to apply wet paint and create a stippled matte.
Glass palette –
a lightly etched glass sheet on which to grind and mix the paints
Palette knife –
a paint knife with a flexible metal blade used to mix and pile the paint
Tracing brush –
a thin and long-haired brush used to apply paint to glass. Sable is considered superior as it can hold a lot of paint allowing long lines.
Badger blender –
a wide and flat brush made of badger hair used to blend or evenly disperse a layer of paint on the glass, or to stipple a fine layer for a pin-hole effect
Stippler –
a round, thick brush used to apply wet paint and create a stippled matte.
Tuesday, 16 December 2008
Enamels
In a discussion of art technology, enamel (or vitreous enamel, or porcelain enamel in American English) is the colourful result of fusion of metals carried in powdered glass to a substrate through the process of firing, usually between 750C and 850C. The powder melts and flows to harden as a smooth, durable vitreous coating on metal, glass or ceramic. It is often applied in a paste form and may be transparent or opaque when fired. Vitreous enamel can be applied to most metals.
Vitreous enamel has many excellent properties: it is smooth, hard, chemically resistant, durable, can take on long-lasting, brilliant colours, and cannot burn. Disadvantages are its tendency to crack or shatter when the substrate is stressed or bent.
Low firing enamels formulated for glass are forms of paint designed to fire between 550C and 600C which avoids the distortion of the glass that would occur with enamels designed for metals.
Vitreous enamel has many excellent properties: it is smooth, hard, chemically resistant, durable, can take on long-lasting, brilliant colours, and cannot burn. Disadvantages are its tendency to crack or shatter when the substrate is stressed or bent.
Low firing enamels formulated for glass are forms of paint designed to fire between 550C and 600C which avoids the distortion of the glass that would occur with enamels designed for metals.
Monday, 15 December 2008
Breaking Pliers
Description
The breaking pliers is a special stained glass tool that has smooth jaws that meet at the tip of the pliers. This enables the tool to reach over the top and bottom of the glass with only the tip coming into contact with the glass exactly against the score line.
Use
The pliers handles are held at a right angle to the score line. The edge of the glass needs to be close enough (within 20mm) to the score line in order to use this tool, as the tip of the jaw needs to be against the score line. It is used in lieu of your hands when the piece being broken off is too narrow to be comfortably grasped by hand. When bending the glass, the top jaw comes down flat against the surface of the glass (that's why we want the smooth jaw) and as more bending pressure is applied, lateral/pulling pressure is applied. This tool can also be used to groze the glass by carefully nibbling away the edge, but grozing pliers work better.
The breaking pliers is a special stained glass tool that has smooth jaws that meet at the tip of the pliers. This enables the tool to reach over the top and bottom of the glass with only the tip coming into contact with the glass exactly against the score line.
Use
The pliers handles are held at a right angle to the score line. The edge of the glass needs to be close enough (within 20mm) to the score line in order to use this tool, as the tip of the jaw needs to be against the score line. It is used in lieu of your hands when the piece being broken off is too narrow to be comfortably grasped by hand. When bending the glass, the top jaw comes down flat against the surface of the glass (that's why we want the smooth jaw) and as more bending pressure is applied, lateral/pulling pressure is applied. This tool can also be used to groze the glass by carefully nibbling away the edge, but grozing pliers work better.
Thursday, 11 December 2008
Cartooning for Acute Angles
When you are designing panels, you can prevent some leading difficulties. If you have shapes that join at acute angles, you can alter the design to make the leading simpler.
Say you have two balls touching. You can design the panel so the cut lines intersect or touch each other. This makes for extremely acute angles in the cutting of the cames. Two balls touching in the presentation drawing will not look the same if leaded that way. So if you make the edges of the balls just a few millimetres separate, the cames will pass each other, just touching, and so have the appearance of the presentation drawing, rather than the appearance of overlapping.
You separate the lines by the thickness of the came you will be using for that area. If you are using 6mm came, the cut lines should be just less than that distance apart. This will allow the cames to go around each shape and the flanges of the came will just overlap. This makes for quick leading and a clean appearance.
Say you have two balls touching. You can design the panel so the cut lines intersect or touch each other. This makes for extremely acute angles in the cutting of the cames. Two balls touching in the presentation drawing will not look the same if leaded that way. So if you make the edges of the balls just a few millimetres separate, the cames will pass each other, just touching, and so have the appearance of the presentation drawing, rather than the appearance of overlapping.
You separate the lines by the thickness of the came you will be using for that area. If you are using 6mm came, the cut lines should be just less than that distance apart. This will allow the cames to go around each shape and the flanges of the came will just overlap. This makes for quick leading and a clean appearance.
Tuesday, 9 December 2008
Handling Large Sheets
PreparationUse proper glass handling gloves.
Wear closed toe shoes, preferably with steel toe caps. This also allows you to set the glass on your toes prior to changing your grip to place the glass in the rack.
Clear the passage ways of all obstructions, whether on the floor or at the walls and door ways before moving any glass.
Lifting from horizontal
The transition between horizontal and vertical is important because the glass sheet can break if it does not have the proper support. However, there is a tried and true method for laying glass down and turning it over.
Rest the glass on the edge of the bench, half on, half sticking off. Support both sides of the sheet. Then pivot it to the horizontal, still resting the middle of the glass on the edge of the bench as your fulcrum. This provides support at the middle during the transition from vertical to the horizontal of the bench top.
CarryingTo carry large sheets of glass safely (for yourself and the glass), you need to support from below as well as the end. One gloved hand goes under the bottom and the other on the side. The glass is then carried vertically, with the edges at an angle. This is done in a manner so that the glass is on the side of your body with both palms are facing outwards. If there is a trip or other accident, the glass will be tipped away from the body. This sounds awkward, but is safe and easy when you get used to it. It also is the glazing industry standard method of carrying glass.
If the glass is too heavy to lift in this way, use suckers and get others to help.
If the glass breaks while carrying it just let it drop. Trying to catch or save it will lead to a hospital visit.
Always set the glass edges down on a cushioning material. This can be wood, linoleum, carpet, etc.
Transporting
Store, carry and transport glass as near to vertical as possible. You need to be careful when handling glass. In larger sheets it is very weak in a horizontal plane. It is strongest when it is in a vertical plane. (That’s why glass is always supposed to be shipped upright.)
If you are transporting a number of sheets, place paper between the sheets to avoid scratches and vibration damage or breakage. The glass should be tied tightly together, perferably on a rack. If you do not have a rack you can put into your vehicle, you can put the seat belts around the glass to keep it from flying forward in the event of an emergency stop.
Wear closed toe shoes, preferably with steel toe caps. This also allows you to set the glass on your toes prior to changing your grip to place the glass in the rack.
Clear the passage ways of all obstructions, whether on the floor or at the walls and door ways before moving any glass.
Lifting from horizontal
The transition between horizontal and vertical is important because the glass sheet can break if it does not have the proper support. However, there is a tried and true method for laying glass down and turning it over.
Rest the glass on the edge of the bench, half on, half sticking off. Support both sides of the sheet. Then pivot it to the horizontal, still resting the middle of the glass on the edge of the bench as your fulcrum. This provides support at the middle during the transition from vertical to the horizontal of the bench top.
CarryingTo carry large sheets of glass safely (for yourself and the glass), you need to support from below as well as the end. One gloved hand goes under the bottom and the other on the side. The glass is then carried vertically, with the edges at an angle. This is done in a manner so that the glass is on the side of your body with both palms are facing outwards. If there is a trip or other accident, the glass will be tipped away from the body. This sounds awkward, but is safe and easy when you get used to it. It also is the glazing industry standard method of carrying glass.
If the glass is too heavy to lift in this way, use suckers and get others to help.
If the glass breaks while carrying it just let it drop. Trying to catch or save it will lead to a hospital visit.
Always set the glass edges down on a cushioning material. This can be wood, linoleum, carpet, etc.
Transporting
Store, carry and transport glass as near to vertical as possible. You need to be careful when handling glass. In larger sheets it is very weak in a horizontal plane. It is strongest when it is in a vertical plane. (That’s why glass is always supposed to be shipped upright.)
If you are transporting a number of sheets, place paper between the sheets to avoid scratches and vibration damage or breakage. The glass should be tied tightly together, perferably on a rack. If you do not have a rack you can put into your vehicle, you can put the seat belts around the glass to keep it from flying forward in the event of an emergency stop.
Monday, 8 December 2008
Outside Curves
Outside curves are usually the easiest curve to break out. You do not have to worry about breaking the piece you wan to keep. The break, if it goes off the score line, will be away from the piece rather than into it.
Outside curves often have complimentary inside curves. So, on the principle of making the most difficult break first and the easiest last, the outside curve will be broken out last. Unless, of course, there is a straight line on the other side of the curve when the straight line would be the last, as it is the easiest score to break out.
Outside curves often have complimentary inside curves. So, on the principle of making the most difficult break first and the easiest last, the outside curve will be broken out last. Unless, of course, there is a straight line on the other side of the curve when the straight line would be the last, as it is the easiest score to break out.
Thursday, 4 December 2008
Preparing the Glass Paints
Paint
Measure about one tablespoon of black paint powder onto the center of your palette, With the edge of the palette knife, break up any clumps in the pigments. Grind the paint with the flat side of the palette knife until it feels and sounds smooth. Then mound the prepared powdered paint into a pile. Using the blade of the knife, pat the paint flat to about 1/8" thickness.
Gum Arabic
Then using the end of the palette knife, take some powdered gum arabic and, gently tapping the knife, sprinkle the gum over the surface of the paint. Use only enough to give the impression of a faint dusting of snow or sprinkling of salt. This step is crucial to the end result, as too much gum arabic makes removal of the paint from the glass with brushes and sticks difficult. Too much gum arabic can also cause the paint to bubble and splatter at firing temperatures. The correct amount may require some trial and error, but it is better to have less than more gum arabic.
Mixing
Blend the gum and paint together while dry. When thoroughly mixed, push into a mound, and make a valley in the center. Add about 1/2 teaspoon of water and with your palette knife, blend the pigment with the water. Add water and continue to blend until the paint is silky smooth and the consistency of thin yoghurt. Work the paint with a circular motion across the palette, then repeatedly "pile" the paint to the center of the palette.
Measure about one tablespoon of black paint powder onto the center of your palette, With the edge of the palette knife, break up any clumps in the pigments. Grind the paint with the flat side of the palette knife until it feels and sounds smooth. Then mound the prepared powdered paint into a pile. Using the blade of the knife, pat the paint flat to about 1/8" thickness.
Gum Arabic
Then using the end of the palette knife, take some powdered gum arabic and, gently tapping the knife, sprinkle the gum over the surface of the paint. Use only enough to give the impression of a faint dusting of snow or sprinkling of salt. This step is crucial to the end result, as too much gum arabic makes removal of the paint from the glass with brushes and sticks difficult. Too much gum arabic can also cause the paint to bubble and splatter at firing temperatures. The correct amount may require some trial and error, but it is better to have less than more gum arabic.
Mixing
Blend the gum and paint together while dry. When thoroughly mixed, push into a mound, and make a valley in the center. Add about 1/2 teaspoon of water and with your palette knife, blend the pigment with the water. Add water and continue to blend until the paint is silky smooth and the consistency of thin yoghurt. Work the paint with a circular motion across the palette, then repeatedly "pile" the paint to the center of the palette.
Wednesday, 3 December 2008
Glass painting Media
Mixing agents
These are the carriers that give "tooth" to the paints and are water-based or oil-based.
Common water-based media are:
These are the carriers that give "tooth" to the paints and are water-based or oil-based.
Common water-based media are:
- water & gum arabic,
- wine,
- sugar water,
- vinegar
Common oil-based media are:
- clove oil,
- lavender oil,
- damar varnish
Binders
Gum arabic
This natural gum (also called gum acacia) is a substance that is taken from two sub-Sharan species of the acacia tree, Acacia senegal and Acacua seyal. It is used primarily in the food industry as a stabiliser, but has had more varied uses in the past, including viscosity control in inks. For artists it is the traditional binder used in watercolour paint. It is sold in powder and liquid forms.
Dammar gum
This is obtained from the Dipterocarpaceae family of trees in India and East Asia, principally those of the genera Shorea, Balanocarpus, or Hopea. Most dammar gum is produced by tapping trees, however some is collected in fossilised form from the ground. The gum varies in colour from clear to pale yellow, while the fossilised form is grey-brown. It is used in foods, as a glazing agent, in the making of incense, varnishing and in other processes. Dammar was first introduced as a picture varnish in 1826 and is commonly referred to as Damar varnish
Tuesday, 2 December 2008
Glass Painting Terms
Tracing –
to paint a very thin line in one smooth, calligraphic stroke to define the basic shapes in the glass painting
Matting –
to apply a very thin coat of paint over the entire surface of the glass (usually
after tracing and firing) for further definition and highlighted details of the glass painting
Stippling –
removal of the matting to expose more glass and often used as a shading technique, using a pouncing motion, producing a pinhole effect
Stick-lighting –
removal of the matting to expose more glass and often used as a shading effect to create roundness and dimension in the glass painting
Firing –
the heating of the glass and paints to fuse the paints with the glass or stain the glass with the silver stains
to paint a very thin line in one smooth, calligraphic stroke to define the basic shapes in the glass painting
Matting –
to apply a very thin coat of paint over the entire surface of the glass (usually
after tracing and firing) for further definition and highlighted details of the glass painting
Stippling –
removal of the matting to expose more glass and often used as a shading technique, using a pouncing motion, producing a pinhole effect
Stick-lighting –
removal of the matting to expose more glass and often used as a shading effect to create roundness and dimension in the glass painting
Firing –
the heating of the glass and paints to fuse the paints with the glass or stain the glass with the silver stains
Monday, 1 December 2008
Laminated Glass
Laminated glass is a type of safety glass that holds together when shatered. In the event of breaking, it is held in place by an interlayer, typically of PVB, between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a characteristic "spider web" cracking pattern when the impact is not enough to completely pierce the glass.
Friday, 28 November 2008
The Glassy State
- Glass is a state of matter.
- Glasses combine some properties of crystals and some of liquids but are distinctly different from both.
- Glasses have the mechanical rigidity of crystals, but the random disordered arrangement of molecules that characterises liquids.
- Glasses are usually formed by melting crystalline materials at very high temperatures. When the melt cools, the atoms are locked into a random (disordered) state before they can form into a perfect crystal arrangement.
The complete description can be seen at the Corning Museum of Glass
Thursday, 27 November 2008
Smooth Solder Beads
Good smooth soldering occurs when the temperature of the iron is correct for the job and the solder being used.
The problem of bunched up solder or peaks as you lift the iron from the solder is caused by the iron being slightly too cool for the job and the solder being used. Looking at the conditions causing the problems may lead to a better solution.
If the problem is caused by the iron being slightly too cool to let the solder flow properly, this can be caused by a number of things.
The best possible soldering iron controller is a genuine temperature controlled iron, where the iron’s controller maintains the tip temperature by applying full power to the heater when the tip cools slightly, but otherwise just 'idles'. If you can't get (or afford) one of these, possibly the best would be to get a higher power iron or throw away the 'rheostat' or dimmer 'controller'.
If the problem still occurs, then use 60/40 solder – which melts and solidifies in a narrower range than 50/50 - or perhaps do the soldering in shorter 'bursts', letting the iron recover for a couple of minutes before starting again.
In any case you need to match the speed of movement and the speed of feeding the solder to the iron according to the capability of the iron to adequately melt the solder.
Also you have to ensure that the foil has been properly fluxed and tinned.
The problem of bunched up solder or peaks as you lift the iron from the solder is caused by the iron being slightly too cool for the job and the solder being used. Looking at the conditions causing the problems may lead to a better solution.
If the problem is caused by the iron being slightly too cool to let the solder flow properly, this can be caused by a number of things.
- If your iron is too low power, you may start out well and have the problem develop as you solder.
- If your iron is high enough power and you're using a 'rheostat' or dimmer controller, this has the effect of lowering the iron's power and the problem will occur as above.
- 50/50 (tin/lead) solder requires a hotter iron than 60/40 (tin/lead) solder to keep the molten metal flowing properly.
The best possible soldering iron controller is a genuine temperature controlled iron, where the iron’s controller maintains the tip temperature by applying full power to the heater when the tip cools slightly, but otherwise just 'idles'. If you can't get (or afford) one of these, possibly the best would be to get a higher power iron or throw away the 'rheostat' or dimmer 'controller'.
If the problem still occurs, then use 60/40 solder – which melts and solidifies in a narrower range than 50/50 - or perhaps do the soldering in shorter 'bursts', letting the iron recover for a couple of minutes before starting again.
In any case you need to match the speed of movement and the speed of feeding the solder to the iron according to the capability of the iron to adequately melt the solder.
Also you have to ensure that the foil has been properly fluxed and tinned.
Wednesday, 26 November 2008
Foil Pulling Away from Edges
If foil is pulling away from the glass on the perimeter of pieces, there are several things to remember.
Clean all the edges and surfaces just before foiling. This ensures there are no oils to interfere with the contact adhesive of the foil.
Avoid hand creams just before foiling as this increases the amount of oils getting onto the glass.
Remember that lots of heat breaks down the adhesive. So do not remain in one place too long. However the adhesive is not the element that keeps the foil attached to the glass in the long term.
Instead, think about whether the bead on the edge is thick enough to provide the rigidity required without relying on the adhesive of the foil.
Finally, think about whether an edging came would provide better support and finish to the piece.
Clean all the edges and surfaces just before foiling. This ensures there are no oils to interfere with the contact adhesive of the foil.
Avoid hand creams just before foiling as this increases the amount of oils getting onto the glass.
Remember that lots of heat breaks down the adhesive. So do not remain in one place too long. However the adhesive is not the element that keeps the foil attached to the glass in the long term.
Instead, think about whether the bead on the edge is thick enough to provide the rigidity required without relying on the adhesive of the foil.
Finally, think about whether an edging came would provide better support and finish to the piece.
Tuesday, 25 November 2008
Copper Foil Limitations
Unsupported windows
Windows without either rebar or internal support via Strongline or re-strip should not measure any more than 610mm in any dimension.
Flat work
It is not advisable to create anything over 1220mm (4 feet) by 1830mm (six feet) for a window installation even with re-inforcing bars. All such large copper foiled windows need an exterior piece of safety glass flush against the stained glass. Alternatively, split the window into smaller panels supported on “T” bar.Reinforcements
Anything over 610mm square normally requires internal reinforcements with either Strongline and/or restrip. Inserting long strips of either Strongline (copper plated steel) or restrip (thicker strips of copper) in between the copper foiled glass pieces to create a "spine" and then a "grid" of internal support is necessary when dispensing with rebar (horizontal lines of brass, steel, or other stiff metals attached to the panel for structural support).
Advantages
The huge advantage of copper foil is in the construction of three dimensional pieces and free hanging or standing pieces.
Subscribe to:
Posts (Atom)