Clarity of colour
When considering the representation of distance or depth you need to look for glass that is less pure. The colours that are muted or have a touch of white, blue or grey will provide a good representation of distance. The pure colours will appear more brilliant among the more muted colours.
This is where glass samples can be most useful. By holding them up to the light, you can see the effects one glass has on another and how one colour will appear among the others.
Saturday 2 October 2010
Tuesday 28 September 2010
Choosing Glass for a Harmonious Appearance - 1
There are at least two major elements in choosing glass: density and clarity. A third is the “hot/cool” effect of colours. The appropriate combination of these elements leads to a panel with bright or hot spots where you want them. You can create a dramatic image or a more restrained one with more gradual gradations of light without obvious bright or dark areas.
Density
Density relates to the amount of light the glass allows through. Clearly black is the most dense glass – allowing no light through. In general, glass can be divided into opalescent and transparent.
Opalescent glasses range from the very dense opaque to less dense translucent glass.
Transparent glasses have a variety of densities too, although almost always less dense than opalescent glass. The density of transparent glasses relates to the intensity of the colour and the texture of the glass.
Colour intensity
The intensity of the colour is related to the amount of light allowed through. The intensity is directly related to the saturation of the colour. A further effect on colour intensity is the thickness of the glass. If you look at a handmade sheet of glass with different thickness on one end to another end, you can see the gradation of the colour and the amount of light that comes through.
Glass Textures
The texture of the glass affects the density of the glass. A smooth glass will have less density as the light passes through without dispersion. As the glass becomes more textured, the light is more dispersed and so appears more dense.
Density
Density relates to the amount of light the glass allows through. Clearly black is the most dense glass – allowing no light through. In general, glass can be divided into opalescent and transparent.
Opalescent glasses range from the very dense opaque to less dense translucent glass.
Transparent glasses have a variety of densities too, although almost always less dense than opalescent glass. The density of transparent glasses relates to the intensity of the colour and the texture of the glass.
Colour intensity
The intensity of the colour is related to the amount of light allowed through. The intensity is directly related to the saturation of the colour. A further effect on colour intensity is the thickness of the glass. If you look at a handmade sheet of glass with different thickness on one end to another end, you can see the gradation of the colour and the amount of light that comes through.
Glass Textures
The texture of the glass affects the density of the glass. A smooth glass will have less density as the light passes through without dispersion. As the glass becomes more textured, the light is more dispersed and so appears more dense.
Friday 24 September 2010
Glass Breaking While Soldering
Some report breaking pieces of glass while soldering. This may happen more on pieces that have big differences in width or taper to thin points. What is happening is that the glass is being heated too much locally in relation to the rest of the piece.
The solution is to solder at a steady pace. This allows the solder to cool without transferring so much heat to the glass as to break it. Some recommend that you do not rest your soldering iron on the foil while soldering. However it is the solder which is the heat sink, so the effort of holding the iron above the foil is not really necessary if you move at a reasonable pace.
This means that you do not stop with the iron on the seam. It is best to solder in one continuous movement along the seam, leaving an even bead behind. Sometimes the bead is not even. This may be because of wider parts to the seam, or inadequate flux, or many other reasons. Do not try to repair this before going on to the rest of the seam as this builds up heat in the adjoining glass. Since glass cannot dissipate heat well, the glass breaks when the temperature differential between the hot and cold parts of the glass is too great. Instead, complete the soldering of the seam before coming back to it. This gives you time to decide why the bead is not as good as you want it to be. It also gives time for the heat to reduce and even out through the piece of glass.
As you become experienced you will find a pace that suits the kind of bead on the joint that you want to achieve. If the seam is too flat, slow your pace or increase the rate at which add the solder to the iron. If the seam has too big a bead, increase your pace or reduce the rate at which you feed the solder. It is also possible to consider other methods of soldering.
You also need consider the usual problems relating to cleanliness and insufficient flux. Sometimes the soldering iron is not hot enough, but you should notice this early as the solder will not be melting at its usual rate and will be grainy in appearance.
The solution is to solder at a steady pace. This allows the solder to cool without transferring so much heat to the glass as to break it. Some recommend that you do not rest your soldering iron on the foil while soldering. However it is the solder which is the heat sink, so the effort of holding the iron above the foil is not really necessary if you move at a reasonable pace.
This means that you do not stop with the iron on the seam. It is best to solder in one continuous movement along the seam, leaving an even bead behind. Sometimes the bead is not even. This may be because of wider parts to the seam, or inadequate flux, or many other reasons. Do not try to repair this before going on to the rest of the seam as this builds up heat in the adjoining glass. Since glass cannot dissipate heat well, the glass breaks when the temperature differential between the hot and cold parts of the glass is too great. Instead, complete the soldering of the seam before coming back to it. This gives you time to decide why the bead is not as good as you want it to be. It also gives time for the heat to reduce and even out through the piece of glass.
As you become experienced you will find a pace that suits the kind of bead on the joint that you want to achieve. If the seam is too flat, slow your pace or increase the rate at which add the solder to the iron. If the seam has too big a bead, increase your pace or reduce the rate at which you feed the solder. It is also possible to consider other methods of soldering.
You also need consider the usual problems relating to cleanliness and insufficient flux. Sometimes the soldering iron is not hot enough, but you should notice this early as the solder will not be melting at its usual rate and will be grainy in appearance.
Monday 20 September 2010
Temperature Rise Rates
I am always concerned when people recommend soaks on the way up in order to equalise temperatures. If the soak is required because the ramp rate is too fast, there are breakages going to happen sometime - maybe not now, maybe not tomorrow, but certainly sometime. If you need that extra time, add it into the schedule. E.g., a ramp rate of 200C from 20C to 520C with a 20 min soak could also be written as 176C/hr from 20C to 520C - both take 2.833 hours to achieve the same temperature. A controlled heating rate is preferable to one or more rapid rates with soaks.
I am also concerned about very rapid temperature rises after the bubble squeeze. The controllers often cannot adequately control such rapid rises. The rapid rise also often requires a higher target temperature to achieve the desired effect. This can mean that it is easier for bubbles - large and small - to form and rise to the surface during the overshoot of the target temperature. Temperature increases are about heat work - the combination of temperature and time. This means that you can achieve the desired result in two ways:
1- fast rise to high temperature or
2- Slow rise to lower temperature.
The second strategy may also require a longer soak at the target temperature than the one with a fast rise to a high temperature.
The aim in kiln work should be to achieve the effect you want at the lowest practical temperature. This is because glasses tend to change their characteristics more at higher temperatures than at lower temperatures.
I am also concerned about very rapid temperature rises after the bubble squeeze. The controllers often cannot adequately control such rapid rises. The rapid rise also often requires a higher target temperature to achieve the desired effect. This can mean that it is easier for bubbles - large and small - to form and rise to the surface during the overshoot of the target temperature. Temperature increases are about heat work - the combination of temperature and time. This means that you can achieve the desired result in two ways:
1- fast rise to high temperature or
2- Slow rise to lower temperature.
The second strategy may also require a longer soak at the target temperature than the one with a fast rise to a high temperature.
The aim in kiln work should be to achieve the effect you want at the lowest practical temperature. This is because glasses tend to change their characteristics more at higher temperatures than at lower temperatures.
Saturday 18 September 2010
Dams - Links to Tips
There are a number of tips on damming kiln formed glass scattered around the blog. This is an attempt to provide links to them.
Damming Options for Ovals
Description of Needling
Prevention of Needling
Damming Options for Irregular Shapes
How High Should the Dams Be?
Separators for Dams
Damming Options for Ovals
Description of Needling
Prevention of Needling
Damming Options for Irregular Shapes
How High Should the Dams Be?
Separators for Dams
Thursday 16 September 2010
Releases between the Glass and the Dam
An alternative to fibre papers or kiln wash separators between the dam and the glass is to use iridised glass. This of course, only works on pieces with straight lines on the sides. If you place the iridised side toward the fibre paper, you will get a clean release with a minimum of texture. If you do decide to use iridised glass as the release, you must not use Thinfire. It will cause awful pitting in the iridised glass.
Sunday 12 September 2010
Lining Dams
Dams should normally be lined with Thinfire and fibre paper to get the best release. If you are using fibre board that has not been hardened, you do not have to line, but you will get smoother edges if you do.
The lining papers should be about 3mm shorter than the expected final thickness of the finished panel. I find that 3mm paper against the dam provides the required standoff between the dam material and the glass. The lining of the fibre paper with Thinfire provides a smoother surface than just the fibre paper. Both of these liners should be the same height – 3mm less than the final height of the finished piece.
To calculate the expected final height you need to do a few calculations in the metric system. Weigh the glass in grams. Divide by specific gravity (2.5) to get the number of cubic centimeters. Divide the cc by the area enclosed by the dams in square centimeters. This will give the fraction or multiple of centimeters thick the glass is predicted to be.
Example:
The weight of glass = 500 gms
The specific gravity = 2.5
The area is 10cm by 10 cm = 100 square cm.
Divide 500gms (the weight) by 2.5 (the specific gravity) = 200 cubic centimeters. Divide 200 (the volume in cc) by 100 (the area) = 2 cm thick final piece for the amount of glass put into the pot.
This indicates the fibre paper should be 1.7cm high to allow enough space for the bullnose edge to form.
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| As described by Helios |
To calculate the expected final height you need to do a few calculations in the metric system. Weigh the glass in grams. Divide by specific gravity (2.5) to get the number of cubic centimeters. Divide the cc by the area enclosed by the dams in square centimeters. This will give the fraction or multiple of centimeters thick the glass is predicted to be.
Example:
The weight of glass = 500 gms
The specific gravity = 2.5
The area is 10cm by 10 cm = 100 square cm.
Divide 500gms (the weight) by 2.5 (the specific gravity) = 200 cubic centimeters. Divide 200 (the volume in cc) by 100 (the area) = 2 cm thick final piece for the amount of glass put into the pot.
This indicates the fibre paper should be 1.7cm high to allow enough space for the bullnose edge to form.
Wednesday 8 September 2010
Height of Dams
Dams can be of any height available, but if it is easy to adjust the height, you should consider the ease of working with the glass inside the dams and the possibility of anything falling off the dams onto the glass.
The dam should be higher than the glass in its un-fired state. It should be high enough to contain the moving glass should anything go wrong, so it cannot be the same height as the fibre paper liners – those being 3mm shorter than the glass is high. As a rule of thumb, when I have the choice, I would make the dams at least 6mm higher than the unfired glass. This allows you to handle the sheets of glass and any components without having to reach over high walls. It also ensures containment should anything go wrong.
The dam should be higher than the glass in its un-fired state. It should be high enough to contain the moving glass should anything go wrong, so it cannot be the same height as the fibre paper liners – those being 3mm shorter than the glass is high. As a rule of thumb, when I have the choice, I would make the dams at least 6mm higher than the unfired glass. This allows you to handle the sheets of glass and any components without having to reach over high walls. It also ensures containment should anything go wrong.
Saturday 4 September 2010
Damming Irregular Shapes
The assumption is that these pieces will be open-face thick fusings/castings rather than enclosed castings.
There are two basic types of dams: a shape cut from a single surrounding piece, or multiple pieces held in place.
Single piece dams
A large, thick fibre board with shape cut out will confine the glass. If very thick, you may need to weight the fibre board, as it is lighter than the glass.
Another variation is to use thick fibre paper cut out to shape and layered up to the desired height with stainless steel pins to hold the whole in place. This also may need to be weighted down. A variation on this is to place the whole on a fibre board and pin the layers of fibre paper into the fibre board to maintain the position of the fibre dams. This will not normally need weighting.
Multiple piece dams
If the shapes are not extreme, you can use pieces of fibre board or fibre paper backed up with kiln furniture, bits of broken kiln shelf or any other heavy material that will withstand the heat of fusing.
You can use thick fibre paper held in place with kiln furniture, if the piece is not thick. You do have to be careful that the glass does not float the fibre paper and run underneath, so about 10 mm is the maximum for this kind of damming. It also helps if this kind of dam is made larger than the glass – or alternatively the glass smaller than the dam. This allows the glass to flow out toward the dam, giving nice curved edges.
Moulds, stainless steel and other refractory materials can be specially made for shapes that will be repeated.
Note that all these variations will benefit from being lined with Thinfire backed up with fibre paper. This gives a smoother edge and also gives some cusioning between the dam and the glass.
There are two basic types of dams: a shape cut from a single surrounding piece, or multiple pieces held in place.
Single piece dams
A large, thick fibre board with shape cut out will confine the glass. If very thick, you may need to weight the fibre board, as it is lighter than the glass.
Another variation is to use thick fibre paper cut out to shape and layered up to the desired height with stainless steel pins to hold the whole in place. This also may need to be weighted down. A variation on this is to place the whole on a fibre board and pin the layers of fibre paper into the fibre board to maintain the position of the fibre dams. This will not normally need weighting.
Multiple piece dams
If the shapes are not extreme, you can use pieces of fibre board or fibre paper backed up with kiln furniture, bits of broken kiln shelf or any other heavy material that will withstand the heat of fusing.
You can use thick fibre paper held in place with kiln furniture, if the piece is not thick. You do have to be careful that the glass does not float the fibre paper and run underneath, so about 10 mm is the maximum for this kind of damming. It also helps if this kind of dam is made larger than the glass – or alternatively the glass smaller than the dam. This allows the glass to flow out toward the dam, giving nice curved edges.
Moulds, stainless steel and other refractory materials can be specially made for shapes that will be repeated.
Note that all these variations will benefit from being lined with Thinfire backed up with fibre paper. This gives a smoother edge and also gives some cusioning between the dam and the glass.
Monday 30 August 2010
Coating Metal Moulds
Most metal moulds are stainless steel as it spalls less while at forming temperatures. The techniques here can be applied to any metal, although spalling will be a common occurrence on any metal other than high grade stainless steel.
On many single curve moulds, such as a partial cylinder, you can just lay fibre paper over the form and place the glass on top of that.
Metal moulds that have more complex shapes require a separator that will conform to those shapes. Applying liquid kiln wash requires you to heat the steel to somewhere between 150 and 200C before applying the kiln wash. Any hotter and the kiln wash will boil off on contact, leaving an uneven coating.
The kiln wash can be applied with a brush or by spraying. Spraying gives a smoother less streaky application. After giving the mould the first coat, return the mould to the kiln and re-heat the mould. Repeat this until you have covered the whole mould with a thin layer of separator. Be careful and avoid applying too much kiln wash at once, as that will cause the separator to run and reveal bare spots on the mould, causing you to need to clean and begin again.
On many single curve moulds, such as a partial cylinder, you can just lay fibre paper over the form and place the glass on top of that.
Metal moulds that have more complex shapes require a separator that will conform to those shapes. Applying liquid kiln wash requires you to heat the steel to somewhere between 150 and 200C before applying the kiln wash. Any hotter and the kiln wash will boil off on contact, leaving an uneven coating.
The kiln wash can be applied with a brush or by spraying. Spraying gives a smoother less streaky application. After giving the mould the first coat, return the mould to the kiln and re-heat the mould. Repeat this until you have covered the whole mould with a thin layer of separator. Be careful and avoid applying too much kiln wash at once, as that will cause the separator to run and reveal bare spots on the mould, causing you to need to clean and begin again.
Thursday 26 August 2010
Cleaning Glass
Glass with dust, oil or other residues promotes devitrification. So first try to remove any excess of these.
Cutting without oil can avoid introducing more oils. Specially formulated cuttings fluids are available that are not oil.
Wash with only a few drops of washing up liquid of the kind without additives to keep you hands soft, or smell good. If there are soap bubbles on top of the water, you are using too much soap.
Window cleaning products are not usually appropriate, especially if they contain ammonia. A few products do not have additives that promote devitrification. One that works well for me is the Bohle aerosol cleaner (but not the concentrate).
Be careful about your rinsing water. If it has mineral salts in it, it can form nucleation points for devit.
Polish dry using plain paper towels or microfiber cloths. Change frequently and wash without softeners.
If you are grinding the edges, clean immediately before any part dries to avoid the powdered glass filling the scratches caused by grinding. Some put the ground pieces into a bowl of water immediately to keep the edges wet until cleaning can be done.
Cutting without oil can avoid introducing more oils. Specially formulated cuttings fluids are available that are not oil.
Wash with only a few drops of washing up liquid of the kind without additives to keep you hands soft, or smell good. If there are soap bubbles on top of the water, you are using too much soap.
Window cleaning products are not usually appropriate, especially if they contain ammonia. A few products do not have additives that promote devitrification. One that works well for me is the Bohle aerosol cleaner (but not the concentrate).
Be careful about your rinsing water. If it has mineral salts in it, it can form nucleation points for devit.
Polish dry using plain paper towels or microfiber cloths. Change frequently and wash without softeners.
If you are grinding the edges, clean immediately before any part dries to avoid the powdered glass filling the scratches caused by grinding. Some put the ground pieces into a bowl of water immediately to keep the edges wet until cleaning can be done.
Sunday 22 August 2010
Moving Pieces
To keep pieces from moving about as you solder them, use pins or nails to keep them in place. The best is to assemble the whole panel and then keep them in place with a frame or lots of nails/pins around the outside. This keeps pieces from moving and also keeps the panel to the original size.
The type of nail or pin will depend on the work board you are using. Softer boards allow push pins of various sorts to be used. Harder boards will need nails.
If you don’t like assembling the whole before soldering, you can confine the pieces you are currently soldering with nails/pins in the same fashion as for the whole panel.
It also helps to do a little tack soldering before the process of running a bead begins. A small amount of solder on the copper foil where pieces join will keep the pieces in exact alignment while you are running a bead.
The type of nail or pin will depend on the work board you are using. Softer boards allow push pins of various sorts to be used. Harder boards will need nails.
If you don’t like assembling the whole before soldering, you can confine the pieces you are currently soldering with nails/pins in the same fashion as for the whole panel.
It also helps to do a little tack soldering before the process of running a bead begins. A small amount of solder on the copper foil where pieces join will keep the pieces in exact alignment while you are running a bead.
Wednesday 18 August 2010
Devitrification of Edges
Devitrification often occurs on the edges of glass, and can be seen as a thin line of devitrification -often looking like smudges that won't wipe off - where the edge has flattened during the fusing. There are some ways to avoid this.
Avoid grinding if at all possible.
If you must grind, use fine heads/grits. Then clean immediately before any part of the glass dries. You may need to clean part of the glass piece before the grinding is complete to avoid any drying of the powder on the edge of the glass.
Clean well with a minimum of soap and rinse with water that does not have a lot of minerals in it. Polish well with plain paper towels or frequently changed microfiber cloths.
Window cleaning products are not usually appropriate, especially if they contain ammonia.
Avoid introducing oils from the cutter by scoring with a dry cutter or use a specially devised cutting fluid. Cleaning solutions that have additives to be kind to hands or scents should be avoided.
The edges of some glasses devitrify more easily than others. If this continues to be the case after all cleaning efforts have failed, then use a devitrification spray, but continued cleaning is still necessary. There are no short cuts in cleaning.
Avoid grinding if at all possible.
If you must grind, use fine heads/grits. Then clean immediately before any part of the glass dries. You may need to clean part of the glass piece before the grinding is complete to avoid any drying of the powder on the edge of the glass.
Clean well with a minimum of soap and rinse with water that does not have a lot of minerals in it. Polish well with plain paper towels or frequently changed microfiber cloths.
Window cleaning products are not usually appropriate, especially if they contain ammonia.
Avoid introducing oils from the cutter by scoring with a dry cutter or use a specially devised cutting fluid. Cleaning solutions that have additives to be kind to hands or scents should be avoided.
The edges of some glasses devitrify more easily than others. If this continues to be the case after all cleaning efforts have failed, then use a devitrification spray, but continued cleaning is still necessary. There are no short cuts in cleaning.
Saturday 14 August 2010
Effect of Variations in Size on Bead Annealing
When annealing beads with varying thicknesses, I apply a rule of thumb to be safe.
I take the difference between the thickest and the thinnest part and add that to the thickest part to get the diameter at which I should anneal.
So a bead with a thickest part being 8mm and the thinnest 2mm, gives a difference of 6mm which I add to the 8mm (thickest) part giving 14mm as the diameter to which I anneal.
I take the difference between the thickest and the thinnest part and add that to the thickest part to get the diameter at which I should anneal.
So a bead with a thickest part being 8mm and the thinnest 2mm, gives a difference of 6mm which I add to the 8mm (thickest) part giving 14mm as the diameter to which I anneal.
Tuesday 10 August 2010
Annealing Beads of different sizes and shapes
It is possible to anneal beads of different sizes and shapes at the same time, if you anneal for the beads which require the most care. It will not matter for the smaller beads or easier shapes if they are annealed longer than the minimum requirement.
Friday 6 August 2010
Effect of Shape on Bead Annealing
The shape of the bead has significant effects on the annealing time required. This is because the shape has an effect on the speed at which the centre can cool. Spheres have the most even transmission of heat, because the heat can radiate equally in all directions. Cylinders are more restricted in heat radiation because they can radiate heat from the circumference but not so effectively along the length. Flat shapes can radiate heat in only two directions, making them the most difficult to anneal.
As indicated, spheres can be annealed most quickly. The annealing schedules given in this blog apply to spheres as this is the most common form for beads.
Cylinders which by definition are longer than the diameter need to be annealed at two thirds the rate of spheres. So, from the tables you choose the annealing rate for a piece 1.5 times larger than the diameter of your cylinder.
Flat shapes require the most care in annealing so you should choose the rate that is three times the thickness of the piece you are annealing.
These cautions will help to adequately anneal your beads, what ever their shape.
As indicated, spheres can be annealed most quickly. The annealing schedules given in this blog apply to spheres as this is the most common form for beads.
Cylinders which by definition are longer than the diameter need to be annealed at two thirds the rate of spheres. So, from the tables you choose the annealing rate for a piece 1.5 times larger than the diameter of your cylinder.
Flat shapes require the most care in annealing so you should choose the rate that is three times the thickness of the piece you are annealing.
These cautions will help to adequately anneal your beads, what ever their shape.
Monday 2 August 2010
Bead Annealing Schedules for Spectrum Beads
Bead Annealing Schedules for Spectrum Beads
This table is based on James Kirwin’s work on bead making with variations. This is for cold beads being heated for a secure anneal.
Up to 10mm dia.: afap to 520C, 30 mins; anneal at 300C/hr to 370C; afap to 40C
12mm dia.: 1000C/hr to 520C,30mins; anneal at 210C/hr; 600C/hr to 40C
14mm dia.: 1000C/hr to 520C, 30mins; anneal at 155C/hr; 460C/hr to 40C
16mm dia.: 950C/hr to 520C, 30mins; anneal at 120C/hr; 350C/hr to 40C
18mm dia.: 740C/hr to 520C, 30mins; anneal at 94C/hr; 280C/hr to 40C
20mm dia.: 600C/hr to 520C, 30mins; anneal at 75C/hr; 230C/hr to 40C
22mm dia.: 500C/hr to 520C, 30mins; anneal at 62C/hr; 185C/hr to 40C
24mm dia.: 420C/hr to 520C, 30mins; anneal at 53C/hr; 155C/hr to 40C
30mm dia.: 270C/hr to 520C, 36mins; anneal at 33C/hr; 100C/hr to 40C
38mm dia.: 165C/hr to 520C, 39mins; anneal at 21C/hr; 60C/hr to 40C
50mm dia.: 95C/hr to 520C, 46mins; anneal at 12C/hr; 36C/hr to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
This table is based on James Kirwin’s work on bead making with variations. This is for cold beads being heated for a secure anneal.
Up to 10mm dia.: afap to 520C, 30 mins; anneal at 300C/hr to 370C; afap to 40C
12mm dia.: 1000C/hr to 520C,30mins; anneal at 210C/hr; 600C/hr to 40C
14mm dia.: 1000C/hr to 520C, 30mins; anneal at 155C/hr; 460C/hr to 40C
16mm dia.: 950C/hr to 520C, 30mins; anneal at 120C/hr; 350C/hr to 40C
18mm dia.: 740C/hr to 520C, 30mins; anneal at 94C/hr; 280C/hr to 40C
20mm dia.: 600C/hr to 520C, 30mins; anneal at 75C/hr; 230C/hr to 40C
22mm dia.: 500C/hr to 520C, 30mins; anneal at 62C/hr; 185C/hr to 40C
24mm dia.: 420C/hr to 520C, 30mins; anneal at 53C/hr; 155C/hr to 40C
30mm dia.: 270C/hr to 520C, 36mins; anneal at 33C/hr; 100C/hr to 40C
38mm dia.: 165C/hr to 520C, 39mins; anneal at 21C/hr; 60C/hr to 40C
50mm dia.: 95C/hr to 520C, 46mins; anneal at 12C/hr; 36C/hr to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
Friday 30 July 2010
Bead Annealing Schedule for Effetre Beads
This table is based on James Kirwin’s work on bead making with variations. This is for cold beads being heated for a secure anneal.
Up to 10mm dia.: afap to 530C, 30 mins; cool at 280C/hr to 360C; 840C to 40C.
12mm dia.: Go at 1000C/hr to 530C, 30mins.; cool at 194C/hr to 360C; at 580C/hr to 40C
14mm dia.: Go at 1000C/hr to 530C, 30mins.; cool at 142C/hr to 360C; at 425C/hr to 40C
16mm dia.: Go at 870C/hr to 530C, 30mins.; cool at 109C/hr to 360C; at 330C/hr to 40C
18mm dia.: Go at 690C/hr to 530C, 30mins.; cool at 86C/hr to 360C; at 260C/hr to 40C
20mm dia.: Go at 560C/hr to 530C, 30mins.; cool at 70C/hr to 360C; at 210C/hr to 40C
22mm dia.: Go at 460C/hr to 530C, 30mins.; cool at 57C/hr to 360C; at 175C/hr to 40C
24mm dia.: Go at 390C/hr to 530C, 30mins.; cool at 48C/hr to 360C; at 145C/hr to 40C
30mm dia.: Go at 245C/hr to 530C, 36mins.; cool at 31C/hr to 360C; at 95C/hr to 40C
38mm dia.: Go at 155C/hr to 530C, 39mins.; cool at 19C/hr to 360C; at 60C/hr to 40C
50mm dia.: Go at 90C/hr to 530C, 46mins.; cool at 12C/hr to 360C; at 36C/hr to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
Up to 10mm dia.: afap to 530C, 30 mins; cool at 280C/hr to 360C; 840C to 40C.
12mm dia.: Go at 1000C/hr to 530C, 30mins.; cool at 194C/hr to 360C; at 580C/hr to 40C
14mm dia.: Go at 1000C/hr to 530C, 30mins.; cool at 142C/hr to 360C; at 425C/hr to 40C
16mm dia.: Go at 870C/hr to 530C, 30mins.; cool at 109C/hr to 360C; at 330C/hr to 40C
18mm dia.: Go at 690C/hr to 530C, 30mins.; cool at 86C/hr to 360C; at 260C/hr to 40C
20mm dia.: Go at 560C/hr to 530C, 30mins.; cool at 70C/hr to 360C; at 210C/hr to 40C
22mm dia.: Go at 460C/hr to 530C, 30mins.; cool at 57C/hr to 360C; at 175C/hr to 40C
24mm dia.: Go at 390C/hr to 530C, 30mins.; cool at 48C/hr to 360C; at 145C/hr to 40C
30mm dia.: Go at 245C/hr to 530C, 36mins.; cool at 31C/hr to 360C; at 95C/hr to 40C
38mm dia.: Go at 155C/hr to 530C, 39mins.; cool at 19C/hr to 360C; at 60C/hr to 40C
50mm dia.: Go at 90C/hr to 530C, 46mins.; cool at 12C/hr to 360C; at 36C/hr to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
Monday 26 July 2010
Bead Annealing Schedule for Bullseye Beads
This table is based on James Kirwin’s work on bead making with variations. This is for cold beads being heated for a secure anneal.
Up to 10mm dia.: afap to 540C, soak for 30min., cool at 300C/hr to 370C; afap to 40C.
12mm dia.: 1000C/hr to 540C, soak for 30min., cool at 220C/hr to 370C; 600C/hr to 40C
14mm dia.: 1000C/hr to 540C, soak for 30min., cool at 165C/hr to 370C; 480C/hr to 40C
16mm dia.: 1000C/hr to 540C, soak for 30min., cool at 125C/hr to 370C; 375C/hr to 40C
18mm dia.: 900C/hr to 540C, soak for 30min., cool at 100C/hr to 370C; 300C/hr to 40C
20mm dia.: 600C/hr to 540C, soak for 30min., cool at 80C/hr to 370C; 240C/hr to 40C
22mm dia.: 535C/hr to 540C, soak for 30min., cool at 67C/hr to 370C; 200C/hr to 40C
24mm dia.: 450C/hr to 540C, soak for 30min., cool at 55C/hr to 370C; 165C/hr to 40C
30mm dia.: 280C/hr to 540C, soak for 36min., cool at 36C/hr to 370C; 110C/hr to 40C
38mm dia.: 180C/hr to 540C, soak for 36min., cool at 22C/hr to 370C; 66C/hr to 40C
50mm dia.: 100C/hr to 540C, soak for 46min., cool at 13C/hr to 370C; 36C/hr to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
Up to 10mm dia.: afap to 540C, soak for 30min., cool at 300C/hr to 370C; afap to 40C.
12mm dia.: 1000C/hr to 540C, soak for 30min., cool at 220C/hr to 370C; 600C/hr to 40C
14mm dia.: 1000C/hr to 540C, soak for 30min., cool at 165C/hr to 370C; 480C/hr to 40C
16mm dia.: 1000C/hr to 540C, soak for 30min., cool at 125C/hr to 370C; 375C/hr to 40C
18mm dia.: 900C/hr to 540C, soak for 30min., cool at 100C/hr to 370C; 300C/hr to 40C
20mm dia.: 600C/hr to 540C, soak for 30min., cool at 80C/hr to 370C; 240C/hr to 40C
22mm dia.: 535C/hr to 540C, soak for 30min., cool at 67C/hr to 370C; 200C/hr to 40C
24mm dia.: 450C/hr to 540C, soak for 30min., cool at 55C/hr to 370C; 165C/hr to 40C
30mm dia.: 280C/hr to 540C, soak for 36min., cool at 36C/hr to 370C; 110C/hr to 40C
38mm dia.: 180C/hr to 540C, soak for 36min., cool at 22C/hr to 370C; 66C/hr to 40C
50mm dia.: 100C/hr to 540C, soak for 46min., cool at 13C/hr to 370C; 36C/hr to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
Thursday 22 July 2010
Bead Annealing Schedule for Borosilicate Beads
This table is based on James Kirwin’s work on bead making with variations. This is for cold beads being heated for a secure anneal.
Up to 10mm dia: afap to 570C, soak 30 mins; anneal at 900C/hr to 500C; afap to 40C
12mm dia: 1000C/hr to 570C, soak 30mins; anneal at 630C/hr to 500C; afap to 40C
14mm dia: 1000C/hr to 570C, soak 30mins; anneal at 468C/hr to 500C; 1000C to 40C
16mm dia: 1000C/hr to 570C, soak 30mins; anneal at 355C/hr to 500C; 1000C to 40C
18mm dia: 1000C/hr to 570C, soak 30mins; anneal at 280C/hr to 500C; 840C to 40C
20mm dia: 1000C/hr to 570C, soak 30mins; anneal at226C/hr to 500C; 675C to 40C
22mm dia: 1000C/hr to 570C, soak 30mins; anneal at 187C/hr to 500C; 560C to 40C
24mm dia: 1000C/hr to 570C, soak 30mins; anneal at 157C/hr to 500C; 470C to 40C
30mm dia: 800C/hr to 570C, soak 36mins; anneal at 100C/hr to 500C; 300C to 40C
38mm dia: 500C/hr to 570C, soak 39mins; anneal at 60C/hr to 500C; 180C to 40C
50mm dia: 285C/hr to 570C, soak 46mins; anneal at 36C/hr to 500C; 100C to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
Up to 10mm dia: afap to 570C, soak 30 mins; anneal at 900C/hr to 500C; afap to 40C
12mm dia: 1000C/hr to 570C, soak 30mins; anneal at 630C/hr to 500C; afap to 40C
14mm dia: 1000C/hr to 570C, soak 30mins; anneal at 468C/hr to 500C; 1000C to 40C
16mm dia: 1000C/hr to 570C, soak 30mins; anneal at 355C/hr to 500C; 1000C to 40C
18mm dia: 1000C/hr to 570C, soak 30mins; anneal at 280C/hr to 500C; 840C to 40C
20mm dia: 1000C/hr to 570C, soak 30mins; anneal at226C/hr to 500C; 675C to 40C
22mm dia: 1000C/hr to 570C, soak 30mins; anneal at 187C/hr to 500C; 560C to 40C
24mm dia: 1000C/hr to 570C, soak 30mins; anneal at 157C/hr to 500C; 470C to 40C
30mm dia: 800C/hr to 570C, soak 36mins; anneal at 100C/hr to 500C; 300C to 40C
38mm dia: 500C/hr to 570C, soak 39mins; anneal at 60C/hr to 500C; 180C to 40C
50mm dia: 285C/hr to 570C, soak 46mins; anneal at 36C/hr to 500C; 100C to 40C
Remember this table is for spheres. For cylinders choose the diameter that is 1.5 times the diameter of your cylinder, and for flat shapes choose the diameter that is 3 times the thickness of your piece.
For other information on annealing of beads go here
Sunday 18 July 2010
Bead Annealing
There are two approaches to annealing beads.
One is to keep them warm as you make them and when the session is finished, anneal all the beads sitting in the kiln. Assuming you are using soda lime glasses rather than borosilicate, you need to have the kiln idling at around 500C. When you have evened the heat throughout the bead, you place it in the kiln. Gloves and other heat protection attire will be needed when you open the door/lid to put the bead on the mandrel into it.
When you have finished the bead making session, you then take the temperature up to about 520C – 540C and soak there for about half an hour – both depend on the type of glass and the thickness and shape. The object is to take the glass up to a temperature where the annealing process can work, but without being so high in temperature that the bead takes up marks from the kiln shelf. More information on the soak and annealing of various shapes, sizes and types are given in later tips.
The second method applies if you have cooled the beads in vermiculite, blanket or other means to cool them slowly and you now have a group of cold beads that you wish to ensure are correctly annealed. You need to start the kiln from cold. Place the beads in the kiln and begin the firing. You need to take the beads up slowly – not more than 300C/hr - to between 520C and 540C, and soak there for about an hour. More information is given in further tips.
In both the cases described you now have the beads with the temperature equalised throughout the bead, and the annealing can begin. The annealing is the controlled cooling below the annealing soak. It is generally safe to take the temperature down at about 80C/hr to 360C. After this point you can speed up the cool down to something like 200C/hr, or if you kiln cools slowly enough, just turn it off and wait for the temperature to come down toward room temperature. This again depends on the type of glass, its size and shape.
Variations according to glass type used, sizes and shapes follow in further tips.
Annealing of Borosilicate Beads
Annealing of Bullseye Beads
Annealing Effetre Beads
Annealing Spectrum 96 Beads
Effect of Shape
Effect of Size
Effect of Variations in Sizes
One is to keep them warm as you make them and when the session is finished, anneal all the beads sitting in the kiln. Assuming you are using soda lime glasses rather than borosilicate, you need to have the kiln idling at around 500C. When you have evened the heat throughout the bead, you place it in the kiln. Gloves and other heat protection attire will be needed when you open the door/lid to put the bead on the mandrel into it.
When you have finished the bead making session, you then take the temperature up to about 520C – 540C and soak there for about half an hour – both depend on the type of glass and the thickness and shape. The object is to take the glass up to a temperature where the annealing process can work, but without being so high in temperature that the bead takes up marks from the kiln shelf. More information on the soak and annealing of various shapes, sizes and types are given in later tips.
The second method applies if you have cooled the beads in vermiculite, blanket or other means to cool them slowly and you now have a group of cold beads that you wish to ensure are correctly annealed. You need to start the kiln from cold. Place the beads in the kiln and begin the firing. You need to take the beads up slowly – not more than 300C/hr - to between 520C and 540C, and soak there for about an hour. More information is given in further tips.
In both the cases described you now have the beads with the temperature equalised throughout the bead, and the annealing can begin. The annealing is the controlled cooling below the annealing soak. It is generally safe to take the temperature down at about 80C/hr to 360C. After this point you can speed up the cool down to something like 200C/hr, or if you kiln cools slowly enough, just turn it off and wait for the temperature to come down toward room temperature. This again depends on the type of glass, its size and shape.
Variations according to glass type used, sizes and shapes follow in further tips.
Annealing of Borosilicate Beads
Annealing of Bullseye Beads
Annealing Effetre Beads
Annealing Spectrum 96 Beads
Effect of Shape
Effect of Size
Effect of Variations in Sizes
Wednesday 14 July 2010
Removing Beads Stuck to the Mandrel
You may need to hold the mandrel in pliers or in vice grips while holding the bead with a scrubbing pad or jar opening rubber pad.
If this does not work, try soaking the bead and mandrel in water for a few hours. This often is enough to release the bead.
A little more drastic method is to then place the bead and mandrel in the freezer. After being frozen, the bead will most often come off as the water in the bead release thaws.
A final attempt can be made with a pop rivet gun. Insert the mandrel and operate the levers, and it will push the bead off the mandrel.
If all other things fail and you really want your mandrel back, you can warm the bead in the flame and dump it in water. It will break apart with the shock from the water. You can then clean up the mandrel for future use.
If this does not work, try soaking the bead and mandrel in water for a few hours. This often is enough to release the bead.
A little more drastic method is to then place the bead and mandrel in the freezer. After being frozen, the bead will most often come off as the water in the bead release thaws.
A final attempt can be made with a pop rivet gun. Insert the mandrel and operate the levers, and it will push the bead off the mandrel.
If all other things fail and you really want your mandrel back, you can warm the bead in the flame and dump it in water. It will break apart with the shock from the water. You can then clean up the mandrel for future use.
Saturday 10 July 2010
Bubble Squeeze
One of the most effective ways of reducing bubbles is to adjust the schedule to allow the top glass to slump down onto the bottom sheet before the glass is soft enough to stick at the edges and trap air. This is commonly referred to as a “bubble squeeze”.
A common method is to insert a soak at the slumping temperature of the glass. You will have found that the glass will take up the form of a simple slump at a lower temperature than more angular forms. Use this lower temperature for 30mins to an hour. You may want to extend that soak time depending on the thickness and complexity of the layup.
Another method is to start the squeeze about 55C above the annealing soak temperature and increase the temperature slowly (27-55C per hour) until you are at the slump temperature.
You can also combine the two above methods by soaking at the slump temperature for 30 minutes to an hour – or longer for thick and complex pieces – after the slow rise.
If your kiln is a side fired one, you need to be especially careful, as the edges of the glass become hotter than the centre. Two options are available - fire more slowly, or place baffles around the outside of the piece to prevent direct radiation of the heat onto the edge of the glass.
A common method is to insert a soak at the slumping temperature of the glass. You will have found that the glass will take up the form of a simple slump at a lower temperature than more angular forms. Use this lower temperature for 30mins to an hour. You may want to extend that soak time depending on the thickness and complexity of the layup.
Another method is to start the squeeze about 55C above the annealing soak temperature and increase the temperature slowly (27-55C per hour) until you are at the slump temperature.
You can also combine the two above methods by soaking at the slump temperature for 30 minutes to an hour – or longer for thick and complex pieces – after the slow rise.
If your kiln is a side fired one, you need to be especially careful, as the edges of the glass become hotter than the centre. Two options are available - fire more slowly, or place baffles around the outside of the piece to prevent direct radiation of the heat onto the edge of the glass.
Tuesday 6 July 2010
Uneven Heating Effects
If the glass is heated unevenly, it can lead to bubbles between the shelf and the glass, causing large bubbles with thin structures, if not actually burst. This can happen especially with side or side and top firing kilns. The solution to this is to [baffle] the edges of the glass from the direct heat of the elements.
Friday 2 July 2010
Rapid Firing Effects
Bubbles between the glass and the shelf can be caused by firing too quickly. Fast firings can cause the glass at the edge to soften early and trap air underneath the glass. At fusing temperatures the air blows a bubble through the glass. Solutions for this are described in
[bubbles between the glass and the shelf]
[bubbles between the glass and the shelf]
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