Showing posts with label Designing. Show all posts
Showing posts with label Designing. Show all posts

Wednesday 22 September 2021

Firing cremains to avoid bubbles

Firing with cremation remains is very similar to firing with any organic material encapsulated into glass.

Design
There are several possible design approaches.

Drilling holes is one method to avoid bubbles.  You can drill the base, put the remains on top and then cap.  Place the whole assembly on 1mm fibre paper to allow the air to migrate out through the hole and fibre paper under the glass.

Alternatively, you fire upside down and then fire polish the top.  Place the eventual top down onto the kiln washed shelf or Thinfire. Place the remains on the glass and cap with the glass that has the hole drilled.  Fire, then clean, turn over and fire polish the final top surface.

Design the piece and placing so there is a gap at the edge. 
This gives a route for air to escape.  If there is any gap left after fusing, it can be filled with a bit of super glue or other clear glue. 

Another method is to place pieces of frit or stringer at the very edge of the base glass to allow air out from under the centre of the piece.

If you do not need to concentrate the cremains in one area, you can disperse the material evenly across the piece to reduce the possibility of large bubbles.  The air and gasses can migrate to the edge through the particles, just as happens with powder sprinkled between layers of glass.

You can combine some of these methods as they are not mutually exclusive.


Firing
Fusing these pieces is, in principle, the same as encapsulating any organic material within the glass.  Slow advances are required with a 3 to 4-hour soak at around 600°C to burn out any residual organic material just as you might for thick vegetable matter.  You can add another bubble squeeze soak of an hour or so at around 650°C to gradually push any remaining air out from between the particles.  Then advance to the fusing temperature and anneal as usual.


Wednesday 27 March 2019

Observation

The importance of Observation (and recording)


Observing what you, or the kiln, is doing whether you are using a cartoon, or a schedule obtained from elsewhere – including the kiln manufacturer – means that you will learn much more quickly as you progress.  You will be able to alter things as you go.  This applies to all stages of the piece from design to removing the piece from the kiln.

The Design

Once you have made your design – whether as a drawing or a mock-up – look at it.  Really look at it.  Look at it from a distance, climb a ladder if you can’t pin it on a wall and look down on it.  Look at it from the sides so you have an oblique angle view.  Turn it upside down to confuse your expectations and so see what is really there.  Look at it, using a mirror to see if it still looks good. Make the alterations you need as you go along to get the look you want and then repeat the process until you are happy.

Assembly

Observe how you have put the piece together.  Do the pieces fit?
Is everything in the right place? Are the colours right? Does it match your vision – symmetrical or asymmetrical?   Do these things as you progress, so you become aware of the process and its rhythm.

Firing

Once you have determined your schedule, you cannot just leave the piece. If you are new to fusing, you need to observe the stages of firings to begin to understand what is happening to the glass at various temperatures and rates of advance. You would not put a cake into the oven and leave it without checking on it from time to time. Why would you fail to observe a much more expensive process?

Even when you are experienced  - observation of new layups, new processes and anything you haven’t done several times before - you need to know how things are progressing during the firing.

Observing a firing is relatively simple.  You need to check on two things:

·   Check for a too rapid rate of advance.  Peek into the kiln at around 540C to see if the piece is still whole.  If not, you can abort the firing and progress to fixing or move on to another project.

·   Check to see when the desired shape has been achieved.  Peeking to see if the slump is complete or needs more time is important to getting the shape right.  Peek to determine if the tack fuse has been achieved.  When it has, advance to the next segment to avoid over firing.  If it hasn’t, add time to the schedule to get it right.

Recording

It is not enough to simply observe.  You need to record what you intended and the results you achieved.  That includes what you did to get things right as well as wrong.  What did you do to correct elements?  These are all things that you will need to refer to in the future.

The key to rapid learning is observation and recording what you see.

Wednesday 13 March 2019

Textured Side



There is a little concern about whether the textured side of the glass pieces in leaded and copper foiled glass should be towards the inside or outside.

The traditional advice is to have the textured side toward the inside.  This is based on the piece being used as a window. It is easier to keep the weather side clean if the smooth side is on the outside. The same thinking leads to the recommendation to allow the cemented panel to rest with the smooth (outside) down.  This minimises the thickness of the putty and so allows less water to collect on the outside horizontal leads.

If the window is not primary glazing, it does not matter which side, nor how consistent you are in placing the glass.  It becomes a matter of aesthetics – which ever way you prefer is fine if it gives you the effect you want.

There is a small visual effect if you are using transparent glass.  There is slightly more dispersion of light if the textured side is outwards. 

Placing the textured side inwards can be useful if you wish to indicate a rough surface contrasting with a smoother one.

These considerations show that the placing of the textured side is largely determined by the function of the panel and the aesthetics applied.

Wednesday 19 April 2017

Light and Dark in Designs

Chiaroscuro – This word borrowed from Italian ("light and shade" or "dark") refers to the modelling of volume by boldly contrasting light and shade. 

Glass artists need to be very cognisant of light and dark, both in terms of colour selection and in terms of density. A very thick dense glass of a dark shade of any colour will create a much more intense darkness than glass that is thinner and less dense.


In terms of colour, lighter hues go where the sun shines or where the eye is to be drawn. Pastel shades indicate brightness and light. Within some opalescent and art glasses it is possible to find a shade of colour graduating to white or light yellow. 


Shading can be achieved by using the white areas to indicate where light is falling. A denser dark glass can be used to indicate where light does not fall, or where very little light can filter through. It can also play the part of negative space.



Sometimes, it is useful to use a monochrome scheme to assist in determining where the light and dark should be, as in this pear:


The contrast between light and dark can be used in several ways. Darkness can indicate depth of field or distance when used in a general landscape. Or, it can be used to bring a foreground out, making other elements more vivid.


The key thing to remember in using stained glass is to not be afraid of dark glasses. They can very useful, even if of very odd hues of colour.

Saturday 11 March 2017

Drawing an Oval

Need to draw an oval for a panel? Here's how:
  • Set out the long axis horizontally.
  • Set out the short axis at the half way point of the long axis at right angles to the horizontal.
  • Measure half the short axis on each side of the long, horizontal axis.
  • Calculate half the measurement of the longest line. In this example the long line is 340mm and the short axis is 200mm long.  
  • Half the long axis is 170mm.
  • Use that as a diagonal measurement from the end of the vertical axis. 

  • Measuring from the end of the shortest line, mark off this amount on the longest line, right and left. You can use a ruler or compass set to the correct length, both will work.
  • Insert a pin at both these points.

  • Place a piece of thread, string - or in this case a quick release tie - round one pin. Tie a knot in the thread at the far end of the longest line.
  • Put a pencil inside the loop. Pull the thread taut and begin to draw the oval.  Keep the tension even throughout the drawing to avoid a lopsided oval.

For a leaded panel, the space occupied by the lead came will need to be accounted for in the measuring of the dimensions.

This is a simple method that does not require much in the way of tools, but its accuracy is a result of the degree of attention to details.

Wednesday 16 November 2016

Thinking About Design

To think about design, you need a vocabulary to describe the object. This needs to be combined with a structure of principles. What follows is an outline to structure your thinking about design.  This is based on the writing of Burton Wasserman in Spark the Creative Flame, Making the Journey from Craft to Art, by Paul J Stankard, 2013.


First there is the vocabulary to structure the conversation about design. The elements of this are “… point, line, plane, texture, colour, pattern, density, interval, … space, … light, mass, and volume”

There are then principles of good design.  They relate to:
Unity – all the elements form a whole
Balance – note, not only symmetry
Rhythm – this can be repetition with or without variation
Emphasis – or contrast between a main element and the rest
Harmony – all the elements work together


These five principles of design together with the vocabulary of elements form the language of design and assist your critical thinking about expressing your design and realising it in the best way you can.  This thinking can be applied usefully to the critical appreciation of others’ works.

Wednesday 14 September 2016

Line Widths for Cartoons


The lines for copper foil and lead cartoons need to be of different sizes.  Only a small width is required between glass pieces in copper foil.  This allowance is for the two thicknesses of foil and a space for the solder to run through from front side to the back side.  In leaded glass a wider line is needed to allow for the width of the heart of the came.

On cartoons for different methods, draw the lines in the appropriate width.  For copper foil this width is ca. 0.8mm.  This can be accomplished with a ball point pen or fine felt tip. 

For leaded glass panels, a thicker line of ca. 1.6mm is required. A bullet tipped felt pen is usually appropriate, if it is not worn down at all.

A cartoon for fused glass should use the finest line possible, as the glass pieces will be in direct contact (ideally) with each other.  As in copper foil, a ball point or fine felt tipped pen will be appropriate.


Wednesday 29 April 2015

Large Bubbles

cambridgecreativenetwork.co.uk
Some times you want large bubbles, but when you don't, you need to know about the causes of, and ways to prevent, bubbles.

Causes and prevention of most large bubbles relate to volume control, layup, rate of advance and top temperature.

Volume control. We all know that glass tends toward being 6-7mm thick at full fuse temperatures. Any less volume and the glass thickens at the edges, so trapping air under the glass which will push up and through given enough time and temperature.

Layup. The lack of volume control is compounded by layups which do not allow the air to escape from under the edges of the piece.

Rate of advance. These two problems are compounded by asap, or even just rapid, increases in temperature. The glass softens quickly and the air finds it easier to push the glass up than to escape from under the edges. Slowing down is part of the answer.

Top temperature. A high top temperature softens the glass to the extent that any lack in volume control, layups that have hollows or traps for air, and rapid increases in temperature all allow the expanding air (and there will always be some) underneath the glass to push up and often through the glass.

These factors reinforce the Low and Slow mantra.

Other factors can promote bubbles, although the ones above are the most common. Debris between the glass and the shelf, or between glass layers can cause bubbles, given the right conditions. Small shallow indentations in the shelf can be the source of bubbles from underneath the glass. This can be identified by observing where the bubbles occur in relation to the shelf.

There are some things that can be done to reduce the likelihood of bubbles:








Wednesday 27 November 2013

Disguising Joints in Fusing


One advantage of fusing over leading or copper foiling is that shapes impossible to cut as a single piece can be made from multiple pieces. However these joints often show up in the finished work.

You are always more likely to have the joints show when the cut coloured glass is on the bottom. The infra-red heat of the kiln elements goes through the clear glass to the coloured below, allowing it to soften first. As the glass underneath softens and pulls in, it allows the top glass to sink into the space. Upon cooling the seam is kept open even sometimes showing a clear line at the joints.

Putting the clear as the base and the jointed pieces on the top has a better chance of having the joints fully fuse together. There is no glass above to spread the pieces apart.

When you need the joints to be concealed, you can put a line of powder the same colour of glass over the joint. This line should be slightly rounded above the surface along the joint to account for the reduction in volume as it fuses. When it is two colours meeting, using powder of the same colour as the darker glass is most successful.

Fusing to a contour fuse for 10 minutes is normally hot enough, but taking the piece to a flat fuse – again for 10 mins - will certainly be enough to fully melt the powder into the joint.

Thursday 25 April 2013

Radiating Lines


In designs for leaded and copper foiled glass it is important to avoid lines radiating from a single point. Some of these reasons are:



It is important to reduce the number of lines that meet in any design to avoid a big bright solder place in a panel.


Example of pattern with radiating lines

It makes for large solder blobs, especially on leaded glass panels, and therefore provides a focus where one may not be wanted or required.

The difference between the harder solder and softer lead came leads - over time - to cracks in the lead at the edge of the thick solder blob.

In leaded and copper foiled glass it is a point of weakness, as there are likely to be multiple thin or tapering pieces of glass that are liable to fracture early in the life of the panel.

Methods of Avoiding

This umbrella image avoids long narrow pieces by having the ribs and supports crossing to make short narrow pieces

Narrow tapering pieces can be compensated for by making the narrow parts shorter than the wider parts of the taper – although this does add to the density of lead and solder around the termination point. There is a difficulty in adapting single radiating points in a drawing to the practicalities of the medium of glass. Examination of older panels (in either technique) will show some of the problems of thin tapering pieces. It is obvious in older windows, especially in the Victorian Era, when tapered pieces where in their glory. Almost always, the tips are broken. It is the nature of glass, and goes back to knowing how the medium will react to the conditions you create.

The central circle avoids joining all the radiating lines at one point

Good design will avoid multiple radiating pieces from a single point of origin.

It is not possible to make a neat termination by joining half a dozen tapers at one point. The finished piece will not look like it did when it was drawn out with a pencil. You can pencil in a termination with six points, ending at one point and it may look good, but when you draw the design with the width of the led or foil will show the clumsy nature of the design with a large termination point.

As you can see, the answer starts with the design, before you cut and foil, or fit the came to the glass. Art is not about the physical placement of what you see in your mind, as much as it is about the "illusion" you are creating that you want others to see. That starts with the design, and avoiding something that you know is going to give you a problem.

It is not possible to make a neat termination by joining half a dozen tapers at one point. The finished piece will not look like it did when it was drawn out with a pencil. 


Example of a design that will present difficulties at the centre

You can pencil in a termination with six points, ending at one point and it may look good, but when you draw the design with the width of the led or foil will show the clumsy nature of the design with a large termination point. As you can see, the answer starts with the design, before you cut and foil, or fit the came to the glass. Art is not about the physical placement of what you see in your mind, as much as it is about the "illusion" you are creating that you want others to see. That starts with the design, and avoiding something that you know is going to give you a problem.

Thursday 10 January 2013

Avoiding Large Bubbles



I tried small projects and they turned out fine. I have a 12" square with an emblem in the centre and a border set in slightly from the sides. Most of the glass is only the one layer. Both firings produced huge bubbles in the areas where the glass was only one thickness.”

Scale does matter. What can be done at a small scale does not always directly transfer to a larger scale.

The first problem this project created was using only one layer as the base. Glass has a surface tension which means that it tries to become 6-7 mm thick. One layer is only half that. As it thickens at the edges, it traps the air under the other parts of the glass, and as the glass continues to soften the expanding air bubbles come up through the thin parts of the glass.

Using two layers of glass with the design on top will ease the problem.


The design is the second problem. The weight of the border makes it even more difficult for the air to get out from under the glass.

Although having two layers of glass will reduce the problem, think about ways to make the border incorporated with the second layer of glass, so the weight of the glass at the perimeter is not greater than the interior.


The third problem is that there is not a bubble squeeze in the schedule (elsewhere in the query). The soak of 10 minutes at 538C is not necessary. You do need a soak at a point between 650C and 677C - this is the bubble squeeze temperature range. It is also the slump temperature, so you can determine what the bubble squeeze should be for your glass by what the slump temperature is.

The bubble squeeze can be accomplished by a half hour soak at the slump temperature, or by a slow rise from 50C below the slump temperature – taking an hour or so, depending on the size of the piece.


A fourth problem is the separator is batt (kiln) wash, the edges of the glass conform to the batt wash, resisting the movement of air from under the glass.

You may need to change to fibre paper for single layer pieces, as that allows more air out. Thinfire may be enough, but you can put it over 0.5 mm fibre paper. For a smoother finish, sprinkle powdered batt wash over the fibre paper and smooth it with a plasterer's float or a piece of window glass if you don't want to use Thinfire.


Lastly, don't use the pre-programmed schedules in your kiln's controller.

Look at the glass manufacturer's website. Bullseye, Spectrum and Uroboros give basic firing schedules that work with minimal adjustment. I don't understand why kin manufacturers don't simply refer to the sites to give their customers good advice, instead of the pre-programmed stuff.


Monday 10 December 2012

Diamond Quarries


Diamond quarry glazing appears to be simple. But because if its simplicity it must be both accurate and aesthetically pleasing. Diamond quarried windows look best if the individual pieces are taller than they are wide. The window also looks better if the lines forming the diamonds end in the corners of the window as it gives a pleasing wholeness.

Simple sketches to show the relative clutter of a 6x6 and a 4x4 pattern

You can try making a sketch and trying various options of numbers and angles. By this simple exercise, you can determine the amount of clutter (how many lines vs. how much glass shows) produced by various combinations. It is important that the proportions of your sketch should be the same as the that of the window for which you are designing. This sketching process lets you try out various numbers of quarries along the bottom and sides quickly as the lines do not have to be accurate. Once you have decided on a size that looks good on the sketch you can count up the number of divisions on the horizontal and vertical lines. This can then be translated into approximate sizes on the full sized cartoon.


Begin with the cut line cartoon. This seems obvious, but until you have measured the window and given the glazing and border leads allowance you are unable to design a damond quarry glazed window that will have its lines meeting the corners in the finished window.


Drawing the diagonals


Begin the designing process by drawing two diagonal lines from the corners of the panel to ensure the lines will finish in the corners. This will also determine the centre of the panel and show you the slope of the diagonals. If you have not already determined the size of the diamond quarries, you can try out different sizes of diamonds by drawing parallel lines to the diagonals. 

Centre point determined, trial sizes of quarry, and the sides divided

When you have a size you like, you can determine the number of diamonds horizontally and vertically across the panel. You need to measure the width and height – point to point – of the test diamond and divide the lengths of sides to determine the number of quarries up and across the window. 

In this example of a small window (380 mm x 280 mm), the quarry is about 50mm wide and 65 mm high.  The exact sizes are not too important.  Divide the length of the base and side lines to determine the number of divisions.  In this example it is five on the base and six on the side. To get the exact dimensions for the quarries, you can use the no-calculation method of dividing a line. [link]

The divisions are extended to the opposite vertical or horizontal line to provide points from which to draw the diagonals.

Lef to right diagonal lines drawn
In this example feint lines were drawn up and down across the panel.  This provides a check that the diagonals remain accurate.

Remaining diagonals drawn  and confirmed by horizontal and vertical check lines


Sometimes, however, the corner to corner diagonals are too steep or too shallow to make pleasing diamonds. Diamond quarries generally have slopes that fall in the range of 50 – 60 degrees (45 degrees gives square quarries and anything over 60 degrees gives such a narrow quarry as to be unplesant). In these cases you need to determine the approximate angle for the diamond shape before proceeding from the centre point. 

Centre found and test diagonal drawn
In this landscape format example the diamond is horizontal, but otherwise a suitable size, so the dimensions were taken of it to determine the number of quarries on each side.  In this case it was seven along the bottom and four along the side.

Normally a 55 degree angle is a suitable middle range slope for diamonds, so you can start with that to determine what number of pieces vertically and horizontally are appropriate.  

After marking off the equal number of spaces, you can determine which points will give you appropriately angled diagonals. 

Number of quarries determined and first diagonal drawn
It is important to count the same number of marks along on the base line as there are marks on the side.  You will see in the above picture - if you look closely - the effects of narrowing diamonds if you do not.

The second set of diagonals being added
After setting the diagonals on the first side and part of the base, continue with the parallel lines to the end.

Completed set of diagonals for a landscape window

This photo shows the completion of the diagonals.  It also shows the need for concentration.  I was interrupted and when I came back I drew a line from centre top to the next to last mark on the cartoon.  However, as you can see from the erasing, it should have been the corner mark that I drew to.  I point this out to emphasise how important it is to concentrate while doing this apparently simple task of joining the marks.

Wednesday 5 December 2012

Dividing a Line

Dividing a Line into Equal Parts

There is a no-calculations method of dividing a line into equal parts. This describes how to divide a line into any number of equal parts without calculating and measuring the divisions.

The steps are:
Determine the number of divisions required across the base or perimeter line. Then draw a long line at a shallow angle to the line to be divided.

Angled line and dividers

Take a pair of dividers and open them to the approximate width of the individual division or piece.  In this example it was decided to have five divisions of about 50 mm.  The dividers are opened to 50 mm and marked off on the angled line from the corner the required number of times - in this case five.  

Then make a line from the last mark to the angled line to the end of the cartoon line with a right angle drawing square. 

Setting the angle

Place a long straight edge on the bottom of the drawing square and then mark the remaining divisions by maintaining the angle of the long straight edge while moving the drawing square from one mark to another. 

Moving the drawing square along the line and marking the base line


This process allows you to make equal divisions of a line without worrying about fractions of a centimetre or of an inch. It is simple and just as accurate as your skill in holding the straight edge steady while you run the drawing square along the edge and mark the base or vertical line.  In general it is more accurate than any calculations and measurements on the base or vertical lines.

Sunday 25 November 2012

Quarry Glazing


For some reason that I have never learned, the regularly shaped pieces of glass that are leaded into a window are called quarries.  The derivation of the word relating to excavation comes from its middle English variant of medieval Latin quareria, from Old French quarriere, based on Latin quadrum 'a square'.   How it came to be applied to pieces of glass is unknown apparently.  However, in stained glass, "quarries" can relate to rectangles, diamonds, circles, etc., not only squares

These kinds of glazing are weak as there are long straight lines created with these designs. The best way of counteracting this weakness is to “weave” the lead joints within the panel combined with more frequent than usual glazing bars.

It may be wise to use a glazing bar at every second set of joints rather than merely consider the distance between bars.

Monday 10 September 2012

Overlapping Joints

Overlapping Joints in paneled windows

In many installations of tall windows, such as churches or tall sidelights, there is a requirement for handling and transport that the window be built in panels, each of which sit on top of the other. There are some considerations about the design and installation of such windows.

The design has to allow for the additional thickness of at least two hearts at the joins of the panels.

The leaves of the upper leads should always overlap the lower leads to be able to shed water from the rain so it does not migrate inside.

There should be wide heart “H” leads on the bottom of each panel. These should be 12mm or 16mm wide heart flat leads on all except the bottom panel where the normal 5mm heart can be used.  The wide heart lead allows easy placing of the upper panel onto the lower one.  It is possible to open the leads of a standard heart lead, but it is much easier to use a wide heart lead.

The top leads on each panel should be flat leads of 10mm or “U” lead. This is largely preference. If you use “H” leads at the top, you should fold the leaves over, or cut them off, depending on the allowance in the design.

The openings should have glazing or saddle bars placed at the levels where the panels join. These need to be tied to the panels with tie wires soldered onto the panels. The ties on the panels should be soldered so that the ties on the bottom of the top panel point downwards, and the ties on the top of the bottom panels point upwards.  It is important that the soldering of the tie wire on the bottom panel is very flat and low enough to avoid interfering with the flange of the upper panel and to allow the easy setting of the top panel over the joint. It is also worthwhile to put a loop in the soldered end of the tie wires so they do not pull out of the solder joint.

Once you are certain of a good fit, set the upper panel down onto the lower one.  Dress down the opened flanges of the upper panel over the lower one.  Then draw the wires from the upper panel down behind the saddle bar, the lower wires up behind the saddle bar, fold over them over the saddle bar, twist firmly.  Cut the ends to uniform lengths and fold back the twist up and over the bar.  This secures the panels, draws the two panels together and provides lateral support to the window.

It is not necessary to putty the joint of the panels, as the flange of the upper lead is sufficient with a little dressing of the flanges flat to the lower panel to avoid any ingress of water.

Thursday 30 August 2012

Radiating Lines

In leaded glass designs it is important to avoid lines radiating from a single point.

Good design will avoid multiple radiating pieces from a single point of origin.

Among the reasons for avoiding radiating lines are:
  • It is important to reduce the number of lines that meet in any design to avoid the big bright solder place in a panel.
  • It makes for large solder blobs, especially on leaded glass panels, and therefore provides a focus where one may not be wanted or required.
  • It also is a point of weakness as the multiple thin or tapering pieces of glass are liable to fracture. 
  • Also the difference between the harder solder and softer lead came leads - over time - to cracks in the lead at the edge of the thick solder blob.

There is a difficulty in adapting single radiating points in a drawing to the practicalities of the medium of glass. Examination of older panels (in either copper foil or leaded technique) will show up some of the problems of thin tapering pieces, especially in the Victorian era where tapered pieces where in their glory. Almost always, there will be broken tips. They seemed to compensate for tip stress by making the pieces with narrow tapers smaller than some of the other wider pieces. Even then, there are a lot of broken ones seen. It is the nature of glass, and goes back to knowing how the glass will react to the conditions you create.


Methods of avoiding tapering pieces lie in the design.

You can't use long tapered pieces in larger panels, without modification for the structural reasons outlined above.

Also you can't make a neat termination by joining half a dozen tapers at one point. Your piece will not look exactly what it looks like when you drew it out with a pencil. You can pencil in a termination with six points, ending at one point and it may look good, but try drawing it in with a felt tip pen almost 6mm wide, which shows for what the solder has to  cover, and see what that point looks like then. For copper foil a 2-3mm wide line will demonstrate what will be seen after soldering. You may not be pleased with the large blob at the termination.

No one can teach one easy fix for everything you will encounter, so the answer starts with the design, before you cut and foil, or fit the came to the glass. Art is not about the physical placement of what you see in your mind, as much as it is about the "illusion" you are creating that you want others to see. That starts with the design, and avoiding incorporating something that you know is going to give you a problem.