Fixing Paint for Transport

The very cheapest hair spray works well with glass paint, if you need to transfer your painted glass to another place for firing. Complete the painting and then spray with cheap hair spray as you would to fix a charcoal drawing. This will hold the paint firmly during transport and does not affect the paint during firing.

Tracing on Opalescent Glass

Opalescent and dense glass presents problems as the usual method of tracing the image through the glass is not possible. If you first spray the glass with a cheap hair spray, this gives a “toothed” surface to the glass. Then using carbon paper an image can be transferred. However, the carbon paper leaves a greasy residue, so water based paint will not take, but an oil medium will.

Matting

Oil, and Water and Gum as Media for Matting by Dick Millard [edited from a discussion]

Oil has been used, I believe, since the 16th Century, and certainly up through the 1970's to today. It is used wherever it is determined it should be used, and one is sufficiently informed and facile to use it in a manner of delivering its full and lovely potential.

First of all, oil is not characteristically employed as a matt, out of which, by the negative process, one "takes out lights". In overwhelming instances, with which I am acquainted, it is used as a shading material applied over a pre applied and "worked" under matt of water and gum base.

This provides the required "tooth" to provide both a degree of adherence and ease of application.

So, I would suggest an oil matting, or a shading application over a smooth glass surface, would be generally problematical!

A group of blending brushes

Add a bit more gum to your water under matt which will reduce the necessity to fire that matt, which changes the character of the desired "tooth". The purpose of the "tooth" to receive the oil matt is also to provide "porosity" as an "absorbant", which additionally holds the oil mixed paint to the matt. Otherwise, the oil remains too liquid and does not float in a controlled fashion. It will require a much dryer application of kerosene, or increased absorption by additional blending.

I had a large landscape piece, hills in the back ground, that I matted and applied an alcohol mat too, but I was lifting the water mat trying to cover it with alcohol, so I added more gum to my mat and that did the trick. I also used a very soft Chinese brush. I have found that firing the mat first and looses tooth.

A group of stippling brushes

I have noticed over time that some people seem to have the impression that the less gum used, the better. I advise not to use an excessive amount of gum arabic, as a soft matt, with a soft touch produces a soft look. This is interpreted to mean 'less is better'. That is true, but only up to a point. If too little gum is used, or none, it will come off as if it were flour or mud diluted with water and applied. Too little gum severely jeopardizes any opportunity to produce soft gradation from the highlight to the untouched matt.

Tracing with a Pen

Example of a pen nib

Using paint mixed with essential oil or turpentine and with a fine mapping pen for small lettering works well, as the oil flows better than water. Although with practice, a water based paint can be used with a pen, but it is a little tedious as the pen has to be loaded frequently with a tracing brush and constantly cleaned as the water dries quickly.

Examples of nibs and holders

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.

Aperture Drops Blank Sizes

As the glass drops through the aperture, it stretches, but the whole substance of the piece is drawn toward the hole. If there is not enough spare glass around the hole, the whole piece will be drawn through the aperture.

There is a minimum size of the glass in relation to the size of the drop out hole. Up to some maximum size, the greater the diameter of the hole the 
greater the amount of spare glass there needs to be.

Also relevant is the depth of the drop. A shallow drop needs only a few centimetres larger than the hole. While a deeper drop needs a greater amount of glass surrounding the hole.

I have found that for a 300mm diameter hole, with a 150mm drop the glass needs to be 35mm larger all around. Thus an aperture of 300mm needs to be at least of 370mm diameter for this 150mm drop. I have done drops with 550mm diameters with only a 650mm diameter blank. This indicates to me that there is an amount of spare glass that will be sufficient even for larger diameter drops, but I have not found it yet.

One element that can reduce the size of the blank is to make an inclined collar around the aperture of the drop mould.  

This idea is based on the observation that as the glass begins to fall through the aperture, the outer edges of the glass rise from the mould surface so the glass is resting only on the inner edge of the drop out mould. 

This inclined drop out mould will be like a shallow bowl rim, but without a bottom. The glass blank then rests with only its outer edge on the collar.  When the temperature increases to the point that the glass begins to slump, the glass will conform to the slope and so create enough friction to restrict the glass from falling through the aperture, although it is with a smaller than normal rim.  The actual size of the rim for each size and depth will need to be determined by experience. 

More information can be found here

Temporarily Securing Panels

When installing panels into an window opening or frame, you often need to secure it while you finish puttying or use other forms of weather proofing.

If you use sprigs (headless nails) or even carpet tacks, use them where there are leads meeting the perimeter. There us less chance of a stray hammer strike hitting the glass. It is more likely to strike the lead and so cushion the impact to the panel. I also use a straight putty knife behind the nail or sprig to avoid even the chance of a strike directly on the lead.

These precautions, with suitable modifications, are applicable to copper foiled and fused panels.

Initial Heat Up Rates

Example of a graph of a heat up for industrial purposes

There is quite a lot of information on the annealing cool rates, but not so much on the initial heat up rates. This is probably because the cooling rates are more critical than the heat up. But everyone knows that you can heat the glass up too quickly for its thickness.

My experience leads me to suggest some heat up rates to 50C above the annealing temperature for circular and nearly square full fused pieces. These have worked for me, but of course, may not work in all kilns.

6mm heat up at 160ºC/hr

12mm heat up at 110ºC/hr

19mm heat up at 50ºC/hr

25mm heat up at 30ºC/hr

In general, these heat up rates are no more than twice the initial annealing rate for the relevant thickness.  That is, the initial anneal cool for 6mm is 80C/hr; and for 12mm is 55C/hr.  When you get to 25mm, my initial anneal cooling rate is only 15C/hr.  So you can see how the doubling of the initial anneal cool works.

Tack fused and pointed pieces require much more careful heating because of the differing thicknesses within the piece, or the relative narrowness of one end or area in comparison to other areas. The suggestion is that the heat up for these should be at the rates suitable for items at least twice as thick as the thickest part of the tack fused or tapered piece.

Grinder Bit Height

If your grinder bit is too low or too high the diamond surface will not grind the whole of the glass edge. This can lead to chipping of the surface of the glass at the edges.

Example of top of bit almost too low for the glass

A good practice is to start with the bit as high as possible to allow for differing thicknesses of glass. As high as possible is with the bottom of the diamonds just below the platform of the grinder. This will ensure that you can deal with varying thicknesses of glass without immediate adjustment. You can then lower the bit as it wears.

Example of nicely adjusted bit

Of course, you need to ensure there is adequate water reaching the grinding bit to avoid overheating the glass, and to keep the dust from grinding from getting into the air.

Mobile Glass Storage

Sometimes people consider placing their glass storage onto wheels.  It is better to avoid wheels on glass storage for several reasons.

You would need heavy duty wheels to cope with the weight. Glass is 2.5 times as heavy as water, so it does not take much volume to make a really heavy glass case.

Example of mobile glass storage

You do not need to move all your glass at once - a piece at at time is all that is needed. It will be safer, and in the end easier, to build your work bench nearer the glass.

There are risks breakage while moving. The heavy glass store will vibrate the glass within the storage, and any snags or obstructions while moving the glass will increase the risk of breakage.

The structure can become too heavy to move and so defeat the original intention.