Templates of Openings, 5 – Irregular Openings

Irregular openings such as trefoils and other tracery need to have templates taken with consideration on how the final panel can be put into the opening.

In the cases where the whole of the rebate is exposed, it is normally possible to put the panel in as a single whole piece.

So, the template is taken as for any other opening. It is more complex and time consuming as there are so many more sides than in a simple rectangular or circular opening.

Templates of openings, 4

Round headed openings can be considered as a special case of a circle.

The horizontal you must find is the shoulder of the window. This is the place from which the curve springs on each side. The opening is generally vertical up to this point and then begins the curve.

You need to make sure you have marked where this shoulder is on the template. You should indicate any reference points from the frame onto the template.

The join to the lower part of the window must be made obvious. Normally there will be an overlap between the lower rectangular template and this approximate half circle. You need to mark where this overlap occurs, if you do not fasten the two sheets together. This can be done by marking across the two sheets in a few places. This will enable you to join them exactly back at the studio.

Templates of openings, 3 - Circles

Occasionally the window is circular and sometimes an oval. In both cases a template is important. The circle rarely is exact. Take the template in the normal way and then ensure you mark the verticals and horizontals for the opening. You often can use the jointing in the woodwork to help with these. Also mark any other reference points from the opening. Finally, mark which is the outside and which the inside.

This procedure will ensure that you will be able to fit the panel into the opening.

Templates of Openings, 2

Irregular rectangles

If you have found or can see that the opening is not a true rectangle and cannot determine where any right angles are, you need to take a template.

The objective is to make a piece that will fit into the opening without bending or being too small for the space. It will be the same size as the finished panel and so you will be able to put the finished panel into the opening without needing to trim or expand the panel.

First, trim the sheet of material you have chosen to use to a size a little larger than the measured size. Place the uncut side along one of the long sides of the opening. If the opening is a portrait format, place it on the right or left side as convenient to you.

Next, adjust the bottom by marking a line on the sheet. This is where a second person is very useful. One person can hold the sheet in place on outside of the opening and the other do the marking from the inside –in the case of the rebate being on the outside and vice versa if the rebate is on the inside. The marked line should be as close to the edge of the rebate as possible. The special case of an opening in stone will be dealt with separately.

Then take the sheet to a place where it can be safely cut. A long metal straight edge and craft or “Stanley” knife are often the best aids to cutting straight lines. Replace the sheet into the opening after cutting, and make any adjustments to the size and angles of the sheet at the bottom by marking and cutting as necessary.

When the side and bottom are adjusted, start on the other side. Proceed as for the bottom.

When the side is finished, start on the top.

Finally, present the whole sheet to the opening to make sure it slips into place with no snags, or bending of the sheet.


It may be that the opening is too large for a single sheet. In that case you will need to work with two or more sheets and try them together for the final fitting into the opening. You can put them together in the window. You can fasten them together with tape or other fasteners to make one sheet. You can also make two parallel lines both at angles and at intervals across the sheet so that when you get back to the studio you can exactly reproduce the full sheet by matching the marks and then firmly fastening them together. This makes transport of large templates much easier.

You will know that a panel made to a template made in this way will fit into the opening, no matter how irregular the opening may be.

Templates of Openings, 1

If you have an irregular opening, it may be best to take a tracing of the opening. Usually this will be in a larger opening and so a helper may be necessary to hold things.

The material used to take the template must have a few characteristics:
- It must be stiff enough to have the minimum possible bend over the width or height of the opening
- It must be easy to mark with a pencil or other implement
- It must be easy to cut or shape
- It should be light to make it easy to lift it to the opening for the many adjustments that will be required.


A number of materials can be used: stiff card, mounting board, corrugated cardboard, thin plywood, and many other sheet materials. I have found stiff corrugated cardboard easy to use.


More information in this series is at:
Irregular rectangles
Circles
Round headed windows
Irregular shapes
Stone

Measuring a Rectangular Opening.

1 - Measure at both the top and bottom for width.

2 - Measure at the left and right sides for height.

If it is a tall or wide opening measure at intervals and at least in the middle of each side.
So far so good. But how do you know that it is a rectangle rather than a parallelogram? Measure the diagonals – bottom left to top right and top left to bottom right. If these measurements are equal or +/- 5mm you can consider the opening to be a rectangle.

With bigger variations you may set out the cartoon using the measurements for the opening. Still, you need to know where the right angles are, if there are any, to be able to set out the cartoon to properly fit the opening.

So you may wish to take a template of the opening.

Bulging lead panels

There is probably no means by which leaded glass, because of the innate character of lead as its skeleton, can resist its propensity to bend, bulge and sag. Evidence of these occurrences does not necessarily foretell disaster or immediate collapse. Bulging does not necessarily indicate the need for action or re-leading.

There are three basic stages through which stained glass passes on the way to requiring repair;
1. Bulging, bending and sagging
2. Loss of putty and breaking of solder joints
3. Unhousing of the glass from the lead


The points at which solder joints break depends on the materials used.

Since lead, compared with solder, is a resilient material abutting the more resistant solder, breaks will occur most frequently at the junction of the solder with the lead.

With zinc, the situation is reversed. The zinc is of greater resistance than the solder. As a result the break most often occurs on the solder at the point of the zinc junctions.

It is the very existence of resilience in lead which responds to the expansion and contraction of glass that permits the more healthy survival of the glass over the less sympathetic accommodations of either zinc or copper foil. Leaded glass, unlike any other medium, has the unique capability of having its skeleton (lead) replaced, when the need arises, without damaging its body (glass).

Combing Glass

This process is done at relatively high temperatures for fusers – around 925C. It consists of pulling or dragging the surface of the hot glass to produce a marbling effect.

Preparation:
A batt washed ceramic shelf is the best surface. You can use fibre paper on your shelf, but you must be careful to avoid raking deeply enough so that you pick up the fibre and drag it into the glass.

Make a boundary with 10-12mm fibre board on your shelf. You can use strips - for the most efficient use of the board – or cut a shape from a sheet. If you are using strips, fasten them together with wire staples. This will resist the glass flowing at the edges.

Place the glass into the space created by the fibre board. You can place 10mm strips on edge to form very tight lines, you can shingle glass to give broader lines, or you can place the glass in a more random way to give quite different effects.

When shingling or placing glass randomly, it is often best to cut a sheet of iridised clear to lie on the bottom to ensure you have enough depth of glass. Placing the iridised side of glass down toward the shelf provides an additional release, and can give added interest to the back. Anything less than 8-10mm thick leaves the glass pulled away from the edges in the direction of the combing.

Firing:

The initial temperature rise can be fast because the glass is made up of narrow strips. No bubble squeeze is required for the vertical or shingled strips, as there are easy ways for the air to escape. Randomly placed glass should have a bubble squeeze at around 650°-675°C for 30 minutes at least. Otherwise you can fire at about 300°C/hr to 925°C.

You need to programme a soak at that temperature for approximately 120 minutes. This soak allows you to do the combing and have the kiln recover temperature without needing to re-programme. When the combing is finished you cancel the soak after the kiln recovers to 925°C (which allows any peaks generated during the combing to settle down).

Allow or programme the kiln to cool as fast as it can to the annealing temperature and soak for 120 to 180 minutes. Set the annealing cool at 30°C/hour down to 450°C, then 60°C/hour to 370°C and finally at 200°C/hr to 21°C.

Combing:

Safety first. You must do you combing in a kiln that has a safety switch to turn the power off once the lid is opened a short way. If your kiln does not have such a safety device you should reconsider your desire to comb in your kiln. Many say you can overcome this by switching your kiln on and off at the wall socket. However, in doing so you also turn off the controller, making it necessary to re-programme your kiln each of the several times you have to reach into the kiln with your raking tool. This is essentially impractical.

The combing tool is a pointed steel rod, bent at right angles to the shaft - often called a rake. The shaft should be of wood to avoid holding a hot metal rod in your hand. Stainless steel rods are best as mild steel can spall and leave flakes of metal in or on the glass. The rod and wooden handle should be soaked in water while the kiln is heating up. The wet wood will not char so quickly as the dry. This bucket of water should remain beside the kiln so you can cool the metal point, when it begins to stick.

The second bit of safety. You will need to wear gear to protect yourself against the heat. A full face visor is important as the heat will singe you hair. You need to have heat resistant gloves. You need to have heat resistant sleeves to go over your arms. You should wear only natural fibres - cotton and wool are best, as they smoke before bursting into flame, giving you some warning that things are just too hot. An assistant to hold the kiln door/lid open while combing is advisable. And the assistant should have the same heat resistant gear that you have.

You begin to do the combing at 900°C. The glass will be soft enough to be pulled by a gentle stroke across the surface of the glass. Avoid digging into the glass. That will pull or push a gather of glass ahead of point. This leaves a characteristic droplet shaped mark in the glass at the end of the stroke. It may also go deeply enough that the kiln wash or fibre paper that is underneath the glass will be pulled up into the glass. Only light pressure is required to do the combing.

You will only be able to do a few strokes with the rake before the temperature of the glass falls and the glass resists movement. When the glass becomes difficult to move, it is time to close the lid and let the temperature recover. You will have to do this numerous times, until you have the look you want.

Another limitation is the speed that the rake metal heats up. When the metal becomes hot, it sticks to the glass. Whenever the rake is not in use, it should be in the bucket of water cooling off, and re-wetting the wooden handle.

You can comb the glass in any manner you wish. To get the traditional feathered look, you need to alternately pull and push the rake to give chevrons in opposite directions. Experienced people sometimes use two rakes – one to pull and one to push - at the same time. You can also rake diagonally across the sheet and even across the previous rakings. Some experimentation will show which effects you like best.

Annealing Open Face Castings

You need to double the annealing time for an open-faced casting over the schedules for the same thickness, because the glass is cooling from one side only.  The usual schedules are premised on cooling from both sides equally. The schedules given for 50mm thick open face castings should be used for a 25mm thick open face casting.

If you could cover your open-faced casting with something of equivalent insulation as the investment around the glass you could go back to a 1" schedule.

So an open-faced casting 25mm thick needs to be annealed using the schedule for 50mm thick castings as follows (for Bullseye glass - make adjustments for different glasses):
482°C for 8 hrs
4°C/hr to 427°C
7°C/hr to 370°C
23°C/hr to 21°C

See the Bullseye chart for annealing thick pieces.

Based on Don Burt’s work

Cutting Oil

Why use a cutting fluid?

No matter how good a fissure is when scored dry, it is better if scored with a liquid between the wheel and the glass. Several good things happen with an "oil" cut and only one undesirable thing.

The bad thing is you have to wash the glass afterwards, but in many cases washing is required anyway.

A good thing is the fluid reduces the effect of healing - the compressive strength overcoming the fracture caused by scoring. It is probable that the liquid seeps into the fissure contaminating it enough to prevent atomic reattachment of the molecules.

Cutting oil reduces chipping and prevents a flaky score line. The oil tends to provide a hydraulic cushion between the glass and the wheel. This allows more uniform transmission of the shearing forces into the glass at an angle dictated by the wheel, not by particles of crushed glass.

It is important to check the cutter wheel is moving freely, since a wheel not rolling freely may skid. Skidding causes abnormal wear to the wheel and subsequently it becomes a skipper.

You should not use kerosene by itself because it removes whatever oil is on the axle.


Prepared from information provided by Fletcher-Terry company

Tilted Cutter Effects

A tilted glass cutter has the effect of changing the angle of the cutter wheel.

It narrows the angle on one side and increases it on the other side. So on the side tilted away from vertical (which is what happens when you look down the side of the cutter) has an sharper angle with the glass. This is likely to produce chips along the cutting line.

The side which is tilted toward the glass has a more blunt or shallow angle with the glass. This produces high stress along the line.

The combination of these two effects make for a rough edge when broken and for break failures because of the stresses being at angles to the desired vertical fissure line.



Prepared with information from the Fletcher-Terry company

Cutting Wheel Angles

These are the wheel angles recommended by The Fletcher-Terry Company for various glasses:

114 to 134 degrees – 2mm float glass
130 to 140 degrees – 4mm float glass
134 to 140 degrees – 3mm to 6mm float glass
148 to 154 degrees – 12mm to 25mm float glass
134 to 140 degrees – stained glass
88 to 114degrees – borosilicate glass

http://www.fletcherviscom.com/home.shtml

Water Proofing of Pattern Pieces

Many people put their pattern pieces onto the glass they are going to grind, or saw to attempt to get a good fit to the cartoon. The water from the grinder makes paper templates soggy and liable to tear or disintegrate so failing to for a good guide to grinding.

One solution is to stick self adhesive plastic on top of the pattern before you cut it all apart. Then you have some protection when you grind.  The plastic sticks to the surface of the paper and resists the water.  However, the water can seep between the glass and the unprotected bottom of the paper or, even if protected with plastic on both sided, through the exposed edge.

You can spray or apply clear lacquer on the paper pattern pieces before attaching them to the glass and grinding. This has slightly better results as the edge is most often sealed better than with two layers of plastic.

You can use clear acetate film (ca. 0.2mm thick) as a completely water resistant pattern. Cut your pattern pieces from the acetate film and stick them on to the glass with blutack or any other gum based adhesive. This works well and does not suffer from the water deteriorating the pattern piece.

Window Measurements

There are a number of measurements that are critical for a good design and a sound installation of window panels.

1. Tight Size: This is the full size of the glass opening with no allowances for expansion and contraction. In a wood or metal rebate frame one would measure from steel to opposing steel or wood to wood; in a stone groove installation, from the bottom of one groove to the bottom of the opposing groove. Depending on the size of the opening, this measurement should be checked in multiple areas; at a minimum at the top, bottom and middle horizontally and at the left and right jamb.

2. Sight Size is the daylight opening or the largest opening that allows light to pass through.

3. Rebate or groove details. With a rebate frame, the depth and the width of the rebate must be measured, as well as the interior return if round bars will be used (this dictates what size bar will fit and how long the bar should be). These dimensions are also necessary to determine the dimensions of the retaining molding if one is to be used. If it is a groove, the depth of the groove and the width of the groove (measured from interior to exterior) are important.

4. Panel Size. This is the ideal size of a panel that will be installed into the opening in question. Typically, this will be a function of the tight size less 3mm in both width and height for a leaded glass panel, to allow for expansion and contraction. One must also recognize if the size varies throughout the frame and make allowance for this as well. With dalle de verre, you need a deep rebate or groove and allow at least 5mm in both directions for expansion.

5. The depth of the rebate or the width of the groove are critical measurements. To allow for a proper installation, allow a minimum of 13mm to be added to the thickness of the panel to provide room for a proper putty fillet.

Based on comments from Art Femenella

6. When measuring older openings and especially doors, measure the diagonals in addition to all the other measurements. This provides a check of all your other measurements and also tells you whether the opening is a true rectangle or parallelogram.

Cleaning Old Leaded Glass Panels

Please note that these procedures do not apply to painted glass.

The materials that you will need are:
· A dust mask to keep any lead oxides from being breathed
· Gloves – latex or similar that fit well and protect your hands from the chemicals
· Mild abrasives such as whiting or bathroom cleaner meant for fibre glass fittings
· Paint remover for paint and varnish
· Brushes – both scrubbing and paint brushes
· Water for combining with the cleaning agents and for rinsing

Cleaning Location
On site
Cleaning is best done with the panel flat. However, it often is a requirement that the panels be cleaned on site. This requires lots of plastic sheeting to catch the water. This should be taped at the bottom of the panel and spread across the floor. Masking tape or similar is best for attaching the plastic, as other tapes can pull paint and wall paper off. You will need lots of foamy glass cleaner to hold the moisture to the glass. Repeated applications of the foamy cleaner followed by clean water will leave the glass sparkling.

On the bench
Cleaning the panel on the bench is most desirable. First, it keeps the water and other cleaning materials from running all over the client’s house. Second, it keeps the pressure of cleaning evenly distributed across the bench rather than risking the bowing of the panel while cleaning in situ. It also allows safer application of chemical cleaning agents. It allows broken lead joints to be repaired at the end of the cleaning.

The main contaminants on old leaded panels normally are dirt, paint and varnish.
A general clean up of the dirt is to scrub. Scrubbing damp whiting on the panel is a traditional method. A more modern one is to use a cream or bathroom cleaner designed for fibre glass fittings. They are quicker and easier, but make sure they are for baths, etc made of fibre glass.

Paint and varnish can be taken off with paint remover. Both glass and paint removers are alkaline so there is no effect on glass. There is no noticeable effect on lead if you do not clean it first. If you must clean the lead, do it last.

There are some precautions you must take when cleaning old glass, especially as the surface of the lead will be a lead oxide that can get into the air. You should use a dusk mask and wear gloves. You should dampen the area around the work frequently to keep the dust from circulating.

The main requirement is that you do not apply these procedures to painted glass or panels that have some painted glass.

Regular cleaning can be done by the clients with a soft brush to keep the dirt from building up.

Butting of leads

Lead came is normally cut to meet up against the adjoining cames. This provides a neat joint that will carry the solder without needing to fill gaps. The easiest joints to make are those at right angles. You can measure or estimate the amount that the came must be shorter than the glass, but it is easiest to use a piece of came the same size as will be passing the piece you are cutting (gauge came). You centre the gauge came on the cartoon cut line near the joint. Using your lead knife you can extend the line of the side of the gauge came to the piece you will be cutting. The mark you make with the lead knife can then be used to guide your cut of the came, as you take it away from the glass.

Those joints with angles have the came marked and cut in the same way as for right angles as the gauge came will give you the correct angle to cut.

Always remember when leading that you lead to the cartoon lines not to the glass. If the glass is short, use the cut line to place the gauge on, not against the glass. If the glass is too large, adjust its fit.

Glass Cutter Wheels

There are many different types of glass cutters on the market today. Choosing the proper cutter is the most important decision you must make, as it will be a large element of how you enjoy scoring and breaking glass. There are some elements that you should consider in addition to the style of the holder.

Steel Wheel Cutters are inexpensive but usually not long-lasting. They must be replaced frequently as they easily become damaged.

Tungsten Carbide Cutters are more expensive than steel wheel cutters, but far outlast them in durability. Self-lubricating cutters eliminate the need to constantly lubricate your cutter between scores.

Wheel Angles. There are steel wheel cutters which are good for general purpose cutting, production cutting, or pattern cutting. Some are good for cutting thinner glass, others for thicker glass. The angle of the bevel on the wheel determines this and differs from model to model, although some offer wheels of different angles. Pistol grip cutters produce more pressure than others.

Identifying the coated side of glass

Dichoric and iridised glass can present difficulties in identifying the side that has the coating. For some applications it is important to know which is the coated side to place it up or down or even to make sure the pieces are all the same way up.

Several methods are possible:

On coated clear glass you can use a pencil or other pointed object. Hold the glass so you're looking a glancing angle then bring a pencil down onto the surface. The coated side will show a clear reflection of the pencil tip and the backside will show a gap, or multiple image of the pencil tip.

If the glass is dark or black this method will not work conclusively. Instead you can use grozing pliers to nibble at the edge of the glass. The surface that shows damage to the coating is the coated side. If there is no damage visible to the coating, the other side is the coated one. You could mask the glass and sandblast a small corner. If the coating blasts away, that is the coated side. If not the coating is on the other side.

Having gone to all this trouble, mark up the glass side with a permanent marker to identify the coated side. Also mark each piece cut from it so you do not have to repeat the test on each cut piece.

Annealing open face castings

You should double the annealing time for open faced castings. The glass loses heat to the kiln from the open surface faster than through the bottom of the casting through the investment and any base that the casting is sitting on. If you could cover the open faced casting with an insulation of equivalent thermal value as the investment around the glass you could go back to the schedule for the actual thickness of the glass.

What is Waxing Up?

I have had the question above asked. It seems appropriate to respond as part of the tips section, as I had made unwarranted assumptions in posting the waxing up recipe.

Waxing up is the process whereby the cut and sometimes partially painted glass pieces are assembled on and stuck to a glass sheet - called a glass easel - before raising it to a window to get the light that it will receive when installed. This allows you to see what the current state of the window is and how it would look when installed. It shows up weak areas, or pieces which are not really compatible. Although it is used mainly by those who do a lot of painting on their glass, it is equally valuable to assess the composition of a leaded or copper foiled piece. It does ensure that you do not get surprises when you have finished a piece.

The wax used is sticky and stiff enough to hold the glass, but not so sticky as to be difficult to get the pieces off the glass or the wax off the pieces of glass being prepared.

Also some users of the glass easel method paint representations of the lead lines on the back side of the supporting glass to ensure the values of the lines are appropriate for the amount of detail for the various areas of the panel.

Soldering Fragile Pieces of Glass

Heat transfers to the glass during soldering. Normally this does not produce any difficulties. However with slender pieces, deep curves, or band saw cuts, the heat generated by soldering can crack/break the glass. This means that you need to ensure that you do not linger for a long time on the solder beads along these kinds of pieces.


You can do several things:

Solder roughly at first, and then continue soldering somewhere else on your piece, to let the heat of the solder dissipate before finishing soldering by filling the gaps in the bead.

Create the bead in a single relatively swift pass. It has to be slow enough to produce a bead, but not linger in any area. The bead should not be so large as to turn over on itself. It should be similar to a quarter or at most a third of a circle.

Build the bead up with a series of “pats” along the copper foil joint. This involves putting a dot of solder to the copper foil tape and resting long enough for the solder to spread to its natural dimensions, and then place another dot at the leading edge of the first and so on until you reach the end of the line. This provides a relatively cool method of soldering. Its disadvantage is that it leaves a number of “tide” marks at the cool end of the bead. These can be changed to a single tide mark by re-melting the solder at that end.

Sharp Corners on Fused Rectangles

Often single or two layered rectangular pieces have sharp corners on the top or at the bottom.

This is caused in the case of the single layer, 3mm or less, piece by the glass trying to pull up to 6-7mm. 

In the case of the two layer, ca. 6mm, piece the sharp area is just at the bottom rather than the top.

In both cases the sharp corners on square and rectangular items 3 or 6mm thick can be avoided by nipping a very little off the corners before firing.

Lead Framing

One option for framing, especially where the edges are not rectangular is to use lead. The lead touching the glass or copper foiled edge should be 10mm flat came. This allows you to insert a 5mm mild steel rod shaped to the outside of the panel. This is then covered by a 13mm flat came. The came is smoothed by gentle pressure on the upper and lower flanges with a stopping or lead knife to bring the two flanges together. This gives a pleasant finish to the edge.






by Gene Mallard

Finger Protection While Grinding

Various methods of protection are used:
Finger stalls,
Taped fingers,
Altering the fingers used to press the glass to the grinding bit,
Gloves – but they have to very tight fitting to avoid getting caught in the spinning bit.
Duct tape,
Grinders' Mate.

Prevention
The sore fingers are usually caused by tiny cuts from the glass. So, all these methods are ways of putting something between the glass edges and your fingers. More importantly, you need to think about your practice if you are getting sore fingers while grinding.

The first thing is just to lightly grind all the way around the piece first. This can be quick, and should use minimum pressure. This will remove any sharp edges.

If you have to press hard to achieve the effect you want, it may be that your grinder bit is badly worn. It may also be that you need to have a coarser bit to achieve the amount of grinding that you need.

You should not be pressing hard in any case. This will wear out bearings on the motor and reduce the life of the bit. You should use medium pressure and allow the diamonds on the grinding bit to do the work. Fine work requires a fine grit, removing a lot of glass requires a coarse bit, not more pressure.

If you have to remove large amounts of glass, you need to review the accuracy of your cutting. You should not be relying on the grinder to do more than tidy your cuts.

Remedies
There are several remedies to relieve the soreness:

Cucumber melon antibacterial hand lotion
Vitamin E.
Tea tree oil
Germolene

Glass Grinder Use

Glass grinders are very handy tools. They mainly consists of a spinning diamond coated cylinder (the bit) extending above a grid surface that can rapidly and accurately grind glass to the desired shape.

Don't purposely cut glass large with the intention of grinding. Ideally no grinding would have to be done. It should be used only for minor adjustments or for grinding tough-to-cut inside curves.

Bits
The diamond bit must be kept wet in order to reduce wear on the diamond and prevent glass dust from developing and being inhaled. There are several grits available. "Fine" grinds slower but leaves fewer chips in the glass. "Coarse" grinds very fast but leaves larger chips. "Standard" is a central compromise.

Water reservoir
Ensure there is water in the reservoir before starting any grinding. Empty the reservoir daily. This keeps the water from producing a smell, and allows you to clear the glass residue from around the grinding bit.