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