Fitting Glass in Leading

Even though you think you have cut the glass exactly to size, it always seems that some adjustment is needed to areas of a piece to fit both into the lead came and be within the lines of the cartoon.

The temptation is to trim the glass to the amount of overlap of the cartoon line.

Note the extent of the overlap of piece #7 on the right.

In the above photo it would seem to be easy to just trim the straight line off the piece.  If you look carefully at the left side of the piece, you will see a gap between the glass and the lead came.  This means something more is happening than just being too large.  If you were to cut the glass down to fit within the cartoon line at this point you would find it too small in the end.

To find out what is going on underneath the lead came, you will see that I have made a line with a felt tip pen at the edge of the came.

When pulled out from under the came the line shows there is more glass under the came at the lower left than the middle left.  This indicates that the lower left needs to be adjusted rather than the right edge.

Groze or grind the glass to an even amount of glass between the felt tip line and the edge of the glass. This may have to be done several times to get the proper fit.  In this case I used the grinder because of the extreme texture of the glass.

This photo shows the glass fits at the bottom right, but needs more adjustment at the top right.  But it does fit under the came at the left side now. The amount of adjustment can be judged by marking the glass and grinding a portion away to fit.

An alternative example of the advantages of checking the glass is fully fitted within the came is shown here.

Here the blue piece shows it is slightly too large at the top.  The temptation is to refine the edges and reduce the size slightly.  Before doing that, it is advisable to check on how the glass is fitting into the came.  Again, run a felt tip marker along the edge of the came before pulling it out to adjust the size.

This shows there is a little bit of glass not broken off at the left side of the bottom tip.  Also, there is a larger space between edge and felt tip mark on the right than the left.

The first thing to do is to take off the excess glass on the lower left of the bottom tip and try the piece again.  That may be enough to allow the glass to fit into the came and match the cartoon.

The excess glass was ground away and a little taken from the bottom right side too.

This shows that just removing that small piece of glass has allowed the blue piece to fit correctly into the came and to fit the next piece of came to be placed without causing the panel to grow in size.

When a piece of glass is too large in leading, you need to check that it is fitted properly within the came, before adjusting the outer edges.  A method to do this accurately is described.

Leading - the First Glass Pieces

After establishing the perimeter lead cames, place the first glass piece into the corner formed by these cames. 

You only need to establish one vertical and one horizontal came to begin with. The other two will be placed at the conclusion of the leading.


Normally, you will be working from the lower left corner toward the upper right corner of the pattern if you are right-handed. The reverse is the case for left-handed people. 

Hold each piece of glass in place with some scrap lead and nail. The scrap lead will prevent the nail from chipping the glass. It's important all glass is held in place with nails so no shifting occurs while working in another area of the panel.

Fitting the rest of the glass to the cartoon is described here. 

Revised Feb 2020

Tucking Lead Came

It is most usual in many countries to butt lead cames against one another. In continental Europe the tucking of cames is more common. In this process, which has the advantages of speed and accuracy, the came is first fitted to the glass and then cut at the edge of the glass.

The first step is to cut the came to the appropriate angle to meet the lead to which it is to be joined. However before presenting the cut came to the joint, one end is lightly tapped with a small hammer to slightly curve the end of the came. This allows it to slip inside the leaves of the came to which it will be soldered.










The came is then shaped to the glass as normal. However, rather than removing the came for the next cut, the came is cut to the length of the glass, often using the glass as a guide. This end is then supported on the lead knife and tapped with the hammer to curve the end, ready for tucking into the next piece of came. Care is required so that you don’t crush the came and break the glass, nor miss the came and hit the glass or your fingers. With practice, there are few accidents.

Diagramatically, the tucked lead looks like this:

Tucking lead provides very accurate joints with no gaps for solder to fall through. Some argue it provides a stronger panel as the hearts of the jointed cames almost meet. The main immediate gain is quicker soldering.

Dressing the Cames - part 2

Of course, it is not enough just to dress the came at the start. There is an analogous procedure after the whole panel has been leaded, soldered and cemented.

In this instance the term ‘dressing the cames’ means to close or bend the leaves/flanges of the came toward the glass. It provides a neat rounded appearance to the lines, traps the cement you have already added, presents less area for the rainwater to collect, and makes polishing easier. It is also the time when you may break the glass by putting too much pressure on the glass, so be careful!

Dressing the cames is done with an oyster knife or fid. It is best to avoid metal and better to use wood sticks or plastic tools. The pressure is placed on the came rather than the glass. Run the fid lightly at a shallow angle along each flange of the came. It is helpful to use a finger of your other hand to guide the fid along the cames. You may want to do this several times, as repeated light pressure will cause the flanges of the came to move gently toward the glass with less risk of breaking the glass. This can only be done while the cement is pliable. If it is done after polishing, you will need to re-do the polishing, as it will make the edges of the came silvery rather than shiny black.

Snugging the Came to the Glass

It is important to have the came fit snugly to the glass (assuming the glass to be the right size and shape). If it does not, the panel is likely to grow beyond the intended dimensions.

To ensure the came is tucked snugly against the glass, you use a fid of firm material (wood or plastic, for example) to press against the heart of the lead. You can press directly toward the glass, or make multiple passes along the length of the came to ensure the heart is touching the glass all along its length.

You should avoid steel tools, because you may cut the lead, and if the blade is long you will not find it easy to fit along all of the curves.

Fitting the Glass to the Cartoon

Often you find that the next piece of glass does not fit properly. Possibly it rocks a bit in the came’s channel. Possibly it is simply just a little too big.  Wait! Don't adjust the piece just yet. It may not be the problem.

The first thing to do is to take the too-large piece of glass out and remove the came it fits into, to ensure the previous piece of glass is not too large. The glass should not overlap the cut line. If you have drawn your cut lines to 1.2mm (1/16”) you should see only the faintest line of paper between the glass and the dark cut line. 

If the glass seems too large, check that it is firmly in the channel of the previous came, as sometimes the glass catches on the edge of the came and does not go into the channel.

If that piece seems too large, the next check is to determine whether the apparently too large piece of glass really fits the cartoon cut lines. Place the glass inside the cut lines. You should see a faint line of paper between the glass and the cut line.

When you are sure both pieces of glass are the correct size, put the came back between them and check again. If the glass is still too large, check the length of the came. Make sure the came butting onto the came separating the glass is not too long. This is a common reason for lead panels to grow beyond their initial dimensions.

If the glass is the correct size and the butting cames are correct, replace the came. Put the too large piece of glass into the came and position it so it has the best fit to the next cut line. 

Do not be tempted to start reducing the glass at the visible portion.  After all, you cut it to the right size. It may be that the fit under the came is not very good.

To check use a felt tipped pen (Sharpie) to run along the edge of the came, marking the too-large piece of glass. Take it out and check on where the line is farthest from the edge of the glass. That is where you need to reduce the piece.

The nail points to the area that needs adjustment

When you have reduced the "high" spots on the glass so it fits under the came evenly along its length, you can begin to adjust the outer edge, if necessary.

Leading Tight Curves

Sometimes it can be difficult to get the lead came to conform to the curves of the glass, especially on compound curves.  This is a method to make the leading more accurate.

When leading tight inside curves, bend the came into a tighter curve than is needed for the glass. Then roll it into the glass. Finally, run your fid or stopping knife along the heart of the came to ensure it is firmly against the glass. All this helps the came to fit snugly into the curve.

Dressing the Came

This is a different kind of dressing than what you do in the morning. It relates to how easy it is to slide the glass into the channel of the came.

If you have consistent difficulty in sliding the glass into the came, you should consider dressing the came before use. Dressing the came consists of running a fid or other hard material along each of the four flanges of the came. In doing this, you are pressing each flange in turn down against the bench or other smooth surface.

Dressing the cames gives a slight bevel or ramp for the glass to slide over the edge of the came and into the channel of the came. You can dress the whole length at once, or as you cut the pieces off from the main length. Dressing shorter pieces is less likely to bend the came away from the straight.

Leading Small Circles

Putting came around small circles such as lenses and small bullions often leaves an irregular curve. There is a way to avoid this.

Use oval or round came to reduce the kinking of the leaves of the came. As there is less material at the edges of the leaves of oval came, there is less kinking than on flat came, where the thickness of the leaves is constant.

Begin to form the lead round the circle, about half way. Then take the circle out of the came and cut, at a right angle to the length of the lead, at an angle from top to bottom. The degree of the angle is not important at this stage, only that you can repeat the angle – so it must be fairly shallow and natural for you.

Put the circle back into the came and continue to form the came round it until you meet the angled cut at the beginning. Again at right angles to the length of the came, cut a repeat of the angle.

Then fold this end toward the other end. Push the two angled ends together. If they slip up and down from each other, the came is too long. Open the came and cut a sliver off.

Try again until they meet with very little “slippage”.

Then the piece is ready to put into the panel. Place the join at a lead joint so you don't have an additional solder spot.

This technique can be used for small ovals too.

Leading - Establishing the perimeter

The first thing to be established about the panel is the placing of the came that goes around the edge of the panel.

Fix your cut line cartoon to the work board.  Usually a long strip of masking tape on all the edges will be sufficient.  To establish the placing of the battens, which will form the frame for the leading process, you need to determine the spacing from the cut line.

This shows the initial battens in place and ready for the final two battens to be put in place before soldering.

To determine the size of the off-set of the battens you should cut a short piece of the came you will be using for the outside and use that as a guage.  Place the heart of the came on the outside cut line near one end and move the batten to the side of the came.  Nail that end of the came to the board.  Move the guage came to the other end of the cut line and do the same with the batten as you did for the other end.  Establish one other batten at right angles in the same way.  Then you are ready to place the cames.

Make a straight cut across the came to be used for the outside and put that trimmed end into the corner and along the vertical wood strip. The lead should extend beyond the cut line to accommodate the length of the upper horizontal came. The minimum length must be longer than the width of the perimeter came that will butt against it. If it is even longer, the extra can be trimmed off after the leading is complete or after soldering.


Next butt a trimmed piece of perimeter came along the horizontal wood strip. This one should be shorter than the cartoon. It should be half the width of the perimeter cames to allow the vertical came to butt against it. The reason for having the vertical cames running from bottom to top is that there is a fraction more strength in the heart of the came going all the way to the bottom of the panel, rather than resting on the flanges of the came.

This is how the finished perimeter cames will appear:

These perimeter cames should be held in place with horseshoe nails. Try placing the nails only where a lead line will be soldered in order to cover any nicks the nails might make. Alternatively, you can place the nails at the ends of the perimeter cames to keep them from sliding vertically or horizontally.


If you want to have mitred corners, this post will show you the method.

The next stage of placing the first pieces of glass is shown here.

Leading acute angles

Most of us like flowing lines in leaded glass windows, but these often give very acute angles to be leaded up. One way is to avoid creating intersections by using passing cames.  

But, if the cartoon does not allow for passing cames in acute joints, you have to consider how to cut the came to butt well against the next came. The easiest, but most time-consuming method is as follows:

Determine what the length of the came must be to reach the end of the joint.

Mark your lead there.

Determine what the shortest part of the came will be at the joint and make a faint mark there too.

Cut the came at the first (longest) mark.

Use your lead dykes to cut the heart out of the lead, leaving only the flanges. This is done from the end to just beyond the faint mark you made to indicate the shortest part of the joint.

You then need to smooth the two flanges where the heart was. You can use a fid or your lead knife to draw over the rough interior of the flanges. This enables the flange to be inserted below the came already in place, or to slide the new came over the modified came.

You can trim the upper came flanges immediately to conform to the angle of the joint or do it when the whole panel is leaded. Make a mark with a nail or your lead knife along the edge of the un-modified came. Then raise the flange and use your lead dykes to cut the flange along the line. Fold the flange down to butt against the passing lead and it is ready to solder.

False Lines in Leaded Glass

False lines are used in leaded glass where the design calls for an angle that cannot be cut into the glass. This includes right angles and even more acute angles. E.g., the petals of a fuchsia flower. 

The design would call for an angle of about 60 degrees. This is impossible to achieve through hand cutting. So the glass is cut in a curve and the cames on the side and bottom of the petal have their hearts cut out so they overlap each other. 

In the example above, the red petal points would be cut rounded, so that the clear glass below can be rounded as well.  The came or foil is extended beyond the glass to give the visual points required.

The overlap is then trimmed to the shape of the outside of the petal. When soldered, the appearance is of the glass being cut at the angle required for the flower.

At other times, the requirement is for a line to go into a piece of glass, but not all the way across. As in this stained glass panel by Justin Behnke.  The hanging lines are those on the lower left of the panel, giving a great flow to the whole.

Again you cut the heart out of the came, and overlay the smoothed lead onto the glass. You can use just a little silicone to hold the lead in place until you finish cementing. After this you can lift the piece of came and use silicone or epoxy resin to firmly attach the came to the glass. You do not want to do this before cementing as any excess of glue will be made dirty by the cementing process and be very difficult to clean up.


There are also times when you may want to have a silhouette, you can cut it out of lead foil and solder it into place. This allows intricate shapes to be made when a dark representation of the shape is required. If the panel can be seen from both sides, the overlays should also be on both sides. These should be glued to the glass just as for cames.

Further information on removing the heart of lead came are given in this post on leading of acute angles.

These principles can be applied to copper foil too.

Came: Straighten vs stretch

In dealing with lead came there is often reference to “stretching the lead”.  This frequently leads to emphasis on making the lead came longer. However, this is a misinterpretation of the phrase.

The object in pulling on the lead is to straighten it.  No more effort needs to be put into the lead once it is straight.  In fact, further stretching can lead to weakness.

The upper strectched came has an orange peel texture and the lower straightened does not

You will see an “orange peel” texture on the surface of the came when it has been stretched beyond its tensile strength.  This indicates considerable weakness in the metal.

The upper piece illustrates the visual effect of over stretching leading to the weakening of the came

A test to show relative strengths in stretched and straightened came uses two short pieces of came from the original pair.

After three 90° bends from the straight to a right angle, the stretched came has begun to break.  The straightened came is deformed at the inside bend, but not broken. 

This test shows stretching the came to the extent that there is an "orange peel" appearance to the surface, dramatically weakens the lead came.  Only draw the lead came to make it straight, not to lengthen it.

When you are trying to get kinks and twists out, there is a point between straight and stretched where you begin to weaken the came instead of simply making it straight. There is a point in straightening linked or twisted lead that goes so far in trying to get it straight that the whole is weakened. When the orange peel appearance shows on the came, you have stretched to the weakening point. 

It is often better with kinked and twisted came to cut out the damaged portions and straighten the rest.

Soldering Fumes

Exhausting Soldering Fumes

Health and Safety

The health and safety of working with lead and solder are a great concern of many people.  Greg Rawls, the acknowledged expert in glass working health and safety, puts soldering and lead work in perspective.

Soldering lead came for stained glass does not usually present an inhalation hazard if the area is well ventilated and you are using an iron and not a torch. With normal soldering, you are melting the lead at temperatures that are NOT hot enough to create a fume.
Lead fume is the inhalation exposure issue. Fumes are very small respirable particulates that are made with heat. Liquid chemicals give off vapours.

Avoid exposure by ventilating the area when soldering, especially if using a torch instead of an iron. Open a window and turn on a fan!  Wash your hands thoroughly when finished working with lead. There are specific products for this purpose.

Use a P95 or P100 respirator when concerned about lead exposure. 

http://www.gregorieglass.com/chemicals.html

There are commercially made fume traps which often have an activated charcoal filter and can be effective.  A simple desk top fan blowing away from you can be effective in well ventilated areas, if you are working on your own. (otherwise it blows the smoke toward others.)

An example of a fan drawing fumes away from the person soldering

Making a fan

Exhausting fumes while soldering is a safety issue. If you happen to have an outdoor screened-in studio a simple fix can be had with a computer fan! You can scavenge such a fan from an older used computer ready for disposal. Simply cut four timbers 50mm square or 25mm x 100mm to fit around it as a box. Attach a long electrical cord to it with an approved plug. Attach a screen to both sides. Plug in. An additional feature is to attach an activated charcoal filter (as used for cooker hoods) to the front of the fan. This removes particles and some fumes.

Positioning

Always set a fan to draw fumes away you, generally pointing it so that it is blowing the fumes in the same direction as the larger air flow in the studio. A very large fan doesn't always do the job alone, since the fumes seem to rise and find your nose. However, with an additional small fan sitting right next to where you are currently soldering, the fumes just move away.

Wearing an appropriate dust mask as illustrated by the Bohem Stained Glass Studio is the best solution.

Stretching Lead Came

Stretching lead came is so ingrained into the literature and general thought that it is difficult to regain the purpose of the practice.  But I will try.

The purpose is to straighten the came

Purpose

The purpose of putting the lead into a clamp and pulling on the other end is to straighten the lead came.  It is much easier to work with a straight came than one that is curved or kinked.  It gives visually straight lines, it provides smooth and sinuous curves without interruption in the line of the curve.

It is said that some came is “pre-stretched”.  This is really the result of alloys contained in some lead to make it stiffer.  It still needs to be straightened before use.  If the lead came is already straight, you do not need to do anything else before using it.  If you drop or otherwise accidentally bend the came, you need to straighten it before continuing.

Stretching can weaken the came 

Stretching

Pulling on the lead came is not to stretch it, it is to straighten it. Stretching the lead can make it weaker. Lead drawn beyond its structural limits will break.  But you can weaken it before the break. You can test for this weakening of the came by observation. If you see "alligator" marks on the surface, you have weakened the came by putting too much effort into the pull. Straightening the lead must avoid so much force as to weaken the structure of the material.

Straightening not Stretching 

Straightening

The amount of effort to be put into straightening the lead came is just enough to make it straight. This will vary depending on how straight the came is at the start.  The reason for drawing the lead toward yourself is that you can see as you look down the length when the lead came is straight. If you are pulling vertically, it is more difficult to see when the lead becomes straight. 

If the lead is badly kinked or twisted, it may be best to cut that section out. If you continue to pull to straighten a difficult section, you can weaken the whole length of came.  First, ease the kinks and twists out as much as you can by hand. Then do an initial straightening pull.  This initial straightening pull will show where the problem(s) lie.  You can cut that section out and straighten the remaining pieces without stretching the lead to the point of weakness.

Safety

Of course, you must employ some basic safety rules.  Make sure the lead is securely clamped.  In the cleat style lead vices, you can give the lever a thump with the pliers to ensure the teeth are set into the lead before pulling on the other end.  Other vices need to have other ways to ensure that the end is held securely.

The other basic safety rule is that you should brace yourself against any break of the lead, or slip from the vice.  One foot should be placed behind you so that in case of breaks or slips you will not overbalance and fall.  This has the added advantage of ensuring you cannot put your body weight into the straightening effort.

There are other common sense rules, such as gloves, removing obstructions behind you, etc.

Conclusion

Remember that the purpose is to straighten, not stretch the lead came. 

If you are putting your foot on the bench to add force to the puilling of the lead in a vice on the bench, you are putting too much effort into the job and risk falling when the came breaks or slips out of the vice.  If your whole body weight is being used to draw the lead toward you, you are using too much force. If you can see signs of a pattern developing on the surface of the lead, you are using too much force.

Straightening the came is not an exercise in a workout programme.  It is a steady firm drawing force until the came is straight.  If you have to use more than usual force, stop and figure out why.  Cut out the difficult section so you do not weaken the came.  Then straighten the remainder and continue leading.

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.