Foiling Space

There are a lot of views on what amount of space is required between copper foiled glass pieces.  Some say the pieces should be tight, others that a consistent space is needed, and some who say that variable spaces are fine.

It is necessary to consider what holds a foiled panel together.

Adhesive

The foil is supplied with an impact adhesive which helps keep the foil attached to the glass before soldering.  However, the heat of soldering deteriorates the adhesion of the glue.  If you must take a foiled piece apart you will find that the adhesive is sticky rather than firm. Also, the adhesive will continue to degrade during the life of the object.

Solder

The solder bead is significant in creating the matrix required to hold the panel in one piece.  The bead on each side holds the glass in place and resists deformation away from a single plane. This resistance is significantly reduced if there is not a fin of solder connecting the two beads.  The beads and the fin of solder form an “I” beam which together resists movement of the glass.

Strength

To form that “I” beam there does need to be space between the foiled pieces. It does not need to be wide, but it does need to be enough to wiggle the pieces.  This will allow the solder to flow from one bead to the one on the other side, forming a strong “I” beam.

In vertical panels, the glass is the strong element.  The solder lines serve to hold the matrix together.  Where people indicate the strong border will keep the whole panel from falling apart, they are correct in part. But, if there is not a sufficient “I” beam between each piece, the whole panel is subject bowing, either from wind pressure, vibration or mechanical pressure from handling.  Therefore, you cannot rely on the border to make your panel strong and long lasting.

Dissent

Some take the view that there will be enough unintentional spaces created between pieces to allow the fin form between beads intermittently.  But the gaps in the “I” beam due to tight fiting pieces will make it much weaker than a continuous bridge between beads.  The existence of gaps puts greater pressure on the solder that does bridge between beads.

An example was provided for me in a lamp brought in by client which spontaneously fell apart one evening.  (Not made by me, I add). The upper band of glass remained attached to the vase cap, but separated from the rest of the shade.  Fortunately, it fell straight down and only a little of the bottom edge was broken.  Investigation showed there was very little solder between pieces, although there was a good bead on each side of the lamp.  The lamp pieces separated, in different places, at the foil-glass interface and elsewhere at the foil to foil interface.  This indicates there was little or no solder where the foil remained on the glass, as the adhesive is much weaker than even a thin fin of solder running between the inner and outer beads. This case is an example of the need for a fin of solder to be formed between the beads on either side to provide a strong, long lasting object.

Heat Cracks

There is sometimes a fear expressed that tight fitting of foiled pieces can lead to heat fractures when soldering due to expansion.  Yes, when soldering pieces with a lot of variation in width, you do need to move reasonably quickly. Come back later to improve a bead if you need, to avoid overheating the glass.  Even the thin copper foil can transmit heat along its length, which reduces direct heat transfer to the glass.  Mostly, breaks occur from dwelling too long in one place with the soldering iron. It may be better to tin the foil all around the suspect piece just before running the bead.  This will warm the glass around the edges in preparation for the greater heat of laying down the bead.

The main point is that the solder needs to connect the beads on either side of the glass to provide a stable, strong and long-lasting piece.

Foiling Tight Curves

Foiling tight curves often leads to splits in the foil.  This note gives information on how to generally avoid the splits and a repair method when they do occur.

Make sure the piece of glass is free of dust and oil and that there are no sharp ledges. Find the flattest part of the glass piece to begin the foiling.

To get the foil to stick to the curve and fold over onto the glass with the minimum of tears, use your fingers first to burnish the sides of the foil onto the piece of glass beginning on the outside curve.

As you move to the inside curved portion gently and progressively ease the edge of the foil with your finger toward the surface of the glass. Easing and burnishing one side of the curve at a time will give you better results toward getting the foil to stretch onto the glass without tearing the foil.

Finish by burnishing the foil down using a fid. This helps keep the foil firmly adhered to glass through the soldering.

Dealing with splits
Tears in the foil line happen. Clean up the broken foil lines with a craft knife and the solder line will look nicer when project is finished. You can also patch the tears by placing a small section of foil over the broken foil.  Place the scrap on one side, burnish it, and fold it onto the edge.  Ease the foil onto the second surface and burnish all the surfaces again.  Then trim the scraps that extend beyond the rest of the foil with a craft knife.

Foiling and Soldering Small Pieces

There are several approaches to dealing with small pieces in copperfoiling:

No-foil approach
One approach is to have some of the pieces held in place by over-beaded solder without foil on the tiny piece, but it is patchy at best and likely to lose pieces in the long term.

Bevel approach
A very good and strong approach is to partially 'bevel' the edges of each piece on both faces. Grind at 45 degrees until the very edge is only 1 mm thick. Then use foil that is 4 mm wide for 3mm thick glass. For 4 mm glass, you will use 5.4 mm foil. Make sure that the foil covers only the bevelled edges and does not extend outside them.

Solder into the 'V' formed by the bevelled edges. Don't over-fill the joints as you don't want solder outside the 'V'. It also is best if the panel is supported underneath the area being soldered by a wet sponge to more quickly cool the solder.

With the solder contained by the 'V', the solder lines will be of constant width throughout the piece. Best to practice this technique on some scraps before you start the main job.

This approach will minimise the amount of light blocked by the foil - important with tiny pieces - while still providing the strength of fully foiled pieces.

Triming approach
If you have to have really small pieces, just foil them as you would any other piece, and burnish it as normal. Then take a very sharp craft knife (Exacto or similar) and trim the foil so that just a little tiny bit of foil is on the front and back of the piece.

No glass approach
Tiny pieces are really tedious to work with. So if the piece is going to be black or really dark, for example a small hummingbird's beak, or a bird’s eye, don't bother with glass but just fill the space with foil and solder.

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.

Filling Gaps Between Glass Pieces

Gaps along the bead line

When you have a gap between pieces of foiled glass, fill the gap with small pieces of lead or copper foil tape that has the adhesive side folded together. These will have to be cut to a width of just less than 3mm to keep them from projecting above the surface of the glass. This material helps to fill the gap and reduce the amount of “melt through”. Put a bit of masking tape on the top surface of the gap and turn the panel over.

Solder the back first. You can do this with 50/50 or 40/60 solder as it does not change from solid to liquid and back so quickly as 60/40. (See melting points of solders.) However the masking tape will keep the solder from dripping through if you apply too much heat. When you have finished soldering the back, apply masking tape to the now filled gap and turn over.

When completing the soldering of the top, you will need to take care to avoid over-heating the solder filling the gap. Over heating will allow the solder to melt through the existing solder and flow along the back. Usually, an application of dots of solder next to each other avoids transmitting as much heat as running a bead will. When you have passed the gap area, you can continue running the bead in the normal way.

Gaps between pieces

When you have gaps between glass that cannot be cut or re-cut, such as globs, fill the gap with a piece of lead or copper foil sheet cut to the size and shape of the gap. This is better than folded up pieces of lead or foil as it carries the solder over the gaps to the foiled pieces of glass. It allows for a smoother surface, and uses less solder.

Note:
Remember to avoid moving the panel for a while, as the large solder bead will require longer to become solid.

Exposed Foil

After soldering, inspect the solder seams for small areas or strips of copper foil edges that aren't covered with solder.

If this exposed foil is where you want the solder bead to be, you need to clean the foil and re-apply solder. Usually scrubbing with “000” steel wool is sufficient. If, after scrubbing and applying flux, the solder still does not stick, you need to wash the piece and after drying, scrub the exposed foil, re-apply flux and solder again.

If the exposed foil is surplus or where you do not want any solder, take a craft knife, and carefully trim off the exposed foil.

Liquid Flux Use

Liquid Flux

It is important to put the minimum amount of liquid solder on the copperfoil seams. A surplus of liquid flux will bubble and splatter, leaving holes in the solder bead. Cutting your flux brush about in half, at a slight angle will reduce the amount of flux on your brush and ease the application.

Pour a small amount of flux, just enough for the task at hand, into a small container. Don't pour the leftovers back into the flux jar, it will contaminate the rest. Do not use the lid of your current flux jar, as it should be sealed at all times so it won't become sticky by evaporating.

When finished soldering, wash off the flux by washing it with warm water and a very little dish washing liquid and a soft sponge, then rinse with water. Clean your flux off right away after you finish soldering. Flux will oxidize your solder seams if left over time. It also becomes more difficult to remove when it has begun to dry.


See also:
Flux, an introduction
Fluxes, a description
The Purpose of flux
The action of fluxes
Soldering fluxes

Soldering 3-D Pieces

When soldering 3-D pieces together, first tack the panels together with a single tack at each end. If it later turns out that there is an alignment problem, it is much easier to dis-assemble a few tacks, with a piece of paper inserted into the space between the pieces of glass and moved up into the molten solder while your iron is at the tack joint. The paper will strong enough to move through the solder, separating the two piece of glass.

Once your 3-D piece is tacked together and looks OK, turn the piece over on its side, and, using 50/50 or 60/40 solder, fill in the inner seams, moving the piece around. Be careful to support the piece with boxes or blocks and by holding it at the top part above where you are soldering, to prevent the piece collapsing.

Once the inside of the piece, say a panel lamp, has been soldered smoothly with 50/50, turn the lamp over. Get a few boxes or similar supports to prop the lamp up against, and make it so that there will be a level solder seam. Using the 50/50 solder again, fill in the seam. It doesn't have to be perfect, at first. Do all of the seam filling first, to ensure the stability of the piece. Then go back with 60/40 solder and, again making sure the lamp seams are level, finish by smoothly soldering each seam.

Perimeter Foils

Foil pulling away from the glass on perimeter

If this is happening to you, there are several things to remember.

Clean all the edges and surfaces just before foiling. This ensures there are no oils to interfere with the contact adhesive of the foil. Avoid hand creams just before foiling as this increases the amount of oils getting onto the glass.

Remember that lots of heat breaks down the adhesive. So do not remain in one place too long. However the adhesive is not the element that keeps the foil attached to the glass in the long term. Instead, think about whether the bead on the edge is thick enough to provide the rigidity required without relying on the adhesive of the foil.

Finally, think about whether an edging came would provide better support and finish to the piece.

Soldering Copper Foil

Tip sizeSoldering copper foil is ideally done with a smaller tip than for leaded glass. A 3/16" long taper tip is useful. Use the tip on edge rather than the flat side in order to minimize the iron's contact with the glass. Thus, the iron is held almost vertical. Foil heats up very fast and too much heat can crack the glass so the narrower the iron contact is the lower the risk.

Solder applicationThe solder is applied in one of two ways. The quickest method is to feed solder in on the thicker part of the shiny tip and let it flow down to the foil. The iron is held firmly against the foil and pulled along the foil (which has been fluxed) at the proper rate with the solder being fed at the correct rate in order to produce a slightly rounded, shiny solder bead. Don't try and "float" the iron on top of the solder, be firmly down against the foil. This requires practice to match the speed of movement and the amount of solder fed to the iron.

Alternatively, you can do the Bunny-Hop method. This is easier to control and is done by soldering one tip-length, lifting the iron and soldering the next tip-length, barely re-heating the section just soldered. A variation on this is to place blobs of solder at regular intervals along the foiled and fluxed joint and then move the iron along the joint melting the blobs as you go. This avoids the tide marks at the cooling ends of the solder bead.

Tinning brass

Brass transmits heat much more quickly than lead, so a considerable length or the whole of the piece, e.g., a vase cap needs to be heated to avoid the cap acting as a heat sink and so not allowing even tinning of the object.

When tinning any brass pieces, like a lamp cap, rub it with fine grade steel wool (often labeled 000) until bright, then wash the residue off and dry. Apply flux with a fresh flux brush, and hold the piece with a pair of pliers.  Brass transmits heat much faster than lead or solder, so this is a precaution against getting burnt.

At this point you can heat the brass or vase cap with a low heat blow torch to warm the whole piece. When warm, turn off the blow torch and begin applying the solder with the soldering iron.  Touch the piece with your hot soldering iron, pause and then start moving the iron slowly and smoothly over where you have applied the flux, applying a little solder all the time.

Alternatively you can work without the blow torch. Apply a bit of solder to the tip of the iron. Touch the piece with your hot soldering iron, let the piece heat up a little, and then start moving the iron slowly and smoothly over where you have applied the flux.

When the whole piece has been covered, wash it, dry, and then inspect for any missed spots or unsightly solder blobs. Apply a little bit more flux and touch with your soldering iron. If you are doing a lot of this kind of work, an 800 degree iron tip will speed up your work.

Suncatcher Edges

When finishing soldering on a suncatcher, coat the edges with flux, tin the upper edge with solder, repeat on the other side, then flux and tin the outer flat edges, with 60/40 solder. Then hold the suncatcher with a pair of pliers, in a vertical position, and begin to apply the solder in small amounts along the top edge, moving the piece around so the top edge that is level changes. Then go back and connect the little blobs with more solder.

Building up the edge of suncatchers helps the foil from being ripped off accidentally, or just peeling back on its own from being damaged during the cleaning process. This will also allow you to bury a length of fine wire (20 gauge or 22 gauge) around the outer edge of the suncatcher. This provides reinforcement, especially if the suncatcher has a design that has a part of it sticking out on its own, unsupported by the main body of the piece.

Copper Foil Splits

Copper foil splits often occur at tight inside curves. This is caused by the inability of the copper to stretch enough at the edges to make it around in tact.

There are at least two ways to deal with copper foil splits: avoid them or repair them.

Avoidance
One way to avoid splits at tight inside curves is to hand foil pieces that have these curves. When folding the foil from the edge to the sides of the glass, gently and progressively ease the foil toward the sides of the glass with your fingers rather than a hard tool. Do not try to make the fold all at once. Give the foil the chance to stretch into the curve through gentle persuasion.

Another way to avoid the splits is to use several short strips of foil at the tight inside curve. Apply each strip from one side around the edge to the other side of the glass. Overlap each strip until the inside curve is covered. Then you can cover the whole curve in the normal way with the copper foil. When the piece is foiled, you can then take a craft knife and trim the overlapped foils to match the edge of the long strip of foil. Or you can just trim the overlapped foil pieces to match the rest of the foil. Be aware that this increases the space required between the glass pieces as the foil is now effectively twice the thickness of regularly applied foil.

Repair

To repair splits in the foil at tight inside curves that have been foiled along with the rest of the piece, you take small pieces of foil and overlap at the splits.

Then trim the overlaps to match the line of the main foil. You can do this only on the surfaces or by going from one surface around the edge to the other surface.

When tinning these repairs, you need to take care that the heat from the iron does not loosen the adhesive so much that the foil pieces move.

Copper Foil Adhesive

The only technical purpose the adhesive on copper foil serves is to hold the foil on the glass until it is soldered. It is not intended to, and will not hold the piece together. You shouldn't ever rely on it to hold the pieces together. The heat from the soldering breaks down the adhesive, as well as time and chemicals like glass cleaner and flux. If you think that burnishing it harder will seal it, you are mistaken.If your foil is pulling away from an edge, you need to build up the solder on the edge, add wire if necessary, or a perimeter metal of some sort.

If you have a piece of glass that is "slipping" out, you may be trying to hold up too much weight by the foil. Put a perimeter metal on and hang the piece from a solder joint that extends into the design.

Soldering Copper Foil

Tip size
Soldering copper foil is ideally done with a smaller tip than for leaded glass. A 3/16" long taper tip is useful. Use the tip on edge rather than the flat side in order to minimize the iron's contact with the glass. Thus, the iron is held almost vertical. Foil heats up very fast and too much heat can crack the glass so the narrower the iron contact is the lower the risk.

Solder application
The solder is applied in one of two ways. The quickest method is to feed solder in on the thicker part of the shiny tip and let it flow down to the foil. The iron is held against the foil and pulled along the foil (which has been fluxed) at the rate that allows the solder being fed to the iron to produce a slightly rounded, shiny solder bead. Don't try and "float" the iron on top of the solder, be firmly down against the foil. This requires practice to match the speed of movement and the amount of solder fed to the iron.

Alternatively, you can do the patting method. This is easier to control and is done by soldering one tip-length, lifting the iron and soldering the next tip-length, barely re-heating the section just soldered.

Another variation is to place blobs of solder at regular intervals along the foiled and fluxed joint and then move the iron along the joint melting the blobs as you go. This avoids the tide marks at the cooling ends of the solder bead.

Smooth Solder Beads

Good smooth soldering occurs when the temperature of the iron is correct for the job and the solder being used.

The problem of bunched up solder or peaks as you lift the iron from the solder is caused by the iron being slightly too cool for the job and the solder being used. Looking at the conditions causing the problems may lead to a better solution.

If the problem is caused by the iron being slightly too cool to let the solder flow properly, this can be caused by a number of things.

• If your iron is too low power, you may start out well and have the problem develop as you solder.
• If your iron is high enough power and you're using a 'rheostat' or dimmer controller, this has the effect of lowering the iron's power and the problem will occur as above.
• 50/50 (tin/lead) solder requires a hotter iron than 60/40 (tin/lead) solder to keep the molten metal flowing properly.

The best possible soldering iron controller is a genuine temperature controlled iron, where the iron’s controller maintains the tip temperature by applying full power to the heater when the tip cools slightly, but otherwise just 'idles'. If you can't get (or afford) one of these, possibly the best would be to get a higher power iron or throw away the 'rheostat' or dimmer 'controller'.

If the problem still occurs, then use 60/40 solder – which melts and solidifies in a narrower range than 50/50 - or perhaps do the soldering in shorter 'bursts', letting the iron recover for a couple of minutes before starting again.

In any case you need to match the speed of movement and the speed of feeding the solder to the iron according to the capability of the iron to adequately melt the solder.

Also you have to ensure that the foil has been properly fluxed and tinned.

Foil Pulling Away from Edges

If foil is pulling away from the glass on the perimeter of pieces, there are several things to remember.

Clean all the edges and surfaces just before foiling. This ensures there are no oils to interfere with the contact adhesive of the foil.

Avoid hand creams just before foiling as this increases the amount of oils getting onto the glass.

Remember that lots of heat breaks down the adhesive. So do not remain in one place too long. However the adhesive is not the element that keeps the foil attached to the glass in the long term.

Instead, think about whether the bead on the edge is thick enough to provide the rigidity required without relying on the adhesive of the foil.

Finally, think about whether an edging came would provide better support and finish to the piece.

Copper Foil Limitations

Unsupported windowsWindows without either rebar or internal support via Strongline or re-strip should not measure any more than 610mm in any dimension.

Flat work
It is not advisable to create anything over 1220mm (4 feet) by 1830mm (six feet) for a window installation even with re-inforcing bars. All such large copper foiled windows need an exterior piece of safety glass flush against the stained glass. Alternatively, split the window into smaller panels supported on “T” bar.

ReinforcementsAnything over 610mm square normally requires internal reinforcements with either Strongline and/or restrip. Inserting long strips of either Strongline (copper plated steel) or restrip (thicker strips of copper) in between the copper foiled glass pieces to create a "spine" and then a "grid" of internal support is necessary when dispensing with rebar (horizontal lines of brass, steel, or other stiff metals attached to the panel for structural support).

Polishing Solder lines

Before polishing, clean the solder (see cleaning tips) and apply the patina, if any.

Use a good quality furniture polish or wax. Shake the bottle well if it is a liquid, then apply liberally to a soft cloth, or good quality paper towel, rubbing all over solder. If you have a glass with a deep texture, try to avoid this all over process, as it can be hard sometimes to remove all of the polish afterwards, and it is noticeable when it dries. Alternatively, mask off the glass from the solder.

Immediately after applying the polish, take a clean, dry soft cloth or new paper towel, and begin to gently rub the solder seams. If you are using paper towels, you will need a lot of them, as they tear up quickly. When both sides have been polished, check for any missed spots, especially along the edges of your solder seams. Also check for polish residue in tight corners and along the edge of the solder. An old toothbrush often works to remove it. If you need stiffer bristles, make sure you keep this new toothbrush separate from all the others in the house.

Lampshade Pattern Construction, 3

Cut the finished template into sections (if you are using a 360 degree form)
The masking tape template will need to be cut off the curved form and laid out flat. This is easier to do if you can logically separate the template into smaller sections. To do this you need to find lines running almost vertically from the top to bottom of the template. Mark these separation lines in a different colour. Also label each section.

Remove the template(s) from the form and press it out flat
Take a craft knife or razor blade and trim away excess masking tape from the end cap mark. Do the same for the bottom edge. Carefully remove the excess and throw it away.

Prepare a section of your work surface by sprinkling some talcum powder on it, and onto your hands as well. This will help keep the sticky side of the masking tape from sticking where you don't want it later.

Using the craft knife, slice through the middle of each separation line that you marked in a special colour. Try to stay in the exact middle of the line. Be careful that you do not tear or cause to pull away the underlying masking tape as you cut through the line. Do this with each separation line.

Starting with the top edge, use the craft knife to gently pull the masking tape template off the form. If the masking tape starts to separate, stop and repair it. As each section is taken off the form, put it sticky side down into the talcum powder and press it flat. Do this for each section.

Scan/copy the template(s)
At this stage you can scan each section into Glass Eye or other image software. This allows you to:

• select and change colour/glass choices very easily
• print out or email colour proofs to the client
• keep them in an electronic form for future reference or manipulation

You don't have to scan your pattern, but you do need to make at least two copies of the pattern.

Cut out one copy and reapply it back to the form
One copy is fastened back onto the form so that you know where to put your glass pieces.

Cut out the other copy and paste it onto your glass
The other copy is cut out using pattern shears (the three-bladed scissors) and glued onto the glass for cutting.


Based on work by Christie A. Wood, Art Glass Ensembles