Copper foil – to grind or not?

 

This is a question which always has two entrenched sides.  One for always doing it; one for grinding only when necessary for shape.

Some facts:

• The glue on foil is an impact adhesive.

• Impact adhesives stick most securely to smooth surfaces, and resins stick well to roughened surfaces.

• The adhesive is severely weakened by the heat of soldering.

It is a misconception that the adhesive on the back of copper foil tape is a structural element of panels. The adhesive is a temporary means of fixing the foil in place. The heat of soldering seriously degrades the adhesive. 

Therefore, the adhesive can only be a temporary measure to hold the foil in place while the came-like solder structure is created.

The structural element of copper foil panels is in the fin of solder connecting the beads on each side. This forms a came made of solder instead of lead. To be sound, there needs to be a domed bead of solder on each side with solder connecting them.

It doesn't matter in the long term whether the foil sticks well to the glass or not. Yes, it is easier to work if it does stick, but the strength remains in the came formed of solder.

Not every score and break is perfect, and often grinding is required to fit the pieces together. But when the score is exactly what is needed, there is no reason to grind it. The adhesive will stick better to the smooth than the roughened surface.

My conclusion is that it does not matter which side of the grinding issue you support. But why go to extra effort of grinding when there is no noticeable effect in the end? 

It is the came that is created by the fin of solder joining the beads on each side that provides the strength in copper foil panels.

When to Apply Patina?

 Is patina able to be applied days later or does it need to be applied immediately?

The best method is to clean the solder with non-metallic mild abrasives. If the bare solder is left for a while, the solder needs to be cleaned again, as oxidisation begins immediately. Any oxidisation inhibits the patina reaction and provides an uneven finish.

Once the solder has been cleaned with non-metallic scrubbing, wash in cold water, dry at once, and immediately apply the patina.

Can you leave the solder silver with polish/wax until you decide which color and go back later? 

It may be possible, but it is not a complete protection against oxidisation. It will, of course, reduce the amount of oxidisation and make the clean up a little easier. But, any polish needs to be thoroughly cleaned off and the solder scrubbed clean, washed, and dried before applying patina. So it may be most simple to cover the soldered panel with plastic cling film (Saran wrap?), or in a sealed plastic bag until it is time to clean the solder and patina.

In both cases the important elements are to

• clean back to bare solder,

• clean with water,

• dry immediately and

• apply the patina acid right away.

Health Risks from Lead/Tin Solder

"Lead solder – is an open window or an open door in my greenhouse studio required, and in either case do I need some sort of extractor device."

The fumes are not from the lead or solder, they are from the flux.  Eye protection is important.  Gentle ventilation is sufficient.  A small fan to create a current of air to the outside will do of there is no other ventilation.

“If you give items away/sell them. What safety advice do you give to people.”

Lead is only dangerous if consumed.  It is not absorbed through the skin, only by transfer from the skin to the mouth.   Once the piece is handled, wash hands before eating, drinking or touching eyes.

“Is lead free solder a better option for small sculptures, which are not jewellery.”

The risks of lead poisoning are greatly exaggerated. If the pieces are not worn, the risks are minimal. If the pieces are not handled, there should be no transfer to the digestive system. Lead free solder is more difficult to work than a lead/tin alloy.

“What gloves are good to prevent cuts. I’m presuming disposable gloves are best for soldering.”

Skin tight cut resistant gloves are best, but are uncomfortable for long use periods. They can be used for soldering too. Honestly, I don’t use gloves for anything, and my blood lead levels have been below the minimum for the 30 years I have been working with lead and solder.

These are my opinons, of course.

The best guidance on health and safety for stained glass workers, is Greg Rawls’ website.  His career was in industrial health and safety until retirement a couple of years ago. He gives sensible, scientifically researched advice, which is not alarmist.

Metal Rods for Strength

I want to stick a steel rod inside the channel of the H section of lead came. Super glue doesn't work long term, any ideas what glue to use?

Some people advocate wrapping the rod with copper foil and use that as a base to solder the foil to the lead came. This relies on the strength of the adhesive just as super glue does. It will fail in the long term.

There is a method suggested by Gene Mallard years ago that I have used successfully. It encases the rod within two overlapping “H” cames and does not rely on glues at all. It is illustrated here:

Finishing Copper foil Projects

What order do you clean/wax/patina?

A question with many answers.

Almost everyone agrees that cleaning all flux and oil residues are the first stage of finishing. Once the panel is rinsed and dry the stage is set for the finish. The solder is then cleaned of any oxidisation by using steel wool, brass wire brush or some other mild abrasive.

However the industry does not use any metal in the cleaning of any surface to be patinated. Never use abrasive or corrosive materials to clean solder lines holding glass.  The most aggressive cleaner used is that intended for fibreglass baths. Do not use metal or scouring pads when cleaning.

Again opinion differs on the order of processes:

Some wax the solder lines and polish before applying patina.

Some apply patina and wax afterwards.

Both claim success with their method.

Comments from industry indicate that the order is:

Clean

Patina

Protect

Fluxed Foil

 If you take a breaks from soldering do you need to clean it right away or is flux okay to sit? 

Fluxes are mild acids. If left a long time, they will corrode the copper foil – not enough to damage it, but enough that the solder will not take to the foil as it should.   A long time is measured in days rather than hours.

If the flux has been left overnight, it probably will be OK.  The test is whether the solder flows as it did before the interruption.  If it does not, then the flux needs to be cleaned off the foil, and the foil polished with steel wool before re-fluxing.

Liquid flux needs to be used before it dries to be active.  Any interruption which will be long enough to allow the flux to become dry will mean a clean up of the surface is necessary before leaving the piece for a day or more.

Soldering Interruptions

Do you have to finish soldering/cleaning all in one go? 

Interruptions in soldering are possible, but they should not be long. The flux is an acid and will affect the copper foil. The acid although mild, will began to cause enough corrosion to make further soldering difficult after a few days or a week. If the recommenced soldering is not working as previously, the flux needs to be cleaned off and the oxidisation layer removed from the foil. The easiest way is to use fine steel wool and carefully polish the foil with it. Then flux the area you think you can accomplish in the time you have.

If there is likely to be a significant time before soldering can begin again, clean off the flux and finish with a neutralising compound, or a solution of baking soda. Dry and cover with a plastic sheet, or if small enough, put it into a sealable plastic bag.

If it is a big job in relation to the time available, only flux what can be achieved in that time. This saves clean up time. Although it may be necessary to polish a thin layer of corrosion from the foil before resuming the soldering.