When Copper Foil Won’t Stick To Your Stained Glass

applying copper foil to stained glass

Have you ever experienced this situation? Where ​no matter what you do, the copper foil won’t stick to your stained glass​? 

It’s a common ​occurrence. I’ve even had this happen numerous times over the years.

So how do you deal with it? 

In this post, ​I explain what ​to consider when problem-solving this issue. 

applying copper foil to stained glass

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​Why does the copper foil not stick when applying it to stained glass?

There are generally 4 reasons that this will happen:

  1. The glass is dusty or oily which prevents proper adhesion of the foil.
  2. Your fingers are all over the foil when applying it.
  3. The foil might be old or it’s just a bad batch. (I’ll let you in on my favourite, most reliable one too!)
  4. The project was cut and ground a long time ago and you’re just now getting around to foiling it.

Let’s start at the beginning, ok?

​How ​to clean the glass

Once you’ve cut and ground your stained glass pieces, ​the glass​ must be clean before the foil will stick well.

I’ve seen amazing ​stories on ​social media ​of what steps some people go through to clean their glass​. ​I have to admit that it leaves me ​stunned. The lengths that people go through to ensure good​ adhesion for every project is staggering. 

​When using a good brand of foil, you shouldn’t have to move mountains to make it stick! Let’s keep it simple. 

When your dishes are dirty, what do you do? You fill a sink or basin with hot water and soap. Then, using a dish cloth or sponge​, you wash your dishes. ​When washed properly, they’re clean enough to eat off of, right? That's the goal. They're clean.

​Why should stained glass preparation for foil be any harder?

Some ​say that you need to scrub the glass with all sorts of cleaning products. Others say to ​use them in a certain order to ensure proper adhesion of the foil.

But, ​washed properly with soap and water, and dried thoroughly, you​ won't have to partake in time wasting rituals to get the job done. It’s not like you have to dance around under the full moon juggling 5 apples, of which 3 must be green and 2 must be red, to make it work. I promise!

Just stick with washing it well with dish-soap (any brand will do) and water. Rinse it really well and ensure it’s completely dry before trying to stick the foil on, ok?

Good!

Keep your fingers off the adhesive side of the foil

Do you touch the sticky side of the foil with your fingers while you’re positioning it along the edges of the glass? If you do, you might be causing the issue.

Our skin has natural oils in it and by touching the sticky side of the foil repeatedly, you’re transferring that oil to the adhesive. This interferes with the foils ability to stick to the glass.

In step one we made sure that the glass was clean and there was no oily residue left from our cutters. Now, we need to keep our fingers off the back of foil.

Touching it once or twice is fine, but the constant handling of the adhesive will damage its’ effectiveness.

​The problem is with the copper foil itself

I have tried various types of copper foil and now only use Edco (except if I’m using the fancy scalloped new wave foil.) Edco foil sticks super well and it’s soft enough yet thick enough, to allow easy placement and stretching along most shapes, even tough inside curves. 

When applied carefully and with thought in how to lay it all down along deep inside curves, this foil can almost stretch or elongate to lay flat without those nasty little cracks that have to be patched. Plus, it sticks really well!

If you got a lemon, which obviously could happen with foils from time to time, I suggest cutting off a few feet from the roll and try again. I have seen over the years that occasionally (I think I’ve had this happen to me twice over the years) that something happened to the adhesive in a couple of small sections along the roll. To me, it appeared to be something that happened during manufacturing.

Sometimes it will feel as though the thickness of the foil changes or the tackiness of the adhesive is suddenly different. That is obviously a problem with the foil. 

Stick with the foils you know and trust.

This is part of the reason that I stick with Edco

The age of the foil can also make a difference. If it’s been kicking around for 10 years and you notice that it isn’t very sticky at all, it’s probably dried out. Toss it, and get yourself a new roll.

It is also recommended that foil be stored in airtight spaces like a zip-sealed bag. This will certainly extend the life of the adhesive, but in my own studio I’ve left some out for about 6 months and they’ve been fine. I suppose it depends a bit on the climate where you live, but my studio is kept fairly low in humidity year round.

question

​Did You Know?

The adhesive holds the copper foil in place on the glass but it’s really not the adhesive that holds your project together?


Back before adhesive backed foil was brought to market, plain copper sheets were used instead. Sheets without any adhesive, were cut into strips and placed around the edges of the glass.


But this won’t hold, you say? Well, if done properly, it ​would. You see, the copper is strictly a foundation for the solder to be placed on top of. 


With the solder built up enough, it creates a solid metal channel which hold the glass in place. The adhesive backed foil in long rolls is really just a convenience for us. Not a necessity for making stained glass!

​You cut and ground the glass a while ago ​

Lastly, if the glass is clean and the copper foil is good, what else could prevent the foil from sticking well?

In my experience and for those I’ve passed this tip along to agree, the length of time since cutting and grinding the glass to when you’re applying foil, seems to make a difference. 

Now you might think I’m a little off my rocker for what I’m about to say, and I don’t know if there is any scientific explanation or not, as I’m not a scientist and I’ve never researched it. But, in practice, it would seem the edges of the glass are picking up impurities from the air and holding them like a sponge. 

I know, crazy right? Glass, like a sponge? 

Laugh all you want, but in practice I’ve dealt with this many times. And,​ when you observe things closely enough, you start to figure out ways of dealing with these odd problems. 

This often leads to unusual concepts helping us relate these ideas to something we can understand and make sense of. At least in my imaginative mind it does!

​Does glass pick up impurities like a sponge?

​With a project that was cut, ground and cleaned 6 months ago and stored on an open tray​ is taken out in the present day to be worked on, you’ll probably wash it again. But when you try to apply foil to the dried pieces of glass, it won’t stick. And yet, you know the foil is perfectly good as you just finished another project without any issues at all.

So we’ve gone through the problem-solving of steps 1, 2 and 3 and know that the glass is clean, our fingers aren’t the problem and the foil is good. 

So what’s the problem?

Go ahead and do a light grinding along the edges of the glass even though it was ground to fit perfectly 6 months ago. Just one quick light pass along the grinder, then clean the pieces and dry them before attempting to foil again. 

Now foil...

Lo and behold, you’ll find that the copper foil sticks! Exactly as it should. 

And the only thing you changed, was ​removing the very outer layer of the edge of the piece of glass by grinding it.

Magic? Maybe. 

Was the glass acting like a sponge? I don’t know…

But that’s exactly how I think about it. 🙂

How about you? What have been your experiences with foil? Let me know in the comments below.

Leave a Reply 3 comments

Roger - November 7, 2019 Reply

Thanks for the reminder on how not to be fooled by foil.
I have some very old sealed packages of copper foil that I will finally be able to get back to.
The only tip I hope not to have to follow is the toss and replace the foils. Lol

SteveR - November 7, 2019 Reply

I think, though I’m not 100% sure, that copper foil is recyclable. The copper part is, and so is the paper backing, but does the adhesive mean it’s not? It would be nice to find a definitive answer to this, because I have about 5 pounds of old rolls that may need to be tossed. Also, a further hint about getting the foil to stick. The oils on our hands can be very effectively removed, for the duration of a working session, by simply washing a load of dishes in the sink, by hand, without gloves, in fairly hot water. After you’ve done that, your hands will be so oil-free that you can press a fingertip onto a mirror and not leave a print!

Pat Crider - November 11, 2019 Reply

Hi Sam, good read! I did not know about the situation with glass sitting for 6 months and foil not sticking. Amazing. I was a little surprised that you did not mention the issue with going over the foil too much with the soldering iron. Or is that really an issue? Thank you for the information. I have a feeling my current piece will turn out better.

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