One of the main steps in the process of the copper foil technique of stained glass is to actually apply copper foil strips to the outer edges of the glass.
For some people, this comes easily. While for others, it’s a painstaking process of misaligned copper foil needing to be pulled off and re-positioned numerous times, potentially followed by mumbles and grumbles of all sorts. For those who really struggle, it's at this point a concession is made to the fact that the piece of foil that has been giving them grief, is too crumpled or no longer sticky enough to use and therefore discarded... All to begin again.
What does it take to actually get the foil centered on the glass and smooth?
Let's take a step back for a second and discuss the foil first.
Copper foil is placed around all edges of each piece of glass and pressed down along the front and back. Since solder will stick to copper and not to glass, this is a necessary step to allow the assembly of your project in the soldering stage.
I'll go into further details about the types of foil in a future post but for the moment, let's suffice it to say that I generally use a 7/32" (Edco brand) copper foil.
In order to get proper adhesion of the foil to the glass, it is important to clean all of the edges of glass after grinding. This removes any chance of glass dust getting in the way and preventing proper adhesion of the foil to the glass.
Simply washing the glass in warm water with a little bit of dish soap will get everything clean and ready for foiling.
What seems like a simple process of applying copper foil to stained glass can feel a little more daunting than it first appears. Many people get very mixed up in how everything is being held versus whether or not they can see what they’re doing.
The Real Trick is Being Able to See What You're Doing
Now there are foiling aids available in both hand held and table top models but in this article I’m focusing on how to foil completely by hand, which happens to be the current way I tackle all of my projects.
I'm right-handed and I hold the foil in my left hand freeing up my dominant hand to manipulate the glass as needed.
By holding the copper foil with the foil side face down and the adhesive side face up between my index and middles fingers, I can use the thumb on my left hand to to peel the paper backing off the copper foil as needed.
By applying the foil in this fashion, I can see exactly what I'm doing when I'm placing the glass on top of the foil.
Also, try not to handle the adhesive side of the foil too much since the oils in our skin interferes with the adhesion. You'll have to touch it occasionally but try not to be in the habit of putting your fingers all over it, all of the time.
It doesn’t really matter where you start the foil on a given piece of glass, but I personally like to start near a corner if there is one.
It’s important to get the foil centered as this will affect the overall seam width once it’s soldered to the glass piece next to it.
Work your way around the piece applying the foil centered on the glass while avoiding touching the adhesive with your fingers as much as possible.
Once you get back to where you started, the foil should overlap the first end by a quarter of an inch to 1/2 inch maximum. Trim it off using a craft knife or a pair of scissors.
Folding the Foil Over the Edges
Next, the copper foil is crimped down over the front and back edges of the glass.
When it comes to sharp corners, making them tidy creates a cleaner line along the edge of the copper foil as it approaches the corner. Do this by foling one edge down tight into the corner (I use my fingernails to get right up close,) then fold the second edge over the first. This creates nice clean lines at the corners.
Using a burnishing tool, I like to use a fid, the edges of the foil are rubbed smooth so that the foil presses down flat to the glass and all of the little crinkles and ridges are removed and the foil is smooth.
How to Remove Copper Foil That's Not Perfectly Centered on the Glass?
Now, when placing the foil, there are times when you'll notice it’s going off center. In these instances, you need to pull the foil back to lift it off the glass and then reposition it. However, if you don't realize that you've gone off center until after you’ve burnished it, then the easiest way to remove burnished foil is to use a craft knife and slice off the front and the back.
Once those are removed, then it’s easy to remove the outside edge by slipping a knife under the foil and pulling it off easily.
With all of the glass pieces prepared with foil, you can move along to soldering your project.