Stained Glass Whiz
How to reinforce a stained glass window is something that anyone working with stained glass needs to learn. To prevent bowing and sagging over the years, windows that exceed 4 square feet in total dimension need to have as much stability as possible. When a window is less than 4 square feet, the need to stabilize will depend on the design and where the window is going to be installed.
The constant opening and closing of a door will make a stained glass window bow if it isn't properly stabilized. Therefore, any window, no matter what size, that is going in a door, including cupboards, needs to be reinforced. The same goes for a window that is installed as an exterior window and is exposed to the outside elements, especially wind, or near a door that is opened and closed frequently.
To determine the square footage of a pattern or window, multiply the width times the height, in inches, then divide by 144. To convert metric to square feet, multiply width by height in centimeters, then divide by 930.25.
When I say "depends on the design", I'm talking about straight lines that make hinge joints. A hinge joint is a straight or fairly straight line that allows the window to fold in half. You will often find those straight lines in geometric designs, but they can appear in any design. If the lines doesn't go all the way across the window, it might go far enough that it could not only fold, but break any glass that gets in it's way. The folding can occur at any time the window isn't laying flat on the work surface. It's not fun seeing your just finished window fold in half, pulling the glass out of the lead or foil and perhaps breaking some glass in the process.
So what can you use to reinforce stained glass windows? It's called copper restrip and it works with both copper foil and lead. Copper restrip is made by several manufacturers. Cascade Metals and Venture are the 2 that I'm aware of. I have always used Cascade Metal's restrip, only because it is what is available where I buy my supplies. I have been using it for 20%2B years.
Restrip will bend and follow curves easily as you are using it, but it does not bend on edge. In other words, hold a piece in your hands with the edge facing up and try to bend it by moving both hands inwards (almost the same motion you use when you're breaking out glass by hand). It won't budge. If you hold it with the flat surface facing up, you can bend it with ease.
When using restrip to for reinforcement, it is important to remember that it must run from one edge of the window to the other. That is the only way it will do any good. It can go either horizontal or vertical, or both if it's needed. When it goes both ways, one of the pieces of restrip will need to be cut where it intersects with the other. Then it will restart on the other side of the intersection. In other words, the 2 pieces
will form a cross (%2B) where they meet. Once the panel is soldered, the horizontal and vertical pieces will be joined together from the solder that runs through the lead joint or copper foil seam. There is nothing special you'll have to do to make that happen. It's a natural occurrence that happens when you solder.
Restrip can be used in both copper foil and lead work. With foil, the strip sits on edge between the foiled glass pieces. The glass will need to be cut a little bit smaller to accommodate for the thickness of the restrip. Restrip is about as thick as copper foil with the backing in place. If you will be using a lead or zinc border, follow the directions below for lead.
With lead, the restrip sits on edge, in the channel of the lead. Make sure it goes all the way from one outside edge to the other outside edge of the panel, with perhaps 1/8 inch sticking out beyond each edge. Bend the part that sticks out, up or down, so it lays flat against the outside edge of the glass. That will help the restrip adhere to the inside of the border lead once it's soldered. The principles are the same for using restrip regardless of whether you're working with copper foil or lead.
Copper restrip to reinforce stained glass windows can be purchased at most stained glass suppliers.