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How to reinforce a stained glass window is something anyone who works with stained glass should learn. To prevent bowing and sagging over the years, windows that exceed 4 square feet in overall dimension should be as stable as possible. When a window is less than 4 square feet, the need to stabilize it will depend on the design and where the window will be installed.
The constant opening and closing of a door will cause a stained glass window to tilt if it is not properly stabilized. Therefore, any window, regardless of size, that enters a door, including cabinets, should be reinforced. The same goes for a window that is installed as an exterior window and is exposed to weather, especially wind, or near a door that is frequently opened and closed.
To determine the square footage of a pattern or window, multiply the width times the height, in inches, then divide by 144. To convert from metric to square feet, multiply the width times the height, in centimeters, then divide by 930.25.
When I say “it 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’ll often find those straight lines in geometric designs, but they can appear in any design. If the lines don’t go all the way through the window, they may go far enough that they will not only fold, but break any glass that gets in their way. Folding can occur any time the window is not lying flat on the work surface. It’s no fun watching your newly finished window bend in half, pulling the glass out of the lead or foil, and maybe breaking some glass in the process.
So what can you use for reinforce stained glass? It’s called a copper restrip and it works with both copper and lead foil. Several manufacturers make the copper strips. Cascade Metals and Venture are the 2 that I know of. I’ve always used Cascade Metal’s replacement tape, just because that’s what’s available where I buy my supplies. I have been using it for 20%2B years.
Restrip will bend and follow curves easily while in use, but will not fold at the edges. In other words, he holds a piece in his hands edge up and tries to bend it by moving both hands inward (almost the same motion he uses when he breaks glass with his hand). He will not budget. If he holds it with the flat surface facing up, he can easily bend it.
When using the strip for reinforcement, it is important to remember that it must run from one edge of the window to the other. That’s the only way it will do any good. You can go horizontal or vertical, or both if necessary. When going both ways, one of the pieces of the new strip will need to be cut where it intersects the other. It will then restart on the other side of the intersection. In other words, the 2 pieces
they will form a cross (%2B) where they meet. Once the panel is soldered, the horizontal and vertical pieces will be joined with the solder going through the lead joint or copper foil seam. There is nothing special you have to do to make that happen. It is a natural fact that occurs when you weld.
Restrip can be used on both copper sheet and lead work. With foil, the strip sits on the edge between the foiled glass pieces. The glass will need to be cut slightly smaller to accommodate the thickness of the strip. Restrip is as thick as copper sheet with the backing in place. If you are going to use a lead or zinc trim, follow the instructions below for lead.
With lead, the strip sits on the edge, in the lead channel. Make sure it goes from one outside edge to the other outside edge of the panel, with maybe 1/8 inch sticking out past each edge. Bend the part that sticks out, up or down, so it is flat against the outside edge of the glass. This will help the new strip stick to the inside of the rim wire once it’s soldered. The principles are the same for the use of adhesive tapes regardless of whether you are working with copper or lead foil.
Copper restraint for reinforcing stained glass can be purchased from most stained glass suppliers.
