Large stained glass panels require support to decrease bowing and breakage caused by the weight of the glass and the lead used to construct them. Traditionally, strips of metal, known as a reinforcing bar (rebar), were installed along the entire length and width of the panel. Copper reinforcing strips are a recent, as of 2010, invention placed between glass pieces before soldering when constructing a large panel using the copper foil method. Provide additional support to stained glass panels with a zinc came or wood frame.
Measure the reinforcing bar to fit the full length and width of the large panel, and cut it to size with a metal saw. Cut the shorter bars where they cross the longer ones. Reinforcing bars are available in steel, brass or zinc.
Brush each bar with flux, and apply a thin layer of solder to the entire length of the bar.
Position the bars in place on the panel, and mark strategic lead lines where wire can be soldered to twist around the bar, providing additional support.
Cut strips of wire, and solder them in place on the marked lead lines, using flux to adhere the solder to the wires.
Set the reinforcing bars in their final positions, and wrap the wire around them to hold them in place.
Brush flux at strategic points along the length of each bar, and solder the reinforcing bars to the window.
Cut pieces of the copper reinforcing strip to fit the length and width of the large panel. Take into account the bends in the pattern that the strip must follow.
Set the strips into place between the pieces of copper-foil wrapped glass. At each intersection, cut one strip so that there is a 1/4-in. overlap in each direction. Bend these pieces in opposite directions along the seam so they don't overlap.
Place weights along the strips as needed to hold them in place.
Brush flux along the seams, and solder the panel together on both sides.
Trim all of the edges sticking out the sides to 1/4-in., bend them along the sides and solder them in place before framing the panel.
Cut the framing material to fit around the outside of the large stained glass panel. Cut the corners either mitred (at an angle) or with straight cuts so they overlap correctly, taking into account the size of the framing material.
Fit the glass into the zinc came frame, brush flux at each corner and solder the frame together. For a wood frame, fit the pieces together, and use screws to fasten them securely. Use C-clamps if needed to keep the pieces at the exact right angle.
Brush flux where each solder line intersects the zinc frame, and solder the frame to the panel. Fit the stained glass panel into the channel cut into the back side of the wood frame, and fasten it in place with silicone or glass clips.
Rebar can be bent to follow the lines of lead in the window and soldered in place to provide support without distracting from the design.