How to Repair Bowed Stained Glass

fabrication d'un vitraille image by RomainQuéré from

Stained glass panels constructed using the lead came technique can bow over time due to the weight of the glass stretching the lead came. Bowing also results from improper support of the panel. Restore the panel by replacing the lead came and adding support bars as needed. Use care not to break any of the glass pieces when taking apart the panel, and make a copy or record of the pattern before taking it apart.

Trace or draw the pattern and colours for each piece on the paper. Number all the pieces and use this as the pattern to rebuild the panel once it is taken apart.

Melt the lead solder that connects the joints of one side of the frame with the soldering iron and pull it carefully away from the panel. Use care not to melt the metal of the frame, which is usually zinc. This can be saved for later use, or replaced if it is not in good shape.

Remove the first row of glass made accessible by taking off the piece of frame and clean the old putty off the glass. Number each piece according to your pattern before removing it. Continue to remove lead came and glass pieces until the bowed section is removed. Sections that are not bowed can be removed whole by melting the solder joints around that section.

Stretch the pieces of new lead came just enough to straighten them out before using them. Clamp one end in the vice and hold the other end with pliers to pull it firmly until it is straight. If you stretch the lead too much the channel becomes too narrow to fit the glass.

Rebuild the panel by cutting new pieces of lead came to fit around the pieces of glass and fitting everything back together according to the pattern. Hold pieces in place using the horseshoe nails.

Brush flux on each joint between the lead came pieces and solder them together on one side of the panel and then the other side.

Put on the latex or nitrile gloves and push putty under the edges of all the lead came with your fingers or the fid or lathekin.

Brush the putty under the lead came on the entire panel with the nylon bristle brush.

Put on the dust mask, place a layer of newspaper under the stained glass panel, and sprinkle whiting powder over the puttied side of the panel.

Scrub the entire panel with the natural bristle brush to push the putty under the lead came and scrub the putty off the top of the lead came and glass.

Run the nail or toothpick along each edge of lead came to remove any little pieces of putty that are sticking out.

Vacuum the putty granules off the stained glass panel with the hose attachment.

Leave the panel to dry for as long as possible. Twenty-four hours is usually sufficient.

Repeat steps 7 through 13 on the other side of the panel.

Clean both sides of the panel, picking any putty off that was missed the first time.

Cut lengths of reinforcing bar to fit the stained glass panel. These bars should fit from the outside edge of one side of the frame to the other along the length of the panel. Place the reinforcing bar along a vertical or horizontal line in the pattern to help hide it.

Mark the solder joints at intervals along the length of the line where the reinforcing bar will be placed.

Cut pieces of wire long enough to wrap around the reinforcing bar and solder them in place on the lead came at the marks.

Wrap the wire around the reinforcing bar and solder it in place at the top and bottom, and at a few places along the seam for further reinforcement.

Clean both sides of the stained glass panel to remove all traces of flux.

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