Foil and Solder / Every pattern
Measuring the opening
Measure where the glass sits, not what you see.
Windows and transoms
The glass sits in a rabbet behind the stops. Pull one stop or measure from the back, side to side and top to bottom, at three places each way, and use the smallest number. Take off 1/8 in each way so the panel drops in without forcing.
A panel over an existing window
If the panel hangs or mounts inside the window frame in front of the existing glass, measure the inside of the frame where it will sit and take off 1/4 in each way.
Sidelights
Most sidelights are double-glazed units; the panel goes in front of the glass or replaces it as part of a new insulated unit made by a glass shop. Measure the visible opening inside the stops.
Cabinet doors
Measure the opening at the back of the door frame, where the glass sits in its rabbet, and take off 1/16 in each way. Panels for cabinet doors are usually framed in thin zinc or brass came.
Half-round transoms
Measure the width at the bottom, inside the frame, and the height from the bottom to the top of the arch. A true half-round is half as tall as it is wide.