First I want to give credit to Lee Davis for his helping me with the fundamentals of the reverse glass painting process. His instruction in the process of stencil prep and the painting process as well as study of the product produced by the many artists who painted for these clocks, most anonymously, has been invaluable to me. He has my eternal gratitude for opening up another avenue of this exciting hobby.
The fist step is to select and cut a glass period appropriate for the clock, meaning if the clock had old wavy glass that is whet you should be painting on. I have harvested a number of old windows and repurposed them for clock dial or door glass. for a reverse glass it can had numerous production defects, i.e. bubbles or bumps, as many are hidden in the design.
once you have the glass the proper size you must decide which will be the front or back of glass, this will be determined by the appearance of glass, place best appearing side out. Mark glass with a sharpie pen "FRT" so it will be obvious which side is which. Now I use the sharpie to outline the door frame on the glass, this determines the visible part of glass for centering the design.
The next step after selecting the design is to make a stencil for the border. I will post photos of the stencils made for this design. There are a number of steps involved so ask questions if you wish. The stencil pattern in this case was drawn free hand and then traced to linen drafting paper and cut out with an exacto knife.
There are three stencils to be made: 1) corner 2) top (short strip to be used also for bottom) 3) side (longer one for both sides) the first photo shows my calculations for the length of each stencil the others the different stages of the stencils