The Making of the Glencairn Methuselah Window: Page 41

Tracing about half Mediaeval Red, Half Mediaeval Black – by sight mixed with thicker oxidized turpentine thinned then with ordinary turpentine and then thinner oxidized turpentine added.

The above dried one night

<fig.12, front view end of brush left of this paragraph> Took 30 day oxidized turpentine and mixed it with Backing – then added still thnner oxidized turpentine – and after the glass for the hand HAD BEEN HEATED on stove, coated with a Japanese soft haired square ended brush the above mixture over the tracing – not too heavy. (It appears when fired about as it does when real wet)

Now I mixed ordinary thin turpentine with the above mixture and dropped this onto the film just described where it made little circles – where the flat film occurred I went over the top of the first film and put Backing on thicker.
Back – mixed backing with thicker oxidized turpentine with thick clots then added turpentine, thinner oxidized turpentine diluted with a lot of thin turpentine. Continued