The Making of the Glencairn Methuselah Window: Page 34
Tracing and half tone films.
Mix paint until mass is well saturated with the thicker oxidized turpentine
– but mass not shiny – a dull gloss or drysish – dilute with a little ordinary thin turpentine, then add 30 day oxidized turpentine, then add 30 day oxidized turpentine. If paint gets too oily add more dry paint.
Used No. 1 tracing fine French Brushes Drakenfeld & Co. Did
not cut it down with a razor.
Halftone film – 1 part Mediaeval Black and 2 parts Modelling Clay Backing
Use thicker oxidized turpentine until was in dryish clots –
then added, I think it was the thin 30 ay oxidized turpentine. Used
regular tracing brush described above. Drag brush over so to make
delicate film<undecipherable, fig.9 side view brush on glass