A Varnish for Fixing Smoked Tracings

Abstract

IN damp weather it has been noticed that a good many varnishes produce a white precipitate when used for fixing smoked tracings after experimental physiology work. This naturally interferes with the final tracing and sometimes forms all over it, thereby obliterating the original work. We have prepared a great number of varnishes, and of them the following has been satisfactory. A white haze does form even with this varnish in a moist atmosphere, but it disappears on drying. The following is the formula for the varnish: gum juniper, 60 gm. ; colophony resin, 13gm. ; castor oil, 5 mil. ; industrial methylated spirits, 200 mil. This produces a glossy finish, ideal for demonstration purposes and even class work.