I have several 2.5v and 10v rusty,dirty, and rattling UTC small can S series filament transformers that I want rebuild and would like to know a source for transformer varnish and potting material, wax,tar, or whatever. On pulling the cover off the most rattling around one I found only sections of corrugated cardboard to be the "packing/potting" material !!.
Those were the "cheapies" made by UTC. Their higher quality transformers were potted with tar. Some of the older S series actually had louvres in the case for ventilation. These were essentially open frame transformers with a protective case against physical abuse. Later S series did use potting material. These were the lowest quality transformers UTC made, and their ratings are for intermittent amateur service.
Don k4kyv
