Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Probably best to not try pencil lead on the power piston as it has a very high clay content to make it hard. Better to get a small tube of powdered graphite from the hardware store, generally used to keep keyway tumblers in door locks working smoothly. I generally put just a tiny bit in a bottle cap and make a slurry of it with alcohol, so that I can brush it on the surface and have it stick as an extremely thin film.