Originally Posted by
Steel Charlie
Linseed oil (BLO) is nothing more than the basis for most varnishes. That is effectively paint without color. You'd be better off just using about any varnish cut 50/50 with thinner cos BLO alone is crap on every level
I'm not trying to argue here, just clarify.
It is my understanding that BLO is similar to the base for oil-based paints. BLO may keep liquid water off the surface but does little to impede water vapor from reaching the steel.
Varnish is different than paint and does not come from BLO or linseed oil. Certainly, modern polyurethane varnishes are man-made and not based on BLO. I'm going to Wikipedia to research varnishes.
Shellac is different yet again. I really like shellac but it may be too brittle for use on a bike.
droppedandlost - a clear coat could help prevent rust. Clear coats can be matte (do not have to be "shiny"). If you are trying to create a rat rod or steam punk look with a modicum of practicality, look into that.