You can coat it in paint, lacquer, varnish etc. because we have had customers do just that. ie. they sprayed it with clear coat of "something". i have read others having done same too so i doubt you will have much issues.
however, i think the ingredient of whatever you put over it "might" come into play due to a chemical reaction. easy solution is do some test mate.
i don’t know what you will be rubbing it down with after the first coat but guessing it will just be something like a flattening paper?