varnish on slate floor
(kiln, ms. )
How to remove varnish from a slate floor.
I'm not sure what varnish is made of, maybe some kind of polyurethane.
I don't think it's water based, so you can't use water based strippers.
My guess would be paint strippers. What ever you use, it's not going to be eco-friendly and you will need to dispose of the waste in a environmentally safe place.
This is a a very messy, and in my opinion dangerous job to do, because of the chemicals that need to be used.
This is why I never recommend any coating on natural stone.
I wish I could help, but I don't do any of these types of jobs.
Paint stripper or find a company in your area that can help with this type of finish.