Thanks. However, from a moisture protectant point of view it would be very good but not sure how it would stand up to heat, as in a hot cup of coffee etc.
Like Ryan said. Marine spar varnish would be a good call. Used it on mine. Not affected by hot coffee cups. They really aren’t that hot. If the cup is glowing red, don’t drink the coffee.
I did a test coaster and no finish - it absorbed moisture got moldy and warped in a week… I have been using an Oak and Purpleheart wine bottle and glass thing that has a spray poly on it and not one problem for about 6 months it was just on the desk and I set my glass on it as a coaster. I am making them with brush on poly now too since the spray is kind of a cheap way of doing it for something that could possibly have liquid on it for extended periods of time. That is my theory but I do not need the guys that do spray poly only freaking out here - I just prefer over doing things and a can is cheaper than a couple of rattle cans any way.
I brushed on a very thin coat of clear lacquer on a set of cherry coasters I made last year. They are used everyday for both hot and cold and I have had no issued with them at all.
There are some very good 2 part resins that can be poured over the finished work. They’re high-gloss, heat resistant and very durable. Most woodworking or specialist paint suppliers will have them.
Could be perfect for coasters.
Cheers guys … that gives me something to work on. Not sure which way I will go but maybe try all of the suggestions and settle on what I think seems to work best.