Definitely poly. Better yet--use a marine spar varnish as it is water resistant/water proof.
I am not sure how durable this is going to be for you which is why I suggested the marine spar. I think it will last much much longer this way.
Hi Lisa, you can buy a nice matte clear coat as well, mask off around it and it won't ruin the nice matte look of the chalk paint
I used it on a sign I painted and hung outdoors in elements year round and it has help up fine, rain, snow hail wind, you name it!
I totally agree with marine spar varnish, chalk paint is not designed for wet areas the marine spar varnish will give you the most life out of your countertop.
Lisa: especially on a countertop --- wax would not hold up!
Because of the water present in bathrooms, I'd recommend poly. Several coats.
Best product would be Minwax Helmsman Spar Urethane.
Personally I would only used paint specific for countertops. Should be epoxy based
Hi! Poly will give you more durability. Stay safe!
Spar varnish is the best because it is made to be used near water. That is what the boats are coated with. I do not think a chalk paint counter top will last very long in the bathroom. You may want to try a good epoxy or resin.
I would make sure the Varnish/Finish you use if water proof otherwise you are going to have to keep re-doing it! Maybe Yacht Varnish - Clear!
Hi Lisa, definitely the marine spar varnish, it's designed for use outdoors, so moisture won't be an issue for it!