How do I go about sealing tiles painted with acrylic ink? I have been painting on ceramic tile's with Liquitex acrylic ink. I would like to seal them so that they could be used as coasters. I want to make them impervious to liquid and coffee cup heat. Does anyone have suggestions on sealing the tile's? When I sprayed some Krylon UV clear protector, the ink was reactivated and began to spread. I was thinking of putting some Liquitex gloss medium on the tiles and thin coating them with clear water-based polyurethane. My other alternative was to use art resin but I'm unclear which would be the best way to go.
Both methods should work; polyurethane varnish seems to be a fairly standard way of sealing acrylic paint on ceramic (see this thread on potters.org for example) and Art Resin* claims that 'the heat generated from a hot mug will not damage the resin surface' and that it is suitable for use on ceramics (ArtResin FAQ, points 24 and 25).

I also stumbled across some people saying that you can bake acrylics in the same way that you can enamels - no guarantees, but you might find that this works for you.

However, given that you've already had some issues with the ink dissolving in the varnish(possibly caused by attempting to varnish before the ink was fully dry) I suggest that you test your chosen method on something disposable before you seal your coasters.

*a brand, but the same points should apply to most clear two part epoxy resins