If you are planning on making alcohol ink painted tiles, here is my take on the varnishes.
First, the worst.
This varnish completely ruined a set of tiles. I bought it hoping that the smell of tolulene and xylene would be reduced when I sprayed the tile. I never expected it to lift the inks off the tile and flake them off. Here's the result of using this spray varnish. You can clearly see flaking of the crystallized ink. Do NOT use this varnish to seal your tiles.
The second varnish is the Triple Thick Crystal Clear Glaze.
It isn't as bad as the Low Odor Varnish, but still not great. It gives a really nice glazed look, thick and clear as a baked finish, but it blurs fins lines. As you can see in the top picture, the circles have thick lines around them, those lines were thin as if drawn with a ballpoint pen and after spraying, they look as if they were drawn with a fat marker. If you want the high gloss look, use this spray, but if you have any fine lines you want to retain, this varnish will not do that.
I use the Krylon Kamar Varnish.
It is made for art, so it's gentle on the inks. It takes a few coats and the finished product doesn't have that glass clear finish, but the results are great. It retains the fine lines and there is no flaking or damage to the ink surface.
Bottom line...
Low Odor - No redeeming qualities, ruins your image entirely: Thumbs down, huge NO
Triple Thick - Okay if you want a high gloss finish and don't have any fine lines: Neutral
Kamar - Not as high gloss, but retains the painting of fine lines: Thumbs up