The first tile test was with water. I dipped the bottoms of glasses in water, set them on the tiles, and left them. For a couple of days, actually, since I forgot them.
When I picked the glass off of the tile, I saw white blurs and my heart sank:
However, I left them alone and the blur went away as the tile dried. I repeated the experiment and left the glass on for about five hours. No blur. I'm not sure what to do. Can I sell them this way? Even if someone leaves a glass on them for days, the blur isn't permanent. But I am still reluctant to sell them because I feel like I have to include this long explanation with them in case this happens to any one.
Or I could try to figure out another way to seal them.
Any way, testing continues with ....
Test Two: Grape Juice