I was told at a tile store (disclaimer: I was told something at a lighting store that turned out not to be very accurate) that to get the crackle finish, after the tiles are baked, a thin glass layer is added to the surface, heated at a high temp, then cooled quickly creating "cracks" in the glass, hence the "crackle" finish, and that it should be sealed. I do believe it should be sealed, as I had a sample of one where something had permeated a portion of the crackle surface, and it didn't appear there would be any way to clean it at that point.

thank you, did you end up buying the crackled tiles? I am assuming I will be able to seal the ceramic knobs with the same product as the tiles...

Very interested in the answer to this, as we are considering a crackled subway BS.

Can anyone with a crackled tile backsplash share whether they have had any difficulty keeping the "crackled" surface clean?

I would love the answer to this question as well.

We used crazed tile in our bathroom, and while the bulk of it has held up well and has had no cleaning issues, the tile in the shower is a mess. Soap, mildew etc. has gotten in the crazing and it is impossible to get out. I'm certain the tile was not sealed properly by the installer, but it's made me hesitate to use it as a backsplash tile (and certainly won't use it again when we redo the shower). Would love to know whether grease gets in the cracks, if used behind a stove.

No, we didn't end up with crackle tile. I decided I wanted harlequin (which means diamond/trapezoid shape) tile. It tends to be very expensive, but our local tile place found a discontinued batch of handmade dove glossy from Astor tileworks for less than 1/2 price, so we bought that.