QUESTION

Long stone tiles often bend during manufacture but is it possible for a 150mm x 800mm stone tile to bend due to improper storage? My stone tiles seems to bend at their ends.

ANSWER

ANSWER - I am assuming that when you say stone tiles, you mean natural stone cut into tile shapes.  When you say the tile bends, I am assuming you mean that it warps.

Some types of natural stone will tend to warp when they are subjected to moisture and then dries, and when they are subjected to high temperatures and then cool.

When stones are subjected to moisture or heat they expand, and when they dry or cool the contract.   When there is a disproportionate of expansion or contraction, then the stone warps.  For example, if the bottom side of a stone that is sensitive to moisture expands, and the top side is not exposed to moisture and doesn't expand, then the stone warps up if not properly restrained.   Similar to a wet sponge on an impervious countertop.  The top of the sponge dries before the bottom of the sponge, so the top of the sponge contracts, which causes the edges of the sponge to warp up.

So if you store the stone in a way where it is being subjected to disproportionate moisture and temperature cycles, then they can warp.  Once warped the tile cannot fully return to a flat condition.