How flat should a tile be?

[kevd]

About a year ago I bought some Porcelanosa Marmi Blanco 600x300 rectified tiles to put up in my ensuite, but due to a couple of reasons I was unable to fit them at the time.

Now, I am getting geared up to fit them and I though I would give them a check over. It seems that when I look down the long edge, the tiles have a mild hump in them - i.e. they have cupped ever so slightly. If I put a straight edge on the glazed side, the 2 ends of the tile are slightly off the surface - and when pressing the straight edge on say the left side, then after 600mm the other edge is probably just under 1mm off the straight edge!

They have been stored flat (boxes stacked on top of each other, which have been layed on a flat floor) in my garage all the time .

Should these tiles be 100% flat or is some minor cupping normal on any tile? My concern is that I am planning on putting these up with a small (2mm) grout gap and as they are rectified tiles any uneveness is going to stand out a mile.

Should I call them to complain or ??

Any help would be greatly appreciated. I cannot afford to buy a new load of these as they were not cheap and I have had a year of redundancies (twice)!

 

[kevd]

Just spoke to Porcelanosa and they say that for large tiles such as these (600 mm long x 300mm) then a small amount of bowing is normal (minor) but that they don't recommend laying large tiles in a brick bond as this would then be noticeable.

Which I can understand.

So, is this really the case or am I being fobbed off a little!

I brings back memories of my dad whose kitchen tiles, after being in a garage for years, all bowed. Apparently due to the glazed side being non porus but the ceramic side being exposed to moisture, therefore over time they bend!

Mine are very minor, but I would like to check before putting them all up and having a problem.

 

[markfxy]

This is normal marble or granite will be flat but ceramic tiles of this size will have a slight bow in them