All large format tiles can have a slight curvature, this is perfectly normal and within industry standards. If you are laying “brick bond” they should not be half bonded but 30% of the length.
Rectified means the tiles have been machined to size following the firing process, however tiles from different production batches can vary so please ensure that you order sufficient tiles with an allowance for waste (normally 10%).
As with all ceramic tiles slight shade and dimensional variation should be expected between both batches and sizes of tiles. We do not recommend mixing sizes.