I've just had some black & white polished porcelain tiles laid by a professional tiler. He stopped grouting after 2 tiles because he says they are faulty in that they have a number of invisible surface scratches or cracks which pick up the black grout and the end result would look like hairs all over the floor. What can I have done to stop this happening? Is it a case of taking them up (30m2) and starting again?
Sorry if this is way too late to help, but it sounds like the tiles needed a crackle glaze first. You can apply the glaze before any wet cuts are made and then again before the tiles are grouted and then once more for luck once the grout has dried. This will stop the problem.
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