sorry for the late reply the mrs took me out tonight with out notice its becoming a latishac world we are working in today .so i need to know the slip value of all my tiles including new batches of the same tile .have had no problems .but i do no a few tile shops that have come unstuck using r rating that were done on tiles two years ago but today fail that rating. and i have a few shops that want me to check other tiles they sell before they spec them