The joint widths are generally derived from the difference between the nominal size and the work size, or are specified as recommendations in the tiling standards.
Recommended joint widths:
Side length : up to 150 mm : 2 mm
more than 150 mm : from 2 to 8 mm
There are no restrictions on the choice of joint colour for glazed vitreous tiles. Unglazed porcelain stoneware tiles should not be jointed with coloured jointing mortar, as its colour pigments, in particular jointing compounds containing carbon and graphite, could stain the surface. Residual films are to be removed with care while still fresh. Test jointing is essential; please observe the instructions of the jointing material manufacturer.