Started to grout kitchen floor with mapei ultracolor plus in beige - mixed to correct ratio but when dry the grout is nearer to an off white colour and is very patchy - what is the likely cause of this - also having trouble getting rid of haze from tile surface (glazed porcelain) - any advice appreciated.
Sounds like you may have used too much water when sponging off the excess grout. If you're lucky you might be able to just rub off the top surface of grout when its dry and it may be ok underneath. If not it will need regrouting. Most tile shops will sell grout haze remover if you're having trouble getting it off the tiles, its just an alkali solution that you'll need to dilute and wash the tiles with.