>>1014784 I use similar stuff to this https://www.bunnings.com.au/dunlop-1-5kg-ultra-white-flexible-coloured-grout_p6829751 only need to mix whatever amount you need with water, $12 worth will last years, and you can just use a wet damp sponge to clean up any excess. I also have used the stuff in a cartridge but it was harder to get a nice clean finish as it needed I think turps to wipe away any excess.