I find grouting a bit of a black art to be honest. When mixing, you need to aim for the constancy of soft whipped cream, sort oflike when it comes to peaks that don't collapse. A good test is to see how easily it falls of the float. I find it should just about slide off. if it is runny it is no good and if it sticks to the float it is too thick. Practise, as always makes perfect. You just need to take your time. Always add powder to water, a bit at a time, and not the other way round.
