In reply to Hotbad Peteel:
We have the sand from when the last part of our wall was painted. The guys who did that aren't around any more, managed to graduate and escape.
So im just really after proportions i think. Going to have a play later anyway before we start painting the wall. I've heard mixing a bit of PVA glue might be the answer. But ive also heard that the paint may change colour with the sand? Never done this before, hence seeking advice from those who have.
Iain