I would like to know the reason play sand cannot be used for paint texture. Is it because it is dirty? Could it be rinsed? This would save me $$ as I already own a bag of it.
Play sand is dirty and it could be rinsed but this isn't the main reason not to use play sand in paint. It is heavy. The density and weight of play sand will make it sink to the bottom of the paint, in a paint pan or bucket for rolling. It will be difficult or impossible to have an even distribution of sand for the texture.
It is better and easier to use the pumice or ceramic based paint additives. The results will look much better.