Really? It must be the Cornish sand
First I paint the base and let it dry. I then paint on PVA glue and then sprinkle on my Cornish sand (Straight from Church Cove beach), tapping off the excess and then letting it dry. I then base coat with a watery coat of Bestial Brown, let that dry and then dry brush with Vomit brown. Chaos Black goes around the rim to finish it off.
The sand I use is multicoloured and the watered down basecoat allows a small amount of variation in colour before the dry brush. Depending on whether I want variation, I'll sometimes sculpt GS blobs on the base to add some extra texture...
All in all, really, REALLY basic
Glad you like them though