Hi Brian,
Over here in Ireland, especially in rural areas, we still burn turf (dried out bricks of peat) in our open fires, It burns down completely to ashes. I use turf ash for sand, it's a fine yellow sand-coloured flour-like powder, perfect for desert sand. On a lot of dio builds I've seen modellers use white powder and spray it a sandy colour, with the turf ash you don't need to. Brush your ground work with a diluted mix of PVA glue, sprinkle on the ashes with a sieve, leave it overnight to dry and shake off the excess ash.
PM me your address and I'll send you over a tub of it.
Here's some on a base I made last year.
