I didn't see a "Basing" forum, so I threw this in here. Mods, If there is a better place please toss it over.

I'm starting to base my army, Necrons, and I having some trouble. Here are my problems/questions:

1: What sand/gravel do you use to base your models? I tried using dirt/sand/gravel from my parking lot trying to save a few bucks, but I think I might break down to by some. Is one size of GW modelling sand better than the other?

2: What ratio water : glue do you use when thinning down your white glue to seal the basing material on? Or do you use a completely different method?

Thanks in advance!