"scenery black" mixture for painting mountains and rock?

Sure! I used the cheapest black paint I could find at Home Depot.  Check the "oops" counter.

nice OOPS BLACK

AlanRail posted:

nice OOPS BLACK

OK, to be precise: OOPS BLACK-ish. 

From Dave Frary's Scenery Book:

"Dilute flat black paint with equal parts of water and then mix in 3 parts basic earth color with 1 part diluted black."

John H posted:

From Dave Frary's Scenery Book:

 

"Dilute flat black paint with equal parts of water and then mix in 3 parts basic earth color with 1 part diluted black."

 

That sounds more like a wash. I don't think you want to dilute a base coat used for OP's purposes.  Plus, if you are a member of the Church of the Black Mountain Base Coat, you want true black, not brown, since the purpose is to get the deep shadows in place before you dry-brush on the highlights.

That sounds like an excellent recipe for a subsequent layer, though.

My biggest concern is applying a uniform colored base over the cast rocks and the sculptamold. If the paint mixture is too watery it will be clearly seen where sculptamold was used in between the rock castings.

Here is the  link to Daves free video and there he explains base coat and detailing rocks

http://www.mrscenery.com/vid2_13A.html