I took a look at that product... I'm not sure I like it, but it may be worth a try.
Today I officially finished all the mainline ballasting. Meanwhile the sculptamold is still drying. Unlike the Hydrostone which sets up chemically, this product seems to need to dry as well as set-up plaster-like. I took a look at my ballast inventory, and much to my disappointment, I'm afraid I'm going to have to buy another bucket. I won't be consuming the whole thing and have no idea what I'm going to do with the surplus. Perhaps another O'gauger will see an ad on Craig's list for 20 pounds of white roofing granules and think it's a good deal.
I'm going to mix the yard ballast with black, and earth tones to make it look more yard-like. In fact, it should probably be more mud and cinder-looking and show no ballast at all. It's a big surface area and I don't want to have to buy bottle after bottle of WS colored ballasts for this last part of the job.
Here's the last area of mainline trackage with ballast. This one piece of track is the most difficult to get to the layout and I had to sit on the layout to get to it. I use a couple pieces of heavy cardboard to spread my load and keep me from sitting directly on the tracks. The layout—all L-girder—doesn't even creak when I get on top. It's a very strong way to build.
Those white wedges you see are pieces of beaded Styrofoam that I used to extend areas where there wasn't enough subroadbed sticking out to hold the ballast. The remainder of those open areas will have to be covered up with something on which to landscape going forward.
Here's the bit of Sculptamold that still damp after almost 48 hours of drying time. I'm not particularly happy about that, but I had something else to do in finishing the last bit of mainline. When discussing the ballast consumption with my wife, she asked if I put it on too heavy. I said I didn't think so. To back up my opinion, there's that interesting GE add with the talking car from the old TV show. Knight Rider, discussing how smart the new GE locos and then it paces the engine. It's a N-S engine GE44EVO and then there's a nice overhead shot that shows how wide the ballast pile really is, and I didn't overdo it, not by a long shot.
Sculptamold has a nice organic texture that will look good when painted and covered with vegetation.