My apologies to Scenic Cement

Well, you were not alone in your confusion about it the first time you used it.  I had the same experience - bought some used it, and was disappointed - it was wet and did not hold well.  Only when I went back and picked up the trees much later did I realize the glue had slowly dried to a remarkably tacky finish that reached out and grabbed flocking!  It's good stuff, and probably designed to take a long time to dry to tacky - with the thinking that most users will paint it on a lot of trees at once, taking a long, long time do just that before coming back through for the second pass with the flocking. - so they make it set up nice and slow.

I love the stuff!  Used it to glue down all of my track ballast!  Matt

According to the Woodland Scenics web site S191 "Scenic Cement™ is a ready-to-use matte adhesive for Ballast, Turf, etc."

While S195 "Hob-e-Tac™ is a multi-purpose, water-soluble, high-tack adhesive. It is perfect for making trees and attaching Clump-Foliage™, Field Grass and Fine-Leaf Foliage™. Hob-e-Tac can also be used as a contact adhesive."

Sounds like you had the wrong product for the job. You're supposed to let Hob-e-Tac dry a bit before applying foliage, but it doesn't take nearly as long as using Scenic Cement would.

Len2, you are right.

FWIW Elmers white glue diluted with water is the same thing. In addition, once I have it diluted to a consistency I like, the bottle works great for flowing the mixture onto ballast.

I think one other ingredient must accompany the white glue. Dish soap maybe???

Its recommended that when glueing ballast that you "pre wet" the ballast with plain water with  a few drops of dish soap per gallon.

This helps break the surface tension of the dry ballast making it absorb the glue mixture better.

I was lazy and skipped the "pre wetting", the ballast set up just fine. Having said that, I ballasted  fastrack so the depth of the ballast is not nearly what it would be with a "road bedless" track like atlas or gargraves. I'm guessing "pre wetting" is more critical with the more realistic track types because of the thick layer of ballast between the ties and on the edges.