I have some stone ballast coming from Arizona rock and mining. I haven't used real stone before and I notice that the DAP alex caulk works well for the flextrack but the excess comes up easily from the foam.
It sticks well enough for thr track but I wonder what adhesive will stick the ballast to this particular foam.
73
Bruce in the Peg
I don't apply my ballast directly to pink foam. After all, it's pink. At the very least, I paint the area around the roadbed (or beneath the track, if there's no roadbed) with acrylic craft paint. You don't want the pink color to show through, and if you don't paint it, it will show through.
In general, I also use some scenic material like Gypsolite around the roadbed, to give the ground some texture.
After that, I first wet it down with Isopropyl Alcohol, applied with a pipette, and then white glue thinned 1 part glue to 3 parts water. It's never been a problem regardless of what surface I've applied it to.
It takes an iron man to play with a toy iron horse.