When Citadel released their first incarnation of Roughcoat it was mentioned in the literature that it was water-based so wouldn’t melt expanded polystyrene.
That first incarnation sold well and I never managed to get a can, then I heard from one GW store that it had been withdrawn as the nozzle would clog after using it just once and they had had quite a few complaints.
When it was re-released I got a can, but just assumed it was still water-based…
It’s not!
After spraying my scenery tiles, I noticed the other day that they had melted…
Luckily it wasn’t too bad and might actually add to the effect I am trying with the scenery, I will take some photographs later.