I need a few small rock castings along the ROW on the East Berlin branch, so I figured I'd use a couple of the Woodland Scenics rock molds I had on-hand.
Problem is (or perhaps, turned out to be) that the Plaster of Paris I had on-hand is probably about 25-30 years old. But it was unopened so I figured it'd be ok. So I mixed it up according to the directions...
... and filled up the molds, scraping & leveling them off with a little putty knife.
Then, I waited for over a week . . .
After over a week, the large rock casting on the left is STILL not cured (see how it's a bit darker/grayer than the other, whiter castings?)
But the worst was when I went to take the castings out, they were all so soft and crumbly. Totally unusable! Certainly nothing like my
So - what did I do wrong? Heh - could probably be a number of things, but I'll start by purchasing some new Woodland Scenics Lightweight Hydrocal and will try again...