I am casting rocks with Hydrocal in latex molds. It is difficult to remove the molds without damaging the casting, especially with one of the more intricate molds. I have tried using water with a bit of liquid dishwashing detergent without much success. Any recommendations?
Hi Roger,
I think you are referring to the small rocks mold as you mentioned the delicate parts. How long do you allow the hydrocal to set before removing it? Have you experimented with letting it set a longer or shorter time? I’ve haven’t had any problems with the molds breaking, but if the do occassionally break, I can still use them and work the plaster or hydrocal around the edges as I’m setting them in place. I don’t think I’ve been much help in solving your problem of breakage, though.
Jim
If your talking about micro detail sticking in the mold I think that’s normal and hard to overcome. I made several molds of tunnel portals that had some super detail and finally after letting it cure for several hours got them out of the mold without any major problems.
I did find out later that buying Hydrocal from a dental suppler that it work better, more bucks but better quality.
Mel
Modeling the SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield
With Hydrocal or plaster of Paris, there will always be some plaster residue sticking to the mold, tiny white bits against a black rubber mold. Cleaning this off the mold is normal maintenance. It does not affect the quality of the cast rock face; if you are getting big chunks of plaster sticking in the mold, that is a different story.
Are you casting the rock in place against a hillside or letting the plaster harden in the mold?
Casting in place.
I was having difficulty removing castings from WS molds without breaking the Castings. I was about ready to trash them, when I found a mold release spray at Hobby Lobby. Had no problems since. The spray is where they have plaster in the crafts section. In casting in place, I do not remove my molds until I can feel the plaster beginning to get warm. Also, I am not pleased with the results I get from WS light Hydrocal.