I am working on slip casting plaster of paris (as opposed to rotomolding). I am using an unopened box of plaster that i'm not sure how old it is. I am trying 3d printed molds and oomoo smooth on molds. I am casting parts slightly smaller than a golfball. I am having several issues that google searches did not help with.
1. The plaster is extremely watery at 1:1 mix. I have some casts that are still damp after 36 hours.
2. At thicker mixes, the plaster loses it's liquidity at smaller ammounts. So in the mixing cup it's like batter but in the mold it's like jam. Thicker mixtures still take more than a day to be dry to the touch.
3. Smooth on oomoo seems hydrophobic. The plaster fails to coat the walls thicker than ~.5 mm.
4. Even watery mixtures tend to pool up and congeal hen I dump the excess plaster, leaving me with half a solid golfball and the other half is a super thin shell.
I would like to be able to coat insides enough to get 3 mm thickness. I would like to be able to eject the part after an hour to reuse the mold. Is plaster not the right thing for this? Should I be using hydrocal or something else?
1. The plaster is extremely watery at 1:1 mix. I have some casts that are still damp after 36 hours.
2. At thicker mixes, the plaster loses it's liquidity at smaller ammounts. So in the mixing cup it's like batter but in the mold it's like jam. Thicker mixtures still take more than a day to be dry to the touch.
3. Smooth on oomoo seems hydrophobic. The plaster fails to coat the walls thicker than ~.5 mm.
4. Even watery mixtures tend to pool up and congeal hen I dump the excess plaster, leaving me with half a solid golfball and the other half is a super thin shell.
I would like to be able to coat insides enough to get 3 mm thickness. I would like to be able to eject the part after an hour to reuse the mold. Is plaster not the right thing for this? Should I be using hydrocal or something else?