I had a question aboout molding rocks with alginate. Can I just put them in a bed of sand and pour alginate over them then use that mold and make a casting out of plaster or something else liek that plastic or whatever? Any tips on making some fake rocks would be good. And I tried making some by mixing urethane and cotton and putting it in hot water and they didnt turn out so good maybe I was ising the wrong cotton or something I just use cotton balls pulled apart and the rocks looked liek big fluffy cotton balls stuck together. Any tips on that would be good too. Thanks for any help, Kevin
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This is how I have made rocks. Order some latex mold builder, I believe WASCO carries it. Find a rock that you'd like to make a copy of. Brush on a coat of the latex, let it dry to a tacling feeling, then brush on another. Do this for the total of four or five coats. I fthe rock is a large one, you may want to use some sort of cheese cloth to help reinforce the mold. Once you have applied the last coat let it cure completely, usually overnight or a day. Now you can just peel the latex mold off of the rock you are ready to make a copy of it. Mix up 50/50 bondo and resin add your catalyst and pour into the latex mold. Rotate the mold so that the bondo covers all sides of the mold. Keep doing this until the bond kicks. When it starts to heat up remove the latex mold so as not to "cook" it. Set it aside until it cools. Now you can make another batch of bond and resin and make another rock if you wish.
Another way to make rocks is to mix up some plaster and water. Add some paper pulp - you can buy a large bale of it from Lowes' of Home Depot it's the shredded paper used for blown in insulation. Mix a handful of that to your plaster until a uniform mixture. Now spread it onto any surface that you wish to make look like a rock. Or you can even make small round shapes out of it. Then once dry you can mix some black tempra powder with water a give it a wash coat to give it some color. You can even use other colors if you wish.
Hope this helps some!
Andy