After the latex has dried, take a shallow card board box and place it over the mould, taping it down to the sign board to hold it in place.


The mould area is fairly large, and the plaster is pretty heavy, so I wanted to add support on the back of the mould so that it would hold it’s form better. I did this by squirting the back of the mould full of “Great Stuff” expanding foam. Shoot some in and smooth it over the mould with a plastic putty slick so that you get a nice smooth layer without any air gaps,... then you can just shoot the rest in and let it all harden up.


Once everything is dry,... just turn it all over and pull your tank out of the latex. You can see from this picture that I didn’t smooth the first coat of foam out and ended up with some small air pockets. The mould still worked fine, but the weight of the plaster did cause the cast to come out with a few minor bumps. These easily sand off, but why not try and start out as smooth as you can. Ok,... we’re ready to try a cast and the first step is to coat the mould with a release agent that will allow you to pop the cast out without wrecking the latex mould. I used a silicone spray that is used to protect the rubber weather strips on car doors. I can’t stress enough,... don’t do this in your painting area. Take it outside where you won’t contaminate your work area with silicone spray as it will cause fisheyes in your paint.


Read the instructions on the plaster bag,... it mixes about two parts plaster to one of water. You only have about 10 minutes after you start mixing to pour the mix into the mould before it starts to set up, so you have to work pretty quickly. I found that it worked better when I added the plaster into the bucket of water instead of the water into the plaster,... it just mixed easier. You want to try not to stir too much air into the mix, and that’s where a mixer comes in handy. Set to turn slowly, it mixes quickly and smoothly without beating a lot of air bubbles into the mix..


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32