my first casting project..

[Doug (costcoman)]

Which one is the real rock?

[JonHarleTX]

is it the one on the left?

[4txdrm]

First of all they both look great, I would assume that the one on the right is the reproduction only because the little warts on it, If I get air in my mold it will leave a void so when you pour the cast the cast will now fill all the voids and leave little bumps on project. If the one on the left is the ropo then you ground all of the little warts off to make it smooth. There is something going on because there are several areas not the same unless it's the camera angle.

[4txdrm]

I am fore sure not an expert but if i was right, all the air void can be eliminated by degassing your rtv or you can just paint or rub on a couple of skin coats on what you want to replicate.. Then proceed with molding process weather it be keep building up or damming and pouring..

[Doug (costcoman)]

your right the one the left is real, not sure what your talking about by degreasing rtv, I did this with $1.50 tube of Wal-mart silicone caulk a and a little thinned bondo.       Doug

[#1 headhunter]

One thing for sure, We have some pros on this site that can spot the difference. I can see the difference since someone pointed it out. I am very interested in doing some casting, if I could ever get caught up on these other projects.

[4txdrm]

LOL!! I actually said degassing not degreasing LMAO!!  A degassing chamber pulls all the air out of you rubber by vacuum, by doing this and applying correctly you will eliminate air in your mold.  Although if you are just using regular silicone you will not have to worry about it,,  You can actually achieve good results with cheap silicone. I have always used RTV rubber from silicone INC but I did try the regular silicone one a rock after reading one of the best tutorials ever on this site, I found if you use the acrylic paint as a activator and you use your finger to rub in really good snap all the little are bubbles and build it up in 3-4 applications you can get really good results but the mold won't last as long. RTV rubber is more for production mold. You can use the rtv the same manner build it up by hand or paint brush.. You can also add cabosil to thicken rtv but you would need to put a skin coat or two on before you do your build up coats. This will insure you don't get any air.  If anyone don't understand and would like to ask questions feel free to email me..  I not a pro by no means but I have went through 15-20 gallons of Rtv in the last 2-3 years.  Hope this helped

Smith Taxidermy

[Doug (costcoman)]

Thanks for all the info, I actually was just trying to do this to see if I could do it I dont have much time to do allot of molding, however this was very fun, I could see how this could be very addictive.I am actually more interested in doing fish heads and maybe later trying fish. By the way what kind of chamber do use to do your (DEGASSING) is this something you bought or is it something that can be made...             Doug

[4txdrm]

I made mine useing 12 pvc with 1 inch plexy glass to seal bottom and a silicone gasket on the top and another piece of one inch plexy with gauges and vacuum hooked to it. If I get a chance tomorrow I will post a pic.

Smith Taxidermy