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Hello, everyone. I have a question, what's better silicone mold vs plaster for resin casting? I've sculpted a model with high amount of details on it. Already tried silicone mold and it totally sucks, it doesn't take all details no matter how hard I pushed on putty, liquid silicon had same result. Don't think that im a noob in casting but now im looking to try plaster mold. I spent a lot of money for silicone already and before buy a plaster i decided to ask you guys if you have any experience with plaster mold.

Ive seen plaster used to bolster large silicone molds, to save on money, and strengthen the silicone from collapse over large surfaces. Ive never (yet) seen it used to make a mold of a model.
What silicone are you using?
Can you describe how you set your model up to get it molded using the silicone?

Ok, my model was in a modeling clay and frames around it. Easy mold putty has been pushed from the top covering all surface of it. When it's been cured i repeated same process with other side. Also i used corn oil as a lube to prevent sticking 2 rubber pieces. And after an hour of curing i disassembled it and tested it. But it failed, because even on rubber mold was able to see unclear details of model. It seems something wrong with rubber because it doesn't want to take shape of my model. U repeated that process multiple times and all was same. First i though because of oil then i was decreasing amount of oil each time i repeated that. No idea....

Unless you are making a press mold I don't see how one would demold something from plaster without destroying the mold.

Also, putty molds don't work as well as proper liquid silicone rubber molds.

Try using Smooth On's Oomoo. I use it to great effect and it pulls detail as well as anything on the market.

For more info on the process and products people use: http://www.dakkadakka.com/dakkaforum/posts/list/307451.page

Silicone rubber for me.
I used to use a tin-catalyst rubber but have switched to a platinum catalyst rubber for my resin work. These are mix-up two part rubbers (a+B) not any kind of putty.

Neither had issues resolving detail from the original form, and indeed, both will resolve fingerprint ridges.

Oomoo 300 is a miracle worker. 50ish bucks +shipping unless you go with dick blic art supply, or have a local supply shop, and thatll buy you a set of oomoo 300 and smoothcast resin. If you already have the resin to cast with, then for about 25-30 bucks +shipping you can get just the oomoo. The problem you will have with the press mold stuff is, is that it does not "seep" into the models details (if i understand how the stuff you are using works). The oomoo will seep into it, and the airbubbles will rise. Sounds like you have your set up correct with the mold box and molding putty (make sure its sulfur free, you probably know that already).

Oomoo allows you to have basic tools and equipment (two clear cups, something to mix with, and one eyeball) to get outstanding results. No vacuum chamber needed.

Hello, once again! Recently bought plaster, now going to try make a plaster mold. I decided to go for plaster because of money ( cheaper) and some other guys told me that there is a way to design a plaster mold that you wont need to destroy it XD.

Ok! Let us know how it goes, it would be interesting to find out how it works!


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ANd how much did it cost?

nemesis271989 wrote:Hello, once again! Recently bought plaster, now going to try make a plaster mold. I decided to go for plaster because of money ( cheaper) and some other guys told me that there is a way to design a plaster mold that you wont need to destroy it XD.

That would depend entirely on what you are casting and what you are casting it with.

I have used plaster moulds to cast stuff in before - but these items were rubber and flexible (polyurethane rubber 'stunt guns').
Anything rigid has a high likelyhood of needing the mould broken to extract it (UNLESS you make it a multipart plaster mould.) - this is how many clay slipcast moulds are made. You assemble the various parts of the mould, and pour the clay slip (liquid made up of clay, flow improvers, water and other minerals) into it. When it has set firm, you dismantle the mould and demould the casting so that it can dry better.

That's what im going to do- multipart mold with minor rubber inserts. I will be working on it if it will be successful I will post tutorial and sketches that I made.

Well, if its not successful you should post pictures, etc also. That way we all can learn, and even maybe suggest what alternatives you could have taken.