Casting materials: pros and cons???


Active Hunter
Hey there,

I just wanted to know if anyone has the low-down
on most of the popular casting/molding materials out
there? I keep seeing things posted about non-fiberglass
resins, fiberglass, etc. Can someone tell me about the
pros and cons of working with these materials; what
the finished products of these materials come out like;
and what ARE the most commonly used materials for
casting/molding? Any help would be greatly appreciated.

BTW- I'm not trying to recast anyones work...just looking
into sculpting/casting my own stuff. :)
Fiberglass can be dangerous if you're not careful, but the results are fantastic. First go get yourself a copy of Thurston James' book on molding and casting. It will have info on more casting processes than you will need, but it is a valuable resource. I made my gauntlets first out of sintra and bondo, and used silicon RTV with a plaster mother mold for my molds. I cast them with gel coat and fiberglass. Making your own molds will be time consuming, and a little expensive, but I think well worth your effort. Silicon RTV was the most expensive part of the process, but it is the coolest. It comes as a two part system; your base is a thick Elmer's glue like substance that is activated when you mix it with the catalyst. It takes hours for it to set up, but when it does it is very flexible. This makes pulling out your cast a breeze, and it requires no mold release. Get the book, and check out for your supplies. Good luck, and please PM me if you have any questions.
Currently, we are using micromark rtv and resin for casting, anyone have any better brands? It might be the temperature, but our resin just turned into a pile of jellyfishlike mess. We have used other stuff before with a 10:1 mixing ratio, that was better, but can't remember the name or find the link.
I tried some RTV to make a mold for a part that I wanted to cast, and the RTV ADHERED to the part! I had to cut it off of my part, and then do some restoration to it! It was made by Permatex, I believe. A very horrible RTV experience! :eek:

I really need to find something reliable that I can create molds with, then I need to find a good resin. Seems like Spidey mentioned some type that was a 1:1 mix ratio...

The part that I'm trying to mold is plastic, so whatever I use needs to be plastic/resin/poly-friendly...

Any suggestions? :)
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I know there is a company called Smooth-On that has all sorts of casting/molding materials. I have never used any of these types of products before, so I can't give you any first hand knowledge of how good or bad they are or what the pricing looks like. Check out the special effects link on the homepage.....they have some really cool stuff!!!
Smooth-on is the way to go. I have used their products for a couple of years and they are great. They have great customer service, fast shipment and great prices. Their RTV doesn't harm the original and is easy to use. You can get several different types of resin through them depending on your needs. Good luck!

Fetthunter wrote:

Which "getting started" kit would be best for me? The "Silicone SuperSampler"? :confused

That one would be good to start with. It gives you a chance to play with it a little without shelling out too much cash. Don't plan on casting anything real big with it though.

Spidey2222 wrote:

Don't plan on casting anything real big with it though.

I figured as much. :facepalm

I guess I might as well go ahead and use that $25 and get a larger quantity of something else that I can get some "mileage" out of.

I was looking at that "OOMOO" stuff because it's a 1:1 mix and you don't need scales, but they say that it isn't as resistant to tearing as the "MoldMax" type is (but it's a 10:1 mix, and you DO need scales for it!).

i agree with Boba Phat... i cast Gene Simmons Boot shells and i made a mold with RTV from TAPS Plastics..... I used Quick cast for cast. it is a very hard durable PVC plastic, excellent details and it dries in about 10 - 15 minutes. it is a brush on or pour on material and if you get it about 1/8 or more in thickness it will rival fibreglass in strenghth and wont take years off your life lol .. the only draw back is it has to be about 70 degrees before mixed so i just leave it in a warm room all day before i use it

Fetthunter wrote:

..........(but it's a 10:1 mix, and you DO need scales for it!).

I have never used scales. You can either just use a measuring cup or just eyeball it like I do most of the time. Use one of the big glass measuring cups (buy one, don't use one out of the kitchen unless you want you wife to kick you butt). After your pour the mix into your mold, pour out as much as you can in the trash then let what's left in the measuring cup cure over night and you can just pull it out. If you try to clean it up while it is still gooy, then it will make a mess and it will never clean up.
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