Help with silicone?!

I am making my very first facial prosthetic and I'm feeling very unsure of myself! I would really appreciate any advice, I went in feeling very confident and now I'm unsure about proceeding.

So, I have a lifecast made of Hydrocal White, and I sculpted my prosthetic with le beau touché (sulfur free) Chavant clay. I have decided to make my final prosthetic out of gelatine because I wasn't sure if I understood how to paint silicone and I didn't want to deal with problems painting quite yet.

My initial plan was to make the mold entirely out of plaster as countless YouTube videos show, but I'm less interested in this method now.

So here's where Im at, I don't have experience with silicone and I know it isn't compatible with many materials, I am now most interested in doing a silicone brush mold with a plaster shell. I know there are many different types of silicone to choose in different situations. Can I get some recommendations based on the materials I've used? Should I be safe using silicone with the materials I chose or do I need to be prepared for potential problems?

Thanks for any help, it is greatly appreciated!

I'm not experienced in making prosthetics but I've used silicones for making moulds & always the brush up way.
Your right, silicone rubber can react with everything causing it to curing problems. If its your first time I'd recommend sticking with a Tin cure (condensation cure) to start with, it doesn't react as easily as Platinum (Addition cure). One of the problems with a brush up mould is trapping air in the mould. I'd recommend using 3 detail coats ( without a thixotropic additive). You'll loose a fair bit of silicone as it runs off & pools, work on a clean area where you can scoop it up & re-apply it & allow each coat to be touch dry before applying the next. Then knock up your silicone with the thixo additive & start to build up the thickness. Whilst applying the thixo coats try not to trap air by using small spatulas & brushes to fill deep detail area's.
I've been experimenting with a kind of a prosthetic for one of my projects. One thing that might be worth a little research is the Shore Hardness of the silicone you intend to use. How do you intend to cast your prosthetic? by pour & gravity or will you inject? The way you intend to cast could have an effect on the type of silicone you choose to build your mould.

Like I say, my knowledge on this particular subject is limited but I hope its of some help

Hopefully someone with a bit more knowledge will add to this

I dont think you want to make a silicone mold for a silicone appliance.
you normally have a hard mould for this.
The normal equation is
Hard mould for soft end product
or
soft mould for hard end product.

Here is a video that might help


hope that helps

That's a great video, its given me some idea's

Thanks for posting Chefhawk :thumbsup

chefhawk said:

I dont think you want to make a silicone mold for a silicone appliance.
you normally have a hard mould for this.
The normal equation is
Hard mould for soft end product
or
soft mould for hard end product.

Here is a video that might help

https://www.youtube.com/watch?v=irAQ2TJre_0

hope that helps

Click to expand...

Thanks, I've watched this video several times in my decision making, but was ultimately scared away from the method by things like its description which reads "This is a fairly in-depth mold process that requires mold making experience with plaster molds." And in the video he says not to use the process on an important mold before you're experienced with it because many things you do can "make or break it."

Basically I have myself really concerned that I'll have made a mistake with one of the other steps and, I don't know, lock my molds together and make everything else completely unusable. I have used similar resins before (in completely different applications) so I am familiar with the material, I'll look further into using this method- thank you!

Gelatin is a good choice for a first prosthetic. I'd stick with ultracal for your mold. Some people do use silicone, but frankly you're likely to make some mistakes on your first try, so you might as well go for a more commonplace, simple, and less expensive technique.

How much detail, undercuts & awkward shapes are you dealing with? some pics might help

Okay, I avoided admitting what im doing because, well, it seemed like a good project at the start, and I maintain some things about it I think really do make aspects of it a lot easier, but now I realize a few things were just asking for trouble. I'm definitely going to see it through, though!

Im making a Handsome Jack mask, from Borderlands 2. I'm at work right now and posting from my phone so I'm not going to mess with posting pictures. I'm probably stupid for this choice, if I make the mask accurately I will have undercuts at the sides (the back edge and raised "sideburns") I was considering working around these things by adding the sideburns after somehow, and probably tapering that rear edge in the sculpt so it could be cast, and cutting the edge straight later. Mostly I'm realizing that the mask will be a difficult one to get out of a regular mold, so I was hoping i would find that a softer mold would be an option.

Thanks for all the replies!

yeah thats an awesome video, good post. If you wanted to keep the appliance route, I would suggest the ultracal mold with the gelatin, but have you thought of making a pull over latex mask? That could be easier, but pictures of your sculpt would help as well. Or you could try foam latex, but as a new person, that would be tough because you have to mix it correctly, and bake it. Was this for someone else, or for your own face?