Prep Ultracal mold for silicone casting

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DarkSculptor

New Member
I've got a 2 part Ultracal mold in which I'd like to cast a silicone part. Actually 2 different molds.
Read online some people just wax-on/wax-off vaseline plus some mold wax (like with casting urethane foam?). But a pro friend was telling me I had to seal it and do all kinds of other crap to SAFELY cast silicone.
What works best and is the cheapest?
Also could use some reccoes for soft silicone brands to use. One mold is a prop (head), the other is a prosthetic (face).

Cheers!
 

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udog

Active Member
Silicone won't bond to Ultracal. I wouldn´t use wax nor vaseline. A light soap release could help demolding but I´ve casted silicone in stone plaster with no release ok.
Sealing can be a good idea.
For a foam filled prop I would use something like Dragon Skin or similar. As for soft silicones (for the prosthetic) Ecoflex could be an option.
 

DarkSculptor

New Member
Silicone won't bond to Ultracal. I wouldn´t use wax nor vaseline. A light soap release could help demolding but I´ve casted silicone in stone plaster with no release ok.
Sealing can be a good idea.
For a foam filled prop I would use something like Dragon Skin or similar. As for soft silicones (for the prosthetic) Ecoflex could be an option.
Many thanks! I suspected as much.
Two questions though: You said sealing can be a good idea. Seal with what, exactly? Shellac? Crystal Clear? How many coats? The surface still has some patches of urethane acrylic coating leftover from the sculpture. Do I need to get all that out of there first to avoid problems? (sorry, more than 2 questions)
Also, I can either cast in a solid (soft) silicone like EcoFlex 0-10 OR give it a dragon-skin surface and use their Ecoflex GEL to “fill”
(What I was told by the pro friend I mentioned).
Which would be best for a soft casting? Needs to be stretchy/realistic but also can’t risk tearing at all.
Thanks again!
 

udog

Active Member
Many thanks! I suspected as much.
Two questions though: You said sealing can be a good idea. Seal with what, exactly? Shellac? Crystal Clear? How many coats? The surface still has some patches of urethane acrylic coating leftover from the sculpture. Do I need to get all that out of there first to avoid problems? (sorry, more than 2 questions)
Also, I can either cast in a solid (soft) silicone like EcoFlex 0-10 OR give it a dragon-skin surface and use their Ecoflex GEL to “fill”
(What I was told by the pro friend I mentioned).
Which would be best for a soft casting? Needs to be stretchy/realistic but also can’t risk tearing at all.
Thanks again!.
Could be with crystal clear, not shure about shellac. Remember that anything you use with platinum silicone for the first time should be tested first to ensure there is no inhibition. But if you are using UC30 I wouldn´t worry about sealing. I´ts not a very porous (the reason for sealing) material, something else would be Hydrocal or similar which is very porous. You´re safe with UC without sealing.
As for the patches of urethane acrylinc coating (what exactly?), I would try to remove as much as possible. Could affect your texture among other issues like inhibition, but don´t know what material it is and how long it has been there.
The silicone choice depends on what kind of piece are we talking about and what use you are thinking of.
For a display piece a full silicone casting could be an overkill (and expensive) if it´s not intended for anything else. Could be foam filled (PU foam). For a display head I would go with thickened brushed Dragon Skin 10 (or similar) and fill it with flexible PU foam. Wouldn´t use ecoflex or a soft one for a display pieces, not full either.
Unless you have other kind of plans for it.
A prosthetic is something else. You normally want it soft. But there are many kind of prosthetics too. For example (thinking of silicone) you can make them encapsulated or a one material part.
Encapsulating allows getting a softer casting, but generally going down very soft (with Deadener or Slacker) means you get a sticky tacky silicone so it must be encapsulated with another layer. This can be another silicone or Bald Cap material or others (years ago Glatzan). These last ones (Bald Cap) have the advantage you can easily blend edges with alcohol. But they are a one use prosthetic in first instance.
If you want it more durable you should encapsulate with silicone. Ecocflex GEL and anotther silicone to encapsulate could do. Blending the edges will be different in that case (with silicone then, Skin Tite or similar for example). Won´t last for ever anyway, depends on the number of applications and the build up created with whatever adhesive you use.
If you don´t want to encapsulate, you could try with straight Ecoflex 00.30 or similar. Depends on where the prosthetic goes on too.
 

DarkSculptor

New Member
Could be with crystal clear, not shure about shellac. Remember that anything you use with platinum silicone for the first time should be tested first to ensure there is no inhibition. But if you are using UC30 I wouldn´t worry about sealing. I´ts not a very porous (the reason for sealing) material, something else would be Hydrocal or similar which is very porous. You´re safe with UC without sealing.
As for the patches of urethane acrylinc coating (what exactly?), I would try to remove as much as possible. Could affect your texture among other issues like inhibition, but don´t know what material it is and how long it has been there.
The silicone choice depends on what kind of piece are we talking about and what use you are thinking of.
For a display piece a full silicone casting could be an overkill (and expensive) if it´s not intended for anything else. Could be foam filled (PU foam). For a display head I would go with thickened brushed Dragon Skin 10 (or similar) and fill it with flexible PU foam. Wouldn´t use ecoflex or a soft one for a display pieces, not full either.
Unless you have other kind of plans for it.
A prosthetic is something else. You normally want it soft. But there are many kind of prosthetics too. For example (thinking of silicone) you can make them encapsulated or a one material part.
Encapsulating allows getting a softer casting, but generally going down very soft (with Deadener or Slacker) means you get a sticky tacky silicone so it must be encapsulated with another layer. This can be another silicone or Bald Cap material or others (years ago Glatzan). These last ones (Bald Cap) have the advantage you can easily blend edges with alcohol. But they are a one use prosthetic in first instance.
If you want it more durable you should encapsulate with silicone. Ecocflex GEL and anotther silicone to encapsulate could do. Blending the edges will be different in that case (with silicone then, Skin Tite or similar for example). Won´t last for ever anyway, depends on the number of applications and the build up created with whatever adhesive you use.
If you don´t want to encapsulate, you could try with straight Ecoflex 00.30 or similar. Depends on where the prosthetic goes on too.
I used an old can of “Min-wax Polyurethane clear gloss” to seal the sculpture and just made this mold less than a month ago. Could remove this with paint thinner or acetone? The layer isn’t thick enough to matter as far as surface cosmetics though. The piece (prop head) is small and may be partially animated so not interested in foam (done lots of that before) this time.
The other mold is a prosthetic, yes. I don’t want it to be a one-time use casting, if possible. I would use pros-aide when I wear it. It’s not for a production or anything either, just a personal project to gain experience with casting silicone. I doubt I’d wear it more than twice ever (just for photos). So I’m assuming the encapsulated version is always the more professional choice, yes? That would be more expensive, actually. Does no one ever just cast prosthetics in straight 0-10 ecoflex? Too stiff still? I'm not super worried about “feathering edges” as it’s a full-face prosthetic with a wig hiding flaws.

Thanks again for your invaluable advice, Sir!
 

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udog

Active Member
I used an old can of “Min-wax Polyurethane clear gloss” to seal the sculpture and just made this mold less than a month ago. Could remove this with paint thinner or acetone? The layer isn’t thick enough to matter as far as surface cosmetics though.
If it doesn´t affect the texture, make a small test with silicone on that part to see if it cures properly. Probably paint thinner if not, you will have to try.
The piece (prop head) is small and may be partially animated so not interested in foam (done lots of that before) this time.
Ok, thats something else. will depend on how you are planning to animate it (mechs, by hand?), but full is a better idea then (you could also create cores to not make it full and too heavy).
 

udog

Active Member
The piece (prop head) is small and may be partially animated so not interested in foam
Do you know Soma Foama?

The other mold is a prosthetic, yes. I don’t want it to be a one-time use casting, if possible. I would use pros-aide when I wear it. It’s not for a production or anything either, just a personal project to gain experience with casting silicone. I doubt I’d wear it more than twice ever (just for photos). So I’m assuming the encapsulated version is always the more professional choice, yes? That would be more expensive, actually. Does no one ever just cast prosthetics in straight 0-10 ecoflex? Too stiff still? I'm not super worried about “feathering edges” as it’s a full-face prosthetic with a wig hiding flaws.

Encapsulating allows to achieve very soft silicone and if done with Bald Cap material or similar, good blending edges. The choice of using it will depend on the use. More expensive, yes, more different materials in one piece.
For what you say I´d dismiss that one, it would be weaker, specially for such a big piece (in my opinion). Try a soft Ecoflex. Never used 00-10, could do. 00-30 is the standard for silicone masks and your piece resembles that.
As for the adhesive, Telesis type or Skin Tite are more used for silicone.
Thanks again for your invaluable advice, Sir!
Anytime I can help.
 

DarkSculptor

New Member
Wow
Do you know Soma Foama?



Encapsulating allows to achieve very soft silicone and if done with Bald Cap material or similar, good blending edges. The choice of using it will depend on the use. More expensive, yes, more different materials in one piece.
For what you say I´d dismiss that one, it would be weaker, specially for such a big piece (in my opinion). Try a soft Ecoflex. Never used 00-10, could do. 00-30 is the standard for silicone masks and your piece resembles that.
As for the adhesive, Telesis type or Skin Tite are more used for silicone.

Anytime I can help.
Wow, Somafoama looks cool, but way outside my budget.
Thanks for the heads up on adhesives and all that. I think I'm gonna try solid 0-10 or 0-30 for now. I have some powered pigments that I used for hot melt vinyl to tint. Yea it's too complicated to core already, though I've done that.
By "a light soap release", you just mean dish soap or something else? Bar soap?
This is my Vincent Price that I've needed to cast in silicone (forever!).
 

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udog

Active Member
Wow

Wow, Somafoama looks cool, but way outside my budget.
Thanks for the heads up on adhesives and all that. I think I'm gonna try solid 0-10 or 0-30 for now. I have some powered pigments that I used for hot melt vinyl to tint. Yea it's too complicated to core already, though I've done that.
By "a light soap release", you just mean dish soap or something else? Bar soap?
This is my Vincent Price that I've needed to cast in silicone (forever!).
Yep, Soma Foama is expensive. But interesting material to try. Careful if you do one day if used in closed molds. Make sure they´re strong, grows with a lot of strength.

Soap release is a release used for plaster/plaster for example. Molding and casting suppliers should carry it. There are also soap based sealants or similar. Better buying a dedicated one than making your own (with dish soap for example), but you could.
An example:
But as said before, I think you are safe without it. It´s something I´d use in case I had a very porous or harsh textured material to mold on and was afraid that the rubber would "cling" to the plaster surface and end up damaging it. Or if I was going to pull many castings to protect the mold. Not the case as I see it.
You can always make a small test in an uncompormised area when you buy silicone and see how it works.
Nice Vincent Price by the way.
 

DarkSculptor

New Member
Yep, Soma Foama is expensive. But interesting material to try. Careful if you do one day if used in closed molds. Make sure they´re strong, grows with a lot of strength.

Soap release is a release used for plaster/plaster for example. Molding and casting suppliers should carry it. There are also soap based sealants or similar. Better buying a dedicated one than making your own (with dish soap for example), but you could.
An example:
But as said before, I think you are safe without it. It´s something I´d use in case I had a very porous or harsh textured material to mold on and was afraid that the rubber would "cling" to the plaster surface and end up damaging it. Or if I was going to pull many castings to protect the mold. Not the case as I see it.
You can always make a small test in an uncompormised area when you buy silicone and see how it works.
Nice Vincent Price by the way.
Thanks! Yea I'm going with "Mann easy release 200" for release, just to be safe. I remember "soap" now from college. Never used it then (vaseline), for plaster/plaster casting. I'll keep it in mind.

Hopefully solid castings of ecoflex 0-30 will do what I need. Bought it yesterday. They told me to use "silicone fluid" as a vehicle for the powdered pigments. I removed all the urethane film with paint thinner, which makes me feel much better about this.
Take it easy and thanks again!
 

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