Silicone hates me! why won't it CURE!!!!

[PearlieMae]

I use waxed paper and plastic coated freezer paper under everything and silicone cures right on top of it! If you make a resin mold, don't use latex then try to use silicone. While the resin doesn't absorb any of the latex, it's not glass smooth and micro-residue will adhere to the surface of the resin mold and you'll ruin your rubber.

To tell you the truth, I don't know why anyone uses latex. It doesn't seem that much cheaper, it smells, you have to do many thin layers, and some people have violent allergies to it. I would love to hear arguments for latex...in a separate thread!

[Taz]

This is a very good idea to be discussing this!

I used vaseline around the edges of my UltraCal mould for my scales, just in case the UltraCal and cardboard stuck together. After the Ultracal was hard, I removed the scales and wiped all the surfaces that had vaseline on it with a wet rag with a bit of dish soap. I was not extremely thorough, but still careful. Last night I poured my first Dragonskin scale sheet and it does not seem to have been affected by the vaseline. Keeping in mind however that very little Dragonskin was applied to the parts of the mould that had been in contact with vaseline.
I'll keep you guys updated if things change!

[Mermaid Julz]

PearlieMae, you beating up on my Latex!!! :P

[Anahita]

Once I used baking parchment on accident instead of waxed paper to cover my work area. (I wasn't thinking, all out of waxed paper, but with LOADS of parchment)

Don't do that, lol.

In case anyone's unfamiliar, baking parchment is silicone infused... Platinum silicone infused (to be food safe, obviously)

So when I tried to "glue" my two pieces of whatever the hell I was making together, I accidentally glued them to the paper.

[Atlantisblue]

If wood is unsafe to use with silicone, what do I place my scales on at the beginning as I start to create my mold? I have a wood board that was for the bottom of a crib that I was hoping to use...

[Elle]

it's some woods. but I'm not sure I understand what it is you're doing. If you're just using the wood for your mold, then I don't see and issue. If your using wood to cast from I'm very interested to see what you are doing

[Atlantisblue]

Oh I mean just a surface to place my clay scales on as I prepare my scale sheet for molding

[Elle]

it should be fine. Because you'll be taking the mold off the wooden surface and then pouring the silicone into your mold.

[PearlieMae]

I wouldn't use plywood, though. Who knows what they use to fuse the bits together!

Repeat after me...ALWAYS DO A TEST, FIRST. It's the Pearlie Mae Mantra.

[Sandra Siren]

Wow! Thanks for this list! I've been trying to make a fluke mold out of something other than caly, because my sculpting skills suck, and this has been super helpful to know what to avoid!

[LouLouBelle]

There's lots of good information in this thread.

I'm using Platsil Gel 10 which is easier to get in the uk compared to DragonSkin, and I get the impression it's not quite so sensitive when it comes to curing inhibition. I haven't ever used Dragon Skin though, so this is just be impression I've gotten.

I tested against Duck Tape (Duck brand) and it cured against both sides of it without any issues. It also cures fine against Vaseline. (I make a few shell/scale moulds using sea shells and silicone putty, and need a releasing agent otherwise the Platsil sticks to the moulds)

The only issue I ever had was when I tested against a flexible polyurethane. I couldn't find a list of ingredients, but it had a strong smell that made me think sulphur... And the silicone directly against it didn't cure.


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[gotwookiee]

Gel 10 is a faster setting silicone. It's been my understanding that fast setting silicones are less susceptible to cure inhibition in general. I don't think there is much time for other chemicals to cause problems.

I've used gel 10 to do some life casts against a latex bald caps without problems, though I did apply a layer of Vaseline first.
There are fast setting versions of Dragon skin, and Smooth-On sells an accelerant for their silicones. Heat will also accelerate cure time, so perhaps you could minimize cure inhibition issues with speed.

I've found the silicones from both Smooth-On (DragonSkin, Ecoflex, etc) and PolyTek (Gel-10) to be pretty similar. I've used each companies pigments and thickening agents with each other, and even Smooth-On's HyperFolic with Gel-10 and found them to be compatible. I've found that Gel-10 has a higher viscosity but other than that they seem to be the same.

I've never had cure inhibition issues with any of the silicones I've used, but I've followed other people's troubles on various forums, and wood is often the culprit. There are so many glues, vanishes, finishes, paints, etc that could be causing trouble.

I've also seen plaster/stone have problems because they are porous and have absorbed something silicone doesn't like. A number of years ago, a predator costumer had made a stone mold of a predator mask sculpt. He did a couple of latex pulls then tried to run a silicone skin, only to discover that the plaster mold had absorbed the sulphur from the latex and would not allow silicone to cure.

If you're having problems, use a process of elimination to determine the culprit. Is it failing to cure in the bucket? If so, then it's your bucket or the mixing stick or something else at that stage.
Make sure your mixing it thoroughly. If you're having trouble consider getting mixing attachment for a power drill.
If it's on the sculpt then take a sample of each material aside and test a little silicone on it and see what happens. One of those tests will tell you what the problem is.

And don't forget you can call smooth on for help.

The bottom line is don't be intimidated by silicone. In many ways it is easier to work with than latex.

[Mermaid Alaria]

Does anyone have experience with curing silicone on a polyester resin/ fibre-reinforced polymer?

[gotwookiee]

Does anyone have experience with curing silicone on a polyester resin/ fibre-reinforced polymer?

Do you mean like the kind used in fiberglass molds? My Chewbacca mask mold was a polyster resin fiberglass mold. Never had any issues with platinum cure silicones curing in them including ecoflex, dragonskin, and gel-10.

[Mermaid Alaria]

It's a textured board I want to use for casting part of my tail. It is a type of fiberglass I believe. Good to know. I'm certainly planning to test.

[KernowMermaid]

I've had a curing issue and I can't figure out why! I was doing a touch up on the paint, I used the same pots the same pigment and was careful when mixing it I used a new brush from the same pack I'd used the others from and painted it straight onto the tail. For some reason it hasn't cured at all and its so confusing I had basically finished the ta and I need it an a few days time....it's a complete disaster. Is there a way of fixing it?

[Mermaid Wesley]

I've had a curing issue and I can't figure out why! I was doing a touch up on the paint, I used the same pots the same pigment and was careful when mixing it I used a new brush from the same pack I'd used the others from and painted it straight onto the tail. For some reason it hasn't cured at all and its so confusing I had basically finished the ta and I need it an a few days time....it's a complete disaster. Is there a way of fixing it?

you will have to clean all the uncured stuff off. try using paint thinner to get off the residue. and good luck!

[merwandering]

Wait- I thought you could have extra A but not extra B?
I havent had any curing issues (knock on wood) and I always measure in two cups next to each other, so its close but never exact of course- but I always pour the B into the A so that there is a little more A, since a little B coats the cup it was in...

[JanessaLuna]

Is this true that you can have slightly more part A? Or do you not want any more of less of either part? Good idea pouring it into the part A cup of this is true.

[parisfrantz]

Did the vaseline mess it up?