Cleaning sulfur based clay out of Ultracal mold?

[Egon Spengler]

So I bought Amaco clay from Hobby Lobby to sculpt my mask. I was not aware until I found a topic on here that the clay contains a low amount of sulfur. What I hope you can all help me with is the following.

If I use Acetone or Naptha to clean out the clay, will the fact that the clay was in the Ultracal mold still give me issues after cleaning it out ?

Also would sealing the inside of the ultracal mold with something help? If so, what do I use to seal it? Shellac? Krylon Crystal Clear?


I really hope this isn't going to be a massive issue to fix.


Thanks!

 

[udog]

Ultracal is fairly porous (less than normal plaster, but it is) so most probably it absorbs inhibitors like sulphur.
Clean your mold, first with IPA (isopropilic alcohol 99%), then you could give a go with naphta. Not sure about acetone. Clean thoroughly, several times.
There are two products that could help:
Inhibit X

Inhibit X Available in the US and Canada - Reynolds Advanced Materials

www.reynoldsam.com

Read well the tech sheet. It says you should also use a release (Ease Release 200 spray for example). I have ever used this one, looks interesting.
The other one is Bond Fx.

Support Products | Fusefx

www.fusefx.ca

This one, I have used it some time ago. It does build up a little but I have been able to get plat silicone castings out of small tin silicone molds, some times a bit tacky.
Maybe sealing it prior to applying any of these products, with Crystal Clear could help to create a better barrier. Never tried that either.
Both are expensive products.
It is an important issue. I would make small tests in an uncompromised area of the mold, such as the back neck part to make sure before pouring expensive ecoflex in.
Ecoflex 00-30 is a slow setting silicone. This means the silicone has more time to pick up inhibitor contamination. Fast setting silicones are less susceptible to inhibition. They inhibit with sulphur too as any other platinum silicone, but if inhibitors are slight there are less chances (or the inhibition will be slighter) than with a slow setting one.
So Ecoflex 00-35 Fast could be a better option in this case.

Ecoflex™ 00-35 FAST Product Information

Skin Safe, Fast Setting Super Soft Silicone

www.smooth-on.com

The problem you will have to face with 00-35 is the short pot life it has. It could catch you pouring it. You will have to look for a way to make it fast (bigger pouring area) or inject it.
The only way you will know is testing (small tests) and trying all this. If you can test with both 00-30 and 00-35 it wold be great. If it worked with 00-30 you would skip the pot life issue, wich is important.

 

[Egon Spengler]

Thanks again for your help! Im going to attempt to clean it several times over and seal it like you said. I might just for experimental purposes mix up a small bit of the Dragonskin FX I have and pour it into a little sculpted bowl of the clay I have that I'm going to seal. More than likely it'll cure badly but I want to see how "little sulfur content" will effect it. If

 

[udog]

Thanks again for your help! Im going to attempt to clean it several times over and seal it like you said. I might just for experimental purposes mix up a small bit of the Dragonskin FX I have and pour it into a little sculpted bowl of the clay I have that I'm going to seal. More thsn likely it'll cure badly but I want to see how "little sulfur content" will effect it.

Well, obviously it will be worse in the clay than in the cleaned mold.

 

[Egon Spengler]

Well, obviously it will be worse in the clay than in the cleaned mold.

Well, I had the old Dragonskin FX sitting around as I said and decided to mix it up and put it straight into the front mold and back half. I am VERY relieved and happy to say IT CURED! I even put it right down over some of the dried up clay that was still in a part of the mold. I didn't seal ANYTHING. Of course the dried clay stuck into the silicone because of that, but nothing came out gooey or sticky. What a massive relief. So so far it seems like the Hobby Lobby clay by AMACO, if it does have sulfur in it, has "very little" as they said in the info I found.

I can't tell you what a massive relief this is. Thank you so very much Udog for all your help answering about this. I'm glad I don't really need to get into all that, but it's good advice for anyone that might find this topic that is concerned about having issues with silicone.

Dragonskin does cure faster than Ecoflex. so maybe thats why there was no issue? But I'm going to get some Ecoflex and we'll see how a small batch of that mixed up goes. I think it might just work out either way.

 

[udog]

Good news then, yes, getting into inhibition issues can be a pain in the neck...or somewhere else.

Dragonskin does cure faster than Ecoflex. so maybe thats why there was no issue?

Ecoflex will be more sensitive. But if you got a fine cured silicone that means that there´s very little sulphur or non at all. Any tackiness in the test?.
Some tackiness could mean there´s something bugging around (totally cured silicone has no tack at all). But all in all if it didn`t turn into a gooey silicone soup or similar I think you will be able to manage it even if there´s a slight tack.
Test the ecoflex first anyway.
And something that could help too (if there´s any problem like tackyness), is to heat a little the mold and the product (don´t over do it, just that it´s tempered with hair dryer or similar). That will aid to speed up things a little and might help to avoid any slight inhibition that there could be. If you heat it too much it might kick too fast, and that means less time for the silicone to let air bubbles out, specially if you are pouring.
Platinum silicone speeds up with heat, all of them.

 

[Egon Spengler]

Good news then, yes, getting into inhibition issues can be a pain in the neck...or somewhere else.

Ecoflex will be more sensitive. But if you got a fine cured silicone that means that there´s very little sulphur or non at all. Any tackiness in the test?.
Some tackiness could mean there´s something bugging around (totally cured silicone has no tack at all). But all in all if it didn`t turn into a gooey silicone soup or similar I think you will be able to manage it even if there´s a slight tack.
Test the ecoflex first anyway.
And something that could help too (if there´s any problem like tackyness), is to heat a little the mold and the product (don´t over do it, just that it´s tempered with hair dryer or similar). That will aid to speed up things a little and might help to avoid any slight inhibition that there could be. If you heat it too much it might kick too fast, and that means less time for the silicone to let air bubbles out, specially if you are pouring.
Platinum silicone speeds up with heat, all of them.

No tackiness at all from what I've felt, which is a big relief. If the Ecoflex doesn't work the Dragonskin will at least. I have to say, everytime I type in Dragonskin my fingers almost always want to type Dragoncon. Just a side note I still have a lot of cleaning out of clay to do but I think it's going to work out. I might break out the hairdryer for ecoflex

 

[udog]

Ok, no tackiness should mean no problem in first instance.
The best is a small test first. If tackiness appears, go for the heat.
I think you should be ok with this.