First time sculpting / maybe casting latex mask (Korg)

[Hannoc]

Hi All,

I've lurked around this site for years enjoying all the amazing work done in all the different sections, I haven't really done much of anything myself aside from 3D printing, finishing and painting a Shoretrooper helmet which I really had fun doing.
One thing that has always interested my is sculpting but I've never got around to trying.
I really loved Korg from Thor Ragnarok and I thought what awesome character to go as for halloween this year but after seeing I couldn't find any mask available I thought why not try this sculpting thing.
To be honest I'm not expecting much and I may not even make it to the casting stage but what heck.
So I started with a 3D printed scan of my head filled with plaster as my base and have been playing with monster clay for the last few days, I know its rough,not accurate and still needs a lot of work but I've been having a lot of fun.










I have a couple of questions for if make it to the mask making stage,

1. Is plaster of Paris strong enough for a mold? (I can't get hydrocal locally and shipping is $$$)
2. Is there an alternative to water based clay for the mould wall as I'm having trouble finding that locally too?

 

[Buliwif]

Hi there! looking good so far. Plaster of Paris is strong enough for mold making, but it has a tendency to shrink over time. That's why Hydrocal and Ultracal are so often preferred, because of the marginal amount of shrinkage. There are alternatives to water based clay for mold walls, like thin metal shims that can be pressed into the clay and form a mold wall with minimal damage to the sculpt.

Laguna clay's WED clay is available on Amazon and it's relatively inexpensive (50lbs for less than 30 dollars)

Ultracal 30 is also available on Amazon and it's quite a bit cheaper than Hydrocal... It has a much longer life than plaster but isn't as absorbent as Hydrocal... but that shouldn't have much effect on slip casting... Ultracal also sticks well to itself, so if you don't mix up enough, you can mix up more and add more layers without fear of them flaking off... I've heard Hydrocal doesn't layer as well... It may have improved over the years though, I couldn't say...

One tip... adding strips of burlap to your mold will make it much stronger

 

[ChickenHaunt]

Generally plasters actually expand, rather than shrink. And it's not an issue of change over time so much as a part of the chemical reaction that sets it. The primary issue with Plaster of Paris is it's a very weak plaster. Hydrocal is a bit stronger, and Ultracal is stronger still (though Ultracal is technically not a plaster...science or whatever). Pottery Plaster is also a popular choice for production molds for latex masks. Similar to Hydrocal. You can use Plaster of Paris if that's all you can get your hands on. Just know the mold will start to degrade within a few pulls. Honestly, for your first mask, that's probably fine. Take care to follow the directions for the strongest mix. The burlap in layers after the surface coat is a good idea.

You can use an oil based clay for the mold wall. Water based is just easier. If you have a ceramics place near you, they may have a lead on some water based clay and some good plasters.

That said, check Frends Beauty and Motion Picture FX Company. These are LA supply places that I believe have worked out a system for shipping plaster.

 

[13doctorwho]

I really like it! I love that character.

 

[Buliwif]

I forgot to add in my initial post, I have used Plaster of Paris in the past for latex masks, and if you're not planning on making more than a few pulls it should be fine. To clarify, the shrinkage I referred to occurs over time and is minimal, but could be an issue if your mask is very close fitting (this is strictly speaking from experience, mind you, the apparent shrinkage could be a function of the mold expanding, I suppose the effect would be the same) but like I said, if you're just molding to pull a couple of latex masks you should be fine.

 

[Hannoc]

Thanks for the input everyone I really appreciate it,
I haven't had a chance sculpt anymore or to get online as I've been enjoying some camping the last few days.
I live in Canada and unfortunately amazon.com won't ship Hydrocal or Ultracal here and amazon.ca doesn't seem to have it. I can source it from some canadian suppliers online but the shipping cost is understandable expensive.
I have found a place in Calgary that does sell Laguna clay's but the don't have WED clay on their website but next time Im in the city I drop in and have a chat wand see if they can order in some WED clay or see if they have a suitable alternative and maybe point me in the direction of some hydrocal or ultracal, If I don't have luck I'll try plaster of Paris and burlap as its available locally and hopefully I'll only need to make 1 or 2 masks.
But for now I'm going to keep working on the sculpt.

 

[ChickenHaunt]

EM210 White Clay from Laguna is actually your ideal mold making clay. WED is more for sculpting. But you could probably make anything work. I think the main thing here is to try to find the good stuff, but don't let it get in your way if you can't. Pretty much all these materials were originally developed for other industries and purposes, anyway. People have just figured out that they tend to work well for what we do, and people in other regions have found local versions that do the job well, too.