Sculpting in hydrocal for vacuum forming project (a helmet)?

sohcahtoa

New Member
Hello anyone listening. I'm planning on making a very fitted robot helmet by lifecasting my head in two-parts (a front piece and a back piece) (with smooth on, plaster bandages, and hydrocal) and then sculpt around that (with a sculpting mixture of the hydrocal mixed with acryl 60). Then I plan to vacuum form that with PETG. And attach it all together with rivets and elastic bands.

Please note: I am sorry if this is not the right place to post something like this.
And another word of caution: I have no experience in prop making. My background is in clothing construction/sewing. But I have been researching and trying to learn things for a while now.

Here are two quick simplified sketches of my idea:
https://imgur.com/a/J9vic

It's a rather simple silhouette so I'm hoping it won't be too difficult of a project for a newbie. I've been watching sculpting videos on YouTube, but none of them work with Hydrocal. Should I use a different material to sculpt onto the hydrocal lifecast?

But another big obstacle for me is the vacuum forming. I'm not opposed to paying someone to do it at a shop... but I just want to be able to do this myself...
So, I want to make my own vacuum former, but I don't know how to deal with the heat source.
My oven is not big enough to fit large sheets (and I don't really want the fumes wafting around the house).
I've seen xrobot's DIY version with his 2,000 watt patio heater, but I'm from the U.S. and apparently our voltage is much weaker? From what I've read, the heat isn't strong enough or something.
So, I'm wondering if it could work if I rigged two 1,500 watt heaters, one on the top and one on the bottom of the plastic?
I dunno. Is there a better way?
I'll probably just end up paying someone at this point (hopefully I make decent enough sculptures/molds to get here).

Anyway... shoot me any advice/tips/criticisms (hopefully someone has any)...
Are there any problems that you see?
Problems that might arise?

Thanks.
 
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Hi
In first instance adding Hydrocal over Hydrocal should be fine, same materials. Usually it´s good to dampen the plaster surface before adding more plaster to ensure propper adhesion.
I guess you are adding acryl 60 to get a stronger plaster?...why not using Ultracal or similar then, instead of adding acryl 60?.
Another option could be sculpting with clay over the lifecast, mold it (silicone or waste mold) and cast it with ultracal or similar. Personaly I would preffer sculpting clay than carving plaster, but at the end it´s the result that counts.
 
Hey! Thanks for replying.

The Acryl 60 is because I saw a YouTube tutorial where someone used Acryl 60 with the Hydrocal to sculpt with.
I guess it's not really necessary if it's pretty much the same as Ultracal.

And yeah, you brought up my biggest predicament for the sculpting part. So I can't really sculpt with the Hydrocal/Ultracal, right? It'll be more like creating the base and then carving/sanding it down? Because the material is not viscous right? Hydrocal/Ultracal is quite runny? Does it not become "tackier" if it dries a little bit (like modelling clay)?

Thanks again.

-edit-
I found this thread https://www.therpf.com/showthread.php?t=13454 which pretty much answers my question
which links to http://www.tk560.com/phpBB2/viewtopic.php?t=635 which is also helpful (even though the pictures don't work)

I'll come back if I have further updates/questions.
I'll still take clay recommendations though.
 
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"So I can't really sculpt with the Hydrocal/Ultracal, right? It'll be more like creating the base and then carving/sanding it down? Because the material is not viscous right? Hydrocal/Ultracal is quite runny? Does it not become "tackier" if it dries a little bit (like modelling clay)?!

Well. you won´t be able to sculpt the same way you would do with clay, but you can build up shapes with it if you control the tempos: (liquid-cream-butter) of plaster. Actually this is done when creating a build-up mold. But of course there will be some carving/sanding at some moment to refine shapes etc...
All in all I would sculpt in clay over the lifecast, mold it, and vacuum with a plaster casting.. You can sculpt with cheap ole water based clay if you preffer, which is easier and faster to work with.
And if you mold in silicone you will have the chance to correct flaws etc...as you will b able to get more plaster pulls if you need to.
 
That could be one, looks like WED clay. It´s a slow drying clay. You might be able to find cheaper water based clays, if you are in U.S. take a look at Laguna Clay.
 
That is the right kind of clay but that price is crazy high. Not sure where in you're located in SoCal but LA has places where you can buy WED clay for about $10 for a 25lb block.

I agree that sculpting with hydrocal would be a nightmare. Clay is better. WED, of course, will dry out if you leave it too long. Lay damp paper towels over the sculpt to keep it wet if you take a break from sculpting. If you're a slow sculptor, then consider plasticene clay, which won't dry out. Ever. Probably a firmer one if you're going to be vacuum forming over it.

Also, consider ultracal over hydrocal. It's a bit more expensive but tends to be stronger and hold up to heat better.
 
That could be one, looks like WED clay. It´s a slow drying clay. You might be able to find cheaper water based clays, if you are in U.S. take a look at Laguna Clay.
Do you have any recommendations for which Laguna Clay to buy? They seem to have many different types...

That is the right kind of clay but that price is crazy high. Not sure where in you're located in SoCal but LA has places where you can buy WED clay for about $10 for a 25lb block.


I agree that sculpting with hydrocal would be a nightmare. Clay is better. WED, of course, will dry out if you leave it too long. Lay damp paper towels over the sculpt to keep it wet if you take a break from sculpting. If you're a slow sculptor, then consider plasticene clay, which won't dry out. Ever. Probably a firmer one if you're going to be vacuum forming over it.


Also, consider ultracal over hydrocal. It's a bit more expensive but tends to be stronger and hold up to heat better.
Could you recommend a firmer plasticine clay? I'm in Riverside, CA - not opposed to making a drive down to LA. Should I use silicone or alginate if I work with plasticine clay?

I see this one on Amazon https://www.amazon.com/Sargent-Art-...id=1519938670&sr=8-4&keywords=plasticine+clay

Thanks for all the help guys. I'm getting a better, solid, idea of how I'm gonna do everything!
 
Chavant nsp hard would probably work. I usually use the medium for most sculpting projects. If you come to LA, look into Nigel Beauty Emporium or Frend's Beauty Supply--they'll have the ultracal, the clay, plaster bandages...pretty much everything you need for lifecasting...and people to whom you can direct questions. Reynolds Advanced Materials is another good source.

As to silicone or alginate....are you talking for your lifecast? If I'm understanding correctly what you're intending, they wouldn't be coming in contact with the clay. But maybe I've misunderstood your process.
 
Chavant nsp hard would probably work. I usually use the medium for most sculpting projects. If you come to LA, look into Nigel Beauty Emporium or Frend's Beauty Supply--they'll have the ultracal, the clay, plaster bandages...pretty much everything you need for lifecasting...and people to whom you can direct questions. Reynolds Advanced Materials is another good source.

As to silicone or alginate....are you talking for your lifecast? If I'm understanding correctly what you're intending, they wouldn't be coming in contact with the clay. But maybe I've misunderstood your process.

Ah, yes, my initial plan was to vacuum form directly over the clay+plaster lifecast/sculpture
...but udog brought up the idea of making another lifecast of the clay sculpture and cast that again in plaster...

I'm probably going to try both methods... just to try it out and see what the results are like.
 
Ah, yes, my initial plan was to vacuum form directly over the clay+plaster lifecast/sculpture
...but udog brought up the idea of making another lifecast of the clay sculpture and cast that again in plaster...

I'm probably going to try both methods... just to try it out and see what the results are like.

Ahh, I see. I missed that. I would definitely use silicone to cast your sculpt. Alginate molds start to shrink when exposed to the air and you can get warping if you don't pour your cast right away...and you'll probably want to do a couple of layers to avoid thin spots--if you pick up some silicone paint, you can color each layer in contrasting colors in order to see where the silicone is thin (where you can see the color of the layer below).
 
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