Hollow statues, how?

Spazzy · 05-01-2011, 11:52 AM

Ok, so I am new to sculpting and casting, and from everything I read the casted piece needs to be solid for the pour, but after having to break a few statues as a replacement from Sideshow I noticed even small pieces were hollow, how do they achieve this? links? I really can't figure out how they do it, and am very curious, as it would definitely save some resin when casting....not that I would risk if it is too difficult though.
Thanks!

riteguytu · 05-01-2011, 01:48 PM

Its called Rotational Casting or Roto-casting or Slush casting. Basically there's a machine that spins the casting material within the mold until it hardens. You'll then get a hollow piece due to centrifugal force...

Spazzy · 05-01-2011, 06:04 PM

ah, makes sense, thanks!

Guess I will be making solid casts.

Spazzy · 05-02-2011, 01:12 AM

saw one of these machines, really cool, but around $4000! yikes, be awhile before I can get that.

**Vince-Vell** · 05-02-2011, 09:26 AM

some statues have balloons or air pockets put inside them so you save on resin and or not being to heavy

Take a statue of a big hulk and its casted in 4-5 pieces. If you are casting up his torso as a section, you can place a long block of plastic into it. So when the cast is done you pull that plastic piece out and the whole section between his stomach and back is hollow going up to his shoulder blades.

So since statues are casted in pieces and then put together, this picture can give you a idea on how to create a hollow cast without having to roto cast it. Now im sure if a hulk statue torso is cut off once the sculpt is done, you can carve out the inside of the statue a bit so when you make a molding its more or less hollow once poured.

Spazzy · 05-02-2011, 01:16 PM

Awesome, great idea, I will have to try that when I get a bit more skilled, and wouldn't mind experimenting.

NIMAJNEB · 05-02-2011, 01:36 PM

you also could do a roto-casting by hand !
If you are using a fast curing PU resin (3-4 min).

Pour a small quantity of resin inside your mould. Block the pour hole with something (or your thumb if it's not too big) and moved the mold in every direction without stopping until the resin have hardened. Repeat the operation 2 or 3 times until you have a small thickness of resin almost everywhere.

it's done !

you can also fill it with something cheaper like plaster.

if you are using a 2 parts mold and polyester resin you can use fibreglass and make it hollow too with laminated technique (but it works better with big sculpture)

Spazzy · 05-02-2011, 01:51 PM

I figured I could do a roto casting by hand, but it would take 10-15 min, I have a resin that I believe is 10-15 min cure, would tire out quick lol.

What about the possible air bubbles of not getting into all the cracks and crevices? does the motion get the resin in there? Or as long as it is gated correctly it should be fine? I know I got to test but if I can save a few bucks in the process, great!

Alaneye · 05-03-2011, 04:23 PM

Use a low viscosity, fast cure resin, and talc the mould. Shake some talc, even baby talc, into the mould then pat and blow out all the excess so that there is a very light dusting of talc in the mould. Then when you pour, the talc draws the resin into all the detail. You could also lay the mould open and brush the resin into the detail before closing the mould, then pour more resin in and do the hand roto casting. I've used the method my self, it works. With a low viscosity resin, your mould needs to be tight, or the resin will pour out between the seam line... but that also depends on the weight of resin being pored into the mould.

Al

Spazzy · 05-03-2011, 07:30 PM

I use the resin from dascar plastics, saw them on ebay http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT

says very low viscosity.

I always knew to put talc in it, but thought that is more for the release, good to know that it helps move the resin to where it needs to be.

Thanks AL!