my sculpt (warning non guy stuff inside)

[glimmer]

I am not sure if this is the right place to post this and whether it is OT, but I figure its a bit like a bust, so... anyway, mods, please delete if it is OT.
I am trying to cast these parts in resin with silicon moulds. It is very time consuming and lots of trial and many errors... and I need lots of advice and help!

Here is the origional concept drawing

super sculpy start

baked and partly strung

all parts primed and standing on her own


First cast part



All parts are hollow to allow for stringing

[mangozac]

Wow that looks great Glimmer! Your sculpting is pretty good! Don't worry it's definitely not off topic - you're sculpting stuff and you want to cast it

Casting hollow parts is a pain - do you cut them all in half first?

[glimmer]

[img][img][/img][/img]Hi thanks I am glad I am not OT. Here are my most recent semi successful attempts to mould and cast the legs. Apart from the terrible bubbling (which after reading here I think I can reduce), they were ok.
I use a single part mould and a straw to make the legs hollow
the lower leg and the pvc pipe I use for mould plus plasticine
I make one cut in pvc pipe
and put a straw through so it will be hollow

sprue of plasticine and attempts at air vents (didnt work!)
Using pinkysil silicon - after it sets
cut the silicon and put in registration keys by cutting. note the straw (coated with release agent) through the top
then rubber bands and pour.

[mangozac]

Wow it looks like you already really know what you're doing! It should be relatively easy to get a part like a limb bubble free - you just have to be smart about vent placement

Have you tried pouring in one side and having a vent on the other side (both at the same end of the limb)? Also if you're getting bubbles stuck to bits of detail (like on the face) try dusting the mould with some talc - it prevents the bubbles from sticking.

[glimmer]

[paulson games]

You have some really nice work on the sculpting.


Couple questions to help get a feel for your casting.

Are you casting the resin under pressure?

How long is the working life and cure time for your resin?

Where are the bubbles occuring on your casts? Are they spaced throughout the piece or are they concentrated along the top edges of the cast?


If you are getting lots of bubbles along the top one possible issue might be that the parts need to be angled slightly in the mold so that the air all rises towards a vent (which should ideally be placed at the highest point), if the piece is posistioned relatively even then it generally will create flat spots that can trap air even if you have a number of vents in place.

If that's the case try tilting the mold slightly as you are pouring, holding it so one of the vents is at the high point of the mold. That should help air flow out easier without needing to remake the entire mold.

As Zac suggested a dusting of talc helps a lot as it helps break up any bubles on the surface of the cast and it never hurts to give the mold a series of light squeezings as that can help push air out as well. give a light squeeze let up on the pressure squeeze again, repeat a couple times and you should see some of the air bubbles work their way up as the resin gets sucked down into the air channel. Then top it off with a bit more resin.

The doll is a tough project to tackle as a first project, I've yet to do any single piece casts that are also hollow so everything I can suggest is mostly theory. It's certainly doable as I've seen lots of hollow doll parts at the craft stores.

[Munkey Joe]

This is just gorgeous..... Thanks for sharing.

[glimmer]

[paulson games]

Don't put too much pressure on the mold when you squeeze it, just enough that the mold flexes slightly. Any more than that you will potentially end up with spills or the mold can slip and the cast will have uneven edges.

Some people bang or tap their molds against the table, personally I think this causes a lot of splashing and mess.

When you dust with the talc you just want a fine coat, so brush some on and tap the mold against the table so all of the excess talc falls out and leaves you with only a light dusting. If you leave too much in it'll create small pockets in the resin which will be filled with talc.

Hopefully you'll get some improved results, let us know how it goes and we'll help figure out what is or isn't working.