Mold making question...advice needed.

[ssdesigner]

A co-worker of mine is looking make a rather large mold of this "fortune-teller" sculpt he did using oil based (has sulfer in it) clay. The dimensions are approx. 22" tall x 19" wide. The castings will be made of paper mache and he will only need 5-6 of them total. In your opinion, what would be the best material to make the mold from, and what style of mold would you go with?

Thanks in advance!!



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-Ss

 

[Rhett J Martin]

Well, with the clay having a bit of sulfer in it, most folk agree that a few coats of primer will solve that, but be sure to get it completely covered.

As you most likely know, sulfer will prevent curing on some silcones.

I'd probably do a simple jacket mold, maybe something like Rebound 25 with some Plasti Paste over top for strength. Should dothe trick nicely.

If he wantsthe final prop to be light and farily disposable, an expanding foam should work great. Maybe something like Foam It X which I've used recently, and has a decent ability to capture detail.

**I should note, these are all Smooth On products, as that stuff is my favorite.**

I'd hate to see all that detail go to waste! It's a nice sculpt!

 

[ssdesigner]

So if the castings are to be paper-mache, will he have any difficulty getting the mache to cure with the silicone mold??

What type of primer have you had luck with? Just a krylon spray can type?

-Ss

 

[Rhett J Martin]

Not sure about paper mache, never cast with it . . .

But yea, any decent primer will work fine.

 

[coofunkcurly]

A silicone mold seems like overkill for a half dozen papier mâché castings. Casting in papier mâché also seems a bit of a shame because I cannot imagine it getting much of the fine details of this beautiful sculpt.

Is the cost the reason for going papier mâché? If so I would imagine he'd want to keep the cost of the mold down too. Maybe a plaster mold? Maybe have to seal it. Probably need a real good release too.

Sorry I don't have firm answers. Just throwing some out for discussion.

 

[ssdesigner]

These are going to be replicas of the old fortune teller booths from the 20's/30's. The originals were a paper mache, so the purchaser wants these pulls to be as well.

-Ss

 

[clonesix]

Hydrostone mold. No silicone needed for paper mache. The gypsum will soak in the water from the paper for drying.

My only concern is the amount of undercut. If he can flex the casting a bit as it is pulled out, there should be no problem.

 

[Stormrider]

I wouldnt use rebound 25. its platinum. And even with the primer, your likely to get spots where it doesnt cure.

Alumilite HS2 or HS3 is as durable as rebound 25, and its a tin cure. So it will cure almost anywhere.

Theres also quite a few free tutorials on their site for making the mold. They are super helpfull on the phone also, if you want to call them.

If you have used smoothon tin cures, smoothon is nothing like that. They last forever in your libraries, and dont tear like oomoo etc.

I highly recommend it.

 

[exoray]

I wouldnt use rebound 25. its platinum.

Stay far away from ANY platinum cure for this, they are way too temperamental with sulfur...

You might consider a thin glove latex or urethane mold, with a harder fiberglass or plaster mother mold to hold it all in shape... A plaster mold would be the cheapest alternative but I fear for the undercuts...

 

[vaderman1701]

Mold Max Stroke is Smooth-on's tin based brush on silicone. Good stuff.

Scott

 

[Rhett J Martin]

Ohhhhh!!! You WANT them to be paper mache!

Gothca . . cool idea!! Hope we'll get to see the results!

Hydrastone is the way to go!! Best of luck!!

Scott, I totally forgot about that new stuff! Gotta give it a shot when the new proton pack master's done!

 

[Abzilla89]

I'm with exoray. If the paper mache castings will flex enough, go with a gypsum mold...if the undercuts are a problem you may just want to go with a urethane mold even.

 

[Stormrider]

Urithane should be a lot cheaper than silicone. Thats definitally a bonus

 

[micdavis]

I think you are asking a lot of paper mache to pick-up that level of detail. GREAT SCULPT.

Even with a silicone mold, the geometry of the sculpt is going to create a lot of catch points in the mold.

 

[robstyle]

This may sound crazy and difficult but you may want to look at doing that in a three part hydrocal mold. I would suggest doing the arms and the main chest as sections so you can get the undercuts out of the mold without destroying the part. Take your time in molding, make tight and secure keys, back the hydrocal with burlap and do layers... The more proper time spent with the mold the less clean up youll have to deal with.

If you have no primer, you can always crystal clear the clay to seal it.

 

[MustangGTR1]

Use Smooth-on's SuperSeal on the clay,then use thier paintable rtv as well. They also make a resin that is thick to use as a mother-mold as well.

To get the detail, you need to use the paper that is more like a dust, the type they shot in walls when building a house...Kev