Casting something that is foam latex

[patsmear]

Hey all, if i was going to cast a foam latex appliance, can I just use plaster? I don't want to ruin the original. I need a latex version so I can have a "Hard Copy"

Any other ideas?

 

[Deathstalker II]

I've found that the best way to cast an existing appliance is to use alginate - just like you did to make the positive on which the appliance itself was sculpted. Alginate doesn't evenstick to itself (so it doesn't stick to latex), and crumbles when it dries - leaving residue you can remove with a sponge.

I don't know what kind of appliance this is - something you made/something made for you/replica/screen used - but if you can, I would recommend applying it to whatever it's supposed to be applied to, then doing an alginate cast of the application and outlying area - this will help it keep shape. If it's a facial appliance made for an actor - you would apply it to the lifecast of the actor (or a close approximation - something to help it keep its original form), then cast that in alginate.

You definitely don't want to use plaster...

 

[patsmear]

So I would have to do alginate, the run a plaster positive, then try to back to latex from there?


If it comes from a plaster mold, why would it be bad to use plaster to remold it?

 

[SonOfPumpkinhead]

The plaster may seep into the pores on the foam and tear it up or mess with the surface... I have heard of getting latex castings out of alginate if the alginate works... There's always silicone as well. You could also do an alginate or silicone mold of the piece and then do a clay pour and correct any flaws, alter/fix details, etc. and THEN mold that in plaster for the latex versions.

 

[patsmear]

I have tried clay into alginate and not had good results. I guess silicone is the way to go....of course!

Thanks for your answers both of you!

 

[SonOfPumpkinhead]

did you dry out the alginate with a hair dryer or heat gun and then melt oil clay to a liquid consistancy? I've also heard of people drying it out and really pressing wet clay into it. The clay pour seems more practical though. Either way, you can use alginate, it just has to be dried out. If it's too wet the wet clay won't get any detail as it'll be washed out and if you use oil clay in a wet alginate mold, well, oil and water don't mix... You just have to be careful not to dry it to the point that it starts to shrink and crack. Just enough to get rid of the moisture.

 

[Deathstalker II]

b89 - the only reason I didn't consider silicone is because I had no idea if the silicone would react to any paint, make-up, or adhesives that may have previously been used on the piece. But I think you're totally right about alginate on oil-based clay. That should work.

Patsmear - am I right to assume that this appliance is something of significance you're trying to retask? Because I feel like going to alginate (or silicone, for that matter)...to plaster positive...then back to foam would allow you the opportunity to retool the original to work with the new wearer, and to fix any resultant flaws in the piece itself or its blending edges.

 

[Eaglewood]

I use alginate a LOT and recently did a new mold for one of my pieces--the only reason I used the alginate is because I was out of silicone. Unless the piece has not undercuts and can be flexed a bit--I dont recommend the alginate--My piece was a gypsum based material that had been painted and the alginate stuck like glue to it-- Luckily it didnt ruin the piece. I switched to some silicone and no worries at all there.
If you use the alginate do a small test areas first!
Just a word of warning.
Good luck.

 

[Deathstalker II]

He said this was a foam latex appliance - so I'm thinking that's non-rigid, skinned, and not gypsum based. He should be fine.