Has anybody cast anything out of expanding foam? (1 Viewer)

[Gideon]

I'd like to try and make something on the large size. It would need to be cast in some part to assemble.

Any ideas? Experiences?

 

[Captkronos]

I've done a couple of life sized busts out of it, but generally used it as an armature I carved down to rough size, then covered with air-harden clay, then cast a silicon mold around that. Some types of silicon bond to every little hole in that stuff if you have to carve it, and it can end up an expensive mountain of yuck. Are you meaning that you are carving your piece out of the foam, or making the mold with the foam?

 

[Somerset]

Hi Gideon,

I haven't cast with it yet. The people from whom I buy mold material had their "foam expert" call me to explain the properties of their different foams. I would suggest that you contact them: BJB Enterprises, 714-734-8929, www.bjbenterprises.com .

The main thing is adapting your mold to accommodate the expansion of the foam. This is particularly tricky with the lighter weight foams. According to the consultant, if you want good density and detail, you have to be able to fill the mold quickly and then seal it quickly. The mold has to contain most of the expansion while allowing enough excess foam to escape so that the mold, mold casing or containment armature aren't damaged. I was quite surprised at the amount of force some of the foams are able to generate during expansion. They also provided me with sample blocks of the different foams so that I could get an idea of the density and weight of each, (with the caveat that this will vary with the degree of containment that you are able to apply).

I hope that this is helpful.

Good luck,

Ron

 

[Gideon]

Thanks much! I would carve the model out of something else to create the mold with, carve channels to release the excess, trim and sand the flak.

I just don't anything about silicon molds and these foams, which type to use, etc.

 

[theBaron]

You might want to check with Matt Murphy of Hobby Bunker, if you want to cast the object out of expanding foam. If I'm not mistaken, HB's line of buildings is cast from a expaning resin foam, which gives a light-weight but strong casting.

I think Ken from All the King's Men also uses foam buildings, you might want to check with him.

Both are members of the forum, too, so I'd send them a couple of PMs.

Personally, I've never used an expanding foam for casting, only metal.

Prost!
Brad