Friday, April 05, 2013

Making a fake rock

Without a doubt the most boring prop I’ve ever made I think – at as far as descriptions go. There’s a short sequence in Moonshine of the Damned requiring some violence and a rock, so for safety’s sake we’re going fake

It was a pretty simple prop to make as well, finding the perfect rock was just as simple. It was in a pile by the car during a shoot last summer – so it wasn’t like I even had to hunt for one.

First thing I did was give it a bit of a cleaning. Most all of our rocks here are sandstone, not the easiest to clean – luckily this bad boy was granite – at least I think it’s granite, I’m not a geologist. Once it was all cleaned up I made a two part silicone mould – you’ll have to imagine that part, I didn’t take pictures because I didn’t think it’d be that interesting…and it might not be.

Once the mould was done I actually abandoned the prop once the web series was cancelled and only began thinking about it just recently. I had been making some other simple props and thought it was time to crank this out. It also helped that I finally had a handle on painting it.

It was easy enough to cast, but one thing to note about using Flex FoamIt, that I only found out last summer - I don't know how widespread this information is, but I didn't know this - the material, once cured, can sort of shrivel into itself, this can easily be fixed by crushing the piece, squeezing out supposed gases that cause the shriveling effect. So far it's worked well for me nearly 100% of the time.

So, here’s some pictures:

The mould, made of silicone with a support shell.
I bolted it together, seemed the simplest thing to do.
The original rock (left) and the unpainted soft foam rock (right).

The fake rock - the detailing is what helps it, even this doesn't look too bad.

 The original and the final fake rock. Didn't come out too bad.

And here it is, in all it's artifical geological glory. The Fake Rock.

So there you go, a fake rock. It's only needed in a very short sequence, but it's one of those thing that you might write in a script and not really think about how you'll accomplish it, let alone accomplish it safely. This is something I couldn't have done a couple years ago and now it's a completely simple process to create a tiny bit of movie magic.

Chances are when you see the scene it's in, you won't really think "How'd they do that?" Most people will just assume it was a trick camera angle, or some folks who don't really understand FX might even think it's CG - nope, it's a chunk of soft foam. It can be throw right at a person's head if needed and it'll be relatively safe - at least moreso than lobbing a real rock.

Technical Info: The whole thing was done using Smooth-On products. The mould was Rebound 25 with a Plasti-Paste II shell. The rock itself is made from Flex FoamIt V and painted using Monster Makers Latex Paint Base tinted with acrylic paints.

This isn't something I'll ever put on the website for sale, but if you've stumbled upon this and think it'd be a whole lot easier (since the mould is already made) to just buy one instead of making one yourself, feel free to send me an email. I reckon I'd sell it for about $25 - it's a bugger to paint decently and does take awhile. Email:

Note about cost: Just an FYI concerning the cost of making one of these. It's not too bad, but even using the minimum quantities available of the products, you're looking at over $100.

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