Latex Mask Making: how do I preserve detail and patch a cracked mould?


Sorry if this is not the correct place to post this. I'm looking for some advice on: 

1) What to use (and how) to patch a concrete mould to reconstruct pieces that have broken in the course of setting and then cracking it open;

2) How to reduce the odds of cracks, do a better job at capturing detail and making sure that a mould won't break when filling in tricky areas like a mouth full of teeth. 

This is my first attempt at mask making, largely following the instructions in the guide by Monster Makers, here:

I sculpted this Skeksis-looking creature: 

I then made a concrete mould using Herculite (I'm from the UK, so I used Herculite as a the best alternative I could find to the recommended Ultra Cal). I added strips of burlap to strengthen it:

And wound up with a basic 2 piece concrete mould: 

Unfortunately, there were some pretty big cracks. In particular, the sculpt tore out the concrete around the mouth when I cracked the mould open. Here you can see just how much it took with it:  

So my question is: 

- how do I avoid having this happen again? (It's probably something pretty obvious, but since this is my first attempt I thought I'd better just ask). 


- can I use polyfilla to patch the cracks? I'd like to use something that I can sculpt a little before it dries. 

Best Answer


  • Thanks. Would a detail layer of silicone work with latex? Doesn't the latex have to react with the concrete? So if I used silicone, it wouldn't work? 

    As far as the second solution goes, I think you're right and I'm pretty sure it would have helped. I should have melted or softened the sculpture - the teeth in particular just ripped some of the more fragile plaster off when I removed it. 

    What would be a good way to heat it? It's huge - head sized, basically. I don't have a big enough oven to fit it into and I don't think I can fit it on top of the hob either. I could get a heat gun, I guess, but using a hair dryer on Monsterclay has never heated more than just the top layer. 

  • Hi Gareth.
    I think you are getting a little confused here. The silicone used is only to capture the details. in negative.. of your finished work. From there you can paint latex in to the silicone to create a positive latex skin. 
    The reason for using a flexible skin against your master is firstly it can pick up the very fine details (hair, wrinkles) and secondly you can carefully pull it around area's like ears and horns.

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