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Hello guys,
I'd like to cast a couple of heads copying a resin figure's head to replace crappy Tamiya ones using Instant mould and green stuff.
I've never done this before and I'm not sure how to start? How would you recommend I mould them? Front of face and back in two halves? Blob the mould over the whole head and slice it of? I'd obviously like as little clean up as possible. How do you guys do it? Any suggestions greatly appreciated
Cheers, Martin

Slicing a mold in two is likely to result in a finer seam, if the shape is conducive to it. Something with lots of ridges and texture (hair, etc.) makes it hard to cleanly slice through everything, resulting is jagged tears in the recesses that the blade missed.

As for where to part your mold, whether by cutting or applying two halves, it depends entirely on the part's shape. Some work best front to back, others side to side. Some really oddball helmeted heads might even work better top to bottom. If you know where the original parting line was, that's likely to be your best bet for a copy.

Check out the Hirst Arts page on the subject. Bruce does a good, if simple job of explaining different mold making techniques without some form of degassing set up.

Cheers guys,
I'll check out that link and then have a play around with the moulding.

Blob it over the whole head and then slice it off. I've done this with a few different models over the years - including about half way down the first page of this - http://www.dakkadakka.com/dakkaforum/posts/list/0/346076.page

Insta-mold, when cured, is flexible but very structurally tough. I'd usually blob it over the head and shoulders, then just pull it off - or, if necessary, make a knife incision along one side to make a bit of space before you pull it off.

The knife incision should close up again really tight, but if it doesn't then you can hold the mold together with rubber bands - because the cured insta-mold is so tough you can apply a fair amount of pressure without warping the result.

I started with green stuff, which is fine, but two-part resin gives a better result. Two part resin can get quite messy, though!

If you are not interested in saving the piece being molded, then cutting off the mold is a better option (as you can then cut straight into the molded part).

MB

BeAfraid wrote:
If you are not interested in saving the piece being molded, then cutting off the mold is a better option (as you can then cut straight into the molded part).

MB

That's true and will probably work out best but I need to save the original really. I can't trust my abilities to get a good copy and then I'd have lost the original too!
That's why I've asked the question, I've been scratching my head trying to work out the best way to cast from it and save it. Cheers

Honestly I'd try recasting the entire model and chopping the head off the recast to create the mold. This way if you damage the model in the removal of the head it doesn't matter since you still have the original.

 ArbitorIan wrote:
Blob it over the whole head and then slice it off. I've done this with a few different models over the years - including about half way down the first page of this - http://www.dakkadakka.com/dakkaforum/posts/list/0/346076.page

Insta-mold, when cured, is flexible but very structurally tough. I'd usually blob it over the head and shoulders, then just pull it off - or, if necessary, make a knife incision along one side to make a bit of space before you pull it off.

The knife incision should close up again really tight, but if it doesn't then you can hold the mold together with rubber bands - because the cured insta-mold is so tough you can apply a fair amount of pressure without warping the result.

I started with green stuff, which is fine, but two-part resin gives a better result. Two part resin can get quite messy, though!

That's great, just what I was after. Your results look amazing! I was worried about getting the original head out of the mould but looking at your pics it doesn't seem that scary now!
Thanks for that!