by cornixt » Thursday October 22nd, 2020 1:56pm
Here is what I wrote about blue stuff on another forum:
I've been playing around with this mould-making material called blue stuff that is sold by Greenstuffworld. There doesn't seem to be much discussion of it on the web, just a few videos. There is a Japanese brand of the same stuff that you can supposedly get at Walmart, which is sold as a toy for shaping little models from it, rather than as a mould. I've had blue stuff a couple of weeks so here is my impression of it so far (pun intended).
The website of Greenstuffworld does not make it clear how much you get. I bought the 8g box. The 4g box would make a single two-part mould for something the size of a 32mm model. It's completely reusable, so once you are finished with a mould you can just reheat it in boiling water and make a new one. It's cheap too, much cheaper than a resin casting kit. But the moulds it makes are not as high quality and are a little more limited in scope since you have to push greenstuff into every part. You can only use hot water to heat it up (if it was microwavable then it would be awesome), and when it cools it maintains its shape but has the characteristics of rubber.
It needs to be really hot to be good enough to make a decent mould. I have to make sure I stick it in just-boiled water or it remains too rubbery to pick up all the detail. Even after a few minutes of sitting, the hot water is no longer good enough. Rubbery-ness is the enemy of making a mould since you lose hard definition. This means that the mould has to be made just seconds after you pull it out, waiting too long gives you a crappy mould. After a bit of experience, you'll notice straight away and can just reheat and redo.
You can use painted models to make a mould, not even varnished, no problem. The blue stuff just peels off it nicely when hardened. I've used several different model types to make moulds - white metal, Reaper Bones, styrene plastic, greenstuff. Not found any that don't work yet.
For a simple press mould, you can use any modelling material that you can remove without deforming too much. Some stuff can get stuck and will stretch and pull as you twist the mould to get it out. I plan to experiment with Sculpey/Fimo to see if I can stop this - maybe line the mould with vaseline first. Hopefully it will work since my main aim is to make dungeon tiles with cheap Sculpey.
If making a two-half mould, make sure that the first half of the mould has cooled before you make the second half. Otherwise, the second half will stick to the first half and you'll have to cut them apart. You can only use self-hardening clays, something that needs to be baked will not work since you can't bake the mould. Fill both halves of the mould with green stuff or similar, then press them together and leave until fully hardened.
Don't overfill the mould halves with green stuff or it creates a thick mould line and the model isn't quite the right shape. This can be hard to judge, since the rubbery-ness of the making the mould can create a soft/curved edge making it unclear where to stop filling. It's very tempting to overfill, but it creates a deformed model that doesn't look good, while an underfilled model is still pretty much the right shape but just needs a few gaps filled.
You can fit an armature inside if you are careful before fitting the two halves of the mould together.
This is where I see you thinking you could make (i.e. copy) a whole army this way. I guess you could, although the mould lines on everything I have made so far are much more visible than anything on a bought model. I would have to find a greenstuff alternative that is better at being filed down. I wouldn't recommend it either, especially if you playing at a GW store since it is obvious to anyone picking it up that it is not made from resin, plastic, or metal. It could pass easily for a Reaper Bones model when painted.