I'm based in the UK and am looking for an alternative for the epoxical Bruce Spaulding Fuller used in his character makeup series to make moulds with the ultracal and burlap. If anyone knew of something I could use it would be much appreciated.
I haven't formulated a specific recipe for molds yet, but basically all epoxy products you can replicate for cheaper (and easier supply often) by buying epoxy resin, that would be between 20 and 30€ per liter (definitely less than specialty epoxy based materials), and adding other ingredients to change the characteristics (and lower the price since the other stuff is all much cheaper, all I'm suggesting is less than 4-5€/kg). The stuff you would need to formulate your own recipe is basically just this: 1- calcium carbonate (meudon white), inert fine powder, just a very fine filler, quite cheap, tends to thicken the resin 2- wood flour, extremely cheap, not fine enough for the detail layer, tends to thicken the resin, makes it extremely hard and reduces the tendency epoxy has to gum up sandpaper, it is used to make putty for modern wood boats for instance 3- amorphous colloidal silica (crystalline version is carcinogenic), this is the famous cab-o-sil Americans always refer to, it makes anything thixotropic, it's cheap and you need very little at a time, just avoid using it alone for thick parts because the glue that comes out of epoxy with only silica tends to be kinda brittle when hardened, I've used for boats in conjunction with the wood flour and it makes an incredibly hard thixo putty 4- other inert stuff as filler: glass microspheres make for a light and sandable filler, polyester microspheres the same, chopped glass fiber will make anything rock hard and stiff, you choose what you prefer.
I would test a thin layer of epoxy with calcium carbonate for the detail layer, backed with epoxy with wood flour for a thicker shell, making it thixotropic with silica if the shape makes for a lot of wasted thickness so I can make a uniform shell. If the thing gets big I'd add the chopped strands for strength, and if there are extremely thick parts maybe having some glass microspheres would keep weight down significantly. I want it to be clear that this is an educated guess, since I haven't done this kind of mold with epoxy yet, but I've used it for many other applications, from casting to boat building.
Comments
The stuff you would need to formulate your own recipe is basically just this:
1- calcium carbonate (meudon white), inert fine powder, just a very fine filler, quite cheap, tends to thicken the resin
2- wood flour, extremely cheap, not fine enough for the detail layer, tends to thicken the resin, makes it extremely hard and reduces the tendency epoxy has to gum up sandpaper, it is used to make putty for modern wood boats for instance
3- amorphous colloidal silica (crystalline version is carcinogenic), this is the famous cab-o-sil Americans always refer to, it makes anything thixotropic, it's cheap and you need very little at a time, just avoid using it alone for thick parts because the glue that comes out of epoxy with only silica tends to be kinda brittle when hardened, I've used for boats in conjunction with the wood flour and it makes an incredibly hard thixo putty
4- other inert stuff as filler: glass microspheres make for a light and sandable filler, polyester microspheres the same, chopped glass fiber will make anything rock hard and stiff, you choose what you prefer.
I would test a thin layer of epoxy with calcium carbonate for the detail layer, backed with epoxy with wood flour for a thicker shell, making it thixotropic with silica if the shape makes for a lot of wasted thickness so I can make a uniform shell. If the thing gets big I'd add the chopped strands for strength, and if there are extremely thick parts maybe having some glass microspheres would keep weight down significantly.
I want it to be clear that this is an educated guess, since I haven't done this kind of mold with epoxy yet, but I've used it for many other applications, from casting to boat building.
Hope this was helpful!