a wax model by Gustavo Aceves
One of the more frequently asked question for us is: which material i must use to make my model ? there is a short answer and a long answer. the short one is : every material hard enough to make a mould out of it. In any case if it is too soft there is a good chance that we can use some substance that will harden it so no problem anyway.
the long answer is the following. We can roughly divide models in two category : burnable and non burnable. from the burnable ones (soft wood, wax, some kind of paper , some kind of gum) we can obtain a direct casting , in other words we can attach some sprue on it, cover it by ceramic and proceed on the production like it is wax. Some customers prefer this because it is a little more money saving (you don’t have to do a mould and wax making), but the disadvantage is that you can only do a copy of your work and in any case can happen, not often but it can be, that the cast goes wrong, so you will loose model and sculpture in one time. another problem is that burnable material are often good only for little models.
Anyway even from the burnable materials you can obtain a mould and begin from that, thing that you have to do for sure with the non burnable materials. The non burnable materials have some advantage and some disadvantage, let’s see some:
plaster: it is the more classical material you can use; you can brake and repair it in case you have for doing the mould and you can work till you obtain a very fine surface, but is sensible to water so you have to imbue it with linen oil or some other substances that can preserve it if you want to preserve the model in the long therm
clay: also a very good and classic material to do mould out of it, but if you don’t cook it will crackle drying (an effect that some customers like)
plasticine: very good also, in the short time it will not harden so it will be sensible to physical touch , in the long therm it will crackle and often became musty, also, some rubber you can use for moulds don’t harden because of the content of sulfur in it, but you can fin it also without sulfur.
paper mache: very interesting material, but also very sensible to humidity, you will have for sure to protect it with some paint before to begin the moulding
wood, cooked clay, glass, plastic, ceramic, stone: all this material are eligible for doing moulds out of them but they all have the same problem: if you have to cut them to make the mould often the fixing is not invisible
fabric, gum, foam: they are good material but too soft, they need to be imbue or sprayed with some substances (generally wax or resin) that will harden it, but also will change forever the soft nature of the model….
a laquered plaster model by Theo Mackaay
Yes , it don’t exist a perfect material to make a model intended to be cast in metal, the only perfect one is the one that permit the sculptor to obtain the esthetic result he /she want. So in the end : the perfect material is YOUR perfect material , leave to us the rest of the problems.