Jesmonite & Aqua Resin
This page is about Jesmonite & Aqua Resin, check out the main project index for the rest.
Jesmonite and Aqua Resin are both Acrylic-reinforced gypsum products, which means they are similar to plaster with their own liquid that acts as a binder. This article shows example projects and also some strength testing.
As I mentioned in the Polyester and Polyurethane resin articles, both are considered toxic in liquid form. Jesmonite is however based on Gypsum and an acrylic binder liquid, both of which are non-toxic. This means that you can safely use Jesmonite in doors without a respirator, although it’s still worth checking the manufacturers website for product data sheets. Jesmonite is a UK product, for a similar product in the US, look for Aqua Resin.
Pictured above are Jesmonite liquid and powder, which are mixed at a ration of 1 part liquid to 2.5 parts powder, and some Jesmonite thixotrope. The thixotrope product makes the mixed resin thicker so that you can brush initial coats into a mould/onto an object before backing it up with fiberlgass mat. As with Polyester resin, Jesmonite is brittle in thin sections without reinforcement, so a specific Jesmonite quadaxial glass fibre mat is also available. This mat has a very open weave to allow wetting through, although I’ve personally used standard chopped stranded mat as well as surface tissue with no issues.
My original attempt at an Iron Man suit was cast in Jesmonite, although it was very heavy due to the Gypsum content:
I pretty much always use Jesmonite for rigid mother moulds however, like the ones you can see in my most recent Iron Man suit moulding and casting pages. Some of these mother moulds are reinforced with Jute Scrim, which is made from Hessian, and some of them appear yellow in colour because I used Jesmonite liquid with ‘any old plaster’ powder – it was actually some Yellow Dental Stone powder I had lying around, which works just as well if you’re not too bothered about the resulting weight:
You can also obtain specific Jesmonite stone and metal filler powders for mixing into the resin to various cast effects. These products are specific to Jesmonite resins due their grain size. You will then need to polish back the cast item to get a nice stone or metal effect surface finish.
Due to the fact that Jesmonite is not solvent based, you can use it to directly coat Polystyrene and other foams without it melting. This is quite useful for large scale prop pieces for theatrical use.