Mix ratio’s

If you are using GP resin (a Polyester) for your casting, you must understand the principles of altering the catalyst ratio to suit your work. You must be aware of the relationship between volume and surface area before you begin casting. If you do not, you may be endangering yourself and other workshop users’ health.

(See Polyesters- GP resin).

If you are using Polyurethane’s ensure you know the correct mix ratio because there are so many types of Polyurethane resin, some may be a simple 50:50 mix, others may vary. (see Polyurethane’s- Resins and Rubbers) 

Choosing your casting materials

What you choose as a casting material is not limited to resin, rubber, foam, wax or plaster; any substance that can change its physical form may be used. For example, liquid water can turn to solid ice and molten chocolate can re-solidify when cooled.

Think of other materials you could use for casting like jelly, sugar, gelatin, lard, butter or toffee.

If you can make a liquid turn solid, it can be used for casting.

Your imagination is your only limit!

There are 4 main classes of resin used for casting:

Polyesters- Cheap, readily available and

                   versatile but volatile

Polyurethanes- Expensive but good

                 mechanical properties highly  

               versatile, but very harmful volatile

Epoxies- Expensive and volatile,

Eco-resins- Expensive and can be difficult

                   to obtain, but user and very

                   environment friendly

Other materials for casting include:

Silicone- Largely user friendly, more 

              readily available than equivalents

Wax- Cheap, readily available, versatile, 

          an inert material

Plaster- Cheap, readily available, versatile

              and user friendly

There are many materials available for casting.

The type you choose is dictated by the type of object being cast and the users needs.


Various ‘Layering’ techniques



Marbling effects using GP resin

GP resin Layering effect


Brass and GP resin taken

from a Split mould


Clear resin and Acrylic encapsulation


Polyurethane rubber Layering effect