Cold Casting to produce a metallic effect from a plastic is becoming very popular. Even a babies hand can be replicated and turned into a keyring with imagination and commitment, and of course a budget!
There are many methods by which this can be achieved. At the bottom we have a You-Tube Video on this subject. The video shows a back filled method to cheapen the process and also covers some patina finishing with coloured waxes!
First you need a RTV Silicone Mould. Once made the fun can begin. You will need Fast Cast Polyurethane Resin and a metal powder, the choice is yours as to which effect you are trying to achieve. We stock Bronze, Brass, Copper, Aluminium and Nickel.
Make sure your mould is clean and free of contaminants. Measure out a small batch of Fast Cast into two pots. Add Metal Powder at a ratio of 1:1 to the total weight of both parts. eg 500g A and 500g B, add 1kg of Metal Powder to the Part A and disperse. Allow to stand for a few minutes to allow air to escape, the powder will sink to the bottom, this is normal!.
Now add the Part B and mix well. Here is where differences in technique will start to appear.
In the movie, a brush on coat is employed to :
a: Prevent drop out and have some areas without powder
b: To make the cast more economic
If the piece is very small, I usually use just the resin and powder with some pigment (black works very well) to bring out the additional shine. However if a much larger surface area is present, the brush on method works brilliantly. If you are unable to brush on, then agitate or swill the mould and coat the surface repeatedly until the material begins to gel. THEN LEAVE IT BE TO SET!
Now measure out your backfill mix. Under measure rather than over measure. I tend to pigment this black, but you could match the metal colour with use of our PU Pigments. Add marble sugar to this to rapidly build weight and simulate metal better!
Pour this onto the back and allow to set. In the case of a swilled coating, with a narrow opening, pour thru that opening. Again allow to set.
After an hour our fast cast is more than ready to demould. Remove your cast from the mould. It will NOT look metallic at all as the metal particulate is encapsulated fully by resin. So to expose this bound powder, rub the surface with super fine 00 gauge wire wool. It must be fine or you will erode the plastic too much! The more you rub, the more powder gets exposed, but do not go to far with this! Do not forget to clean off the wire wool debris!
You can then add patinas, waxes and other effects to improve the look, but thats the basics of Cold Casting. Sit back and watch the video, its very worthwhile!
This particular process is a little complicated but gets the result required. This particular video shows the manufacture of a shield, with a back fill of padded cheaper back fill resin. The Patina effects are mainly achieved with waxes.