Green, Blue and white stuff - adventures in casting

I’ve been fascinated by casting ever since I was taught to pour plaster into animal tracks as a Cub Scout. In later years watching experiments in archaeometallurgy fired my imagination and is something I hope to experience first hand one day.

More recently I had an opportunity of a lifetime to be taught a little of the art of miniature casting by a friend in the business. In this case I was casting with  pewter using a centrifugal air pressure spin casting machine. 

Alas, metal casting at home is a bit beyond my capabilities at present so I have to be satisfied by simpler techniques. Enter stage left, Blue Stuff by Green Stuff World! This magnificent thermo plastic allows simple one- and two-piece moulds to be made just by heating the plastic in hot water. These moulds are often used with epoxy putty - such as Green Stuff or Milliput. 

When casting with Blue Stuff I favour having the mould supported with a small box to reduce warping during the casting process. It also allows for a nice flat finish to the back of the piece when using one-piece moulds.

The Blue Stuff mould was pressed into the supporting box made of coffee stirrers and MDF before the impression was made. While the master was in the Blue Stuff, I flattened the upper surface by inverting it and pressing it down onto baking parchment on a work surface. You have to have to experiment a bit to get the exact amount of Blue Stuff required but this really improves the end result. 

While I’m happy with the mould, I’ve had varied success with Green Stuff putty and Milliput in these moulds. The success of the final casting depends on carefully pressing the material into the mould to pick up all the surface detail. Incomplete edges and corners are common.

In a rare trip into the city today (over two years now happily working from home!) I stumbled across Green Stuff World Acrylic Resin (350g) in Mind Games’ CBD Melbourne store which claims to offer a non toxic ‘ceramic’ when mixed 3:1 resin powder and water. Setting in under an hour and mixing to a pourable consistency, I felt it presented a solution to the problems I was having with epoxy putty (and a significantly faster drying time).

Careful measuring always pays off. I will get small plastic ‘shot glasses’ for mixing in the future.

28mm windows poured with acrylic resin with Green Stuff and Milliput examples beside the mould

Green Stuff and Milliput bell tent castings showing loss of detail and incomplete casting. This Blue Stuff mould was also formed using tye surrounding box - it is just pictured here removed from it.

It’s early days but the first set of castings (windows for 28mm buildings and 6mm Bell Tents) suggest the acrylic resin to be a viable alternative. The edges of the window broke off in the mould possibly due to my handling and the need to allow further curing time. But the crisp detail is definitely encouraging. Is it too brittle for fine work? Time will tell!

Green Stuff Acrylic Resin castings demoulded after less than one hour!

I’ll keep experimenting and will certainly branch out into using proper silicone moulds and resin in the future, but Blue Stuff and acrylic resin are very useful tools to add to my modelling arsenal!