I discovered Blue Stuff when I saw my son casting shields for a troop of Roman soldiers. Blue Stuff is supplied as a thermoplastic strip which softens when heated and takes impressions remarkably well. Once cooled, it forms a little mould from which repeated copies can be cast in the same maker’s Green Stuff, which is a two-part epoxy putty. Once used, Blue Stuff can be heated and reused for a different mould. I used both materials to cast the cosmetic front springs for the 2-4-0. Blue Stuff can be used to make some quite sophisticated moulds and may just help us to create essential cosmetic parts, where 3D printing may still be beyond the reach of some of us, and where required quantities are small. Just bear in mind that copying and casting the odd part – as I did with this whitemetal spring – for your own use is fine. Doing the same and selling it for commercial gain is piracy – and illegal. Web: www.greenstuffworld.com
7 Next day I extracted the spring unit and was pleased to find a close match to my original. A quick clean-up followed before painting and installation. The more copies you need to produce, the more useful Blue Stuff will be.
1 Blue Stuff on the left and the two-part Green Stuff on the right. I made a pattern for the front spring using two thicknesses of 40thou styrene sheet and various pieces of styrene strip glued together and allowed to harden before shaping.
4 Having left the Blue Stuff for several hours to cool and harden, I removed the master carefully with the point of a craft knife. I then cut off equal parts of the blue and yellow strips of Green Stuff and began mixing it.
2 I cut off a small piece of Blue Stuff using a craft knife and immersed it in a mug of water. This was heated in the microwave for three minutes. Take care – the mug and water will be hot! Fish the Blue Stuff out with a teaspoon.
3 Blue Stuff will stay warm and workable for a few minutes. I pressed my spring ‘master’ face-down into the material using a flat steel rule until the back of the master was flush with the surface of the Blue Stuff.
6 I used a steel spatula to press the Green Stuff into the mould. I could see through the mould from the back, so I could check when the Green Stuff was fully packed in. I then smoothed the top surface and left it to cure overnight.
5 The blue and yellow, two-part Green Stuff is mixed between the fingers until fully blended – and green. It is then ready for use.