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don_jarr · 10-09-2007

Hi m8

I have and do sometimes use hot melt rubber, but due to using polyurethane resins mainly which generate heat while curing, it tends to sticks to the hot melt rubber.

You should have a look at this web site, www.tiranti.co.uk as they sell all moulding stuff. If you only do smallish things, it might be worth buying some proper addition cure silicon, and 5 minute polyurethane resin, and do them that way. Poly resin is much better for small amounts as most are 1:1 which means you can buy those children’s medicine syringes and mix that way. I do a lot of small stuff that way. I bought some 100ml plastic bottles which I put resin and hardener into and the syringe bottle neck bits fits in the top perfectly, that way I can fill the syringe accurately to half a millilitre of each.

I also find on smaller things, to make the mould in two halves, but fit a fill tube into the mould when casting, so the resin is injected in via syringe from the bottom of the item being cast, not the top. You can fill it slowly so the air is pushed out the top as the resin goes in the bottom.

All said and done, however the best way to do smaller intricate things is to pressure cast, but this is a whole new ball game requiring far more equipment. The plus side is very detailed wafer thin castings perfect every time, air bubble free.

If you have any pictures of bits, it would be good to see what you are doing.

Don

10-09-2007	#10 (permalink)
don_jarr Scale Model Member Join Date: Aug 2007 Location: Essex My Models: I never throw anything away. Visit don_jarr's Gallery Posts: 66 Images: 9	Hi m8 I have and do sometimes use hot melt rubber, but due to using polyurethane resins mainly which generate heat while curing, it tends to sticks to the hot melt rubber. You should have a look at this web site, www.tiranti.co.uk as they sell all moulding stuff. If you only do smallish things, it might be worth buying some proper addition cure silicon, and 5 minute polyurethane resin, and do them that way. Poly resin is much better for small amounts as most are 1:1 which means you can buy those children’s medicine syringes and mix that way. I do a lot of small stuff that way. I bought some 100ml plastic bottles which I put resin and hardener into and the syringe bottle neck bits fits in the top perfectly, that way I can fill the syringe accurately to half a millilitre of each. I also find on smaller things, to make the mould in two halves, but fit a fill tube into the mould when casting, so the resin is injected in via syringe from the bottom of the item being cast, not the top. You can fill it slowly so the air is pushed out the top as the resin goes in the bottom. All said and done, however the best way to do smaller intricate things is to pressure cast, but this is a whole new ball game requiring far more equipment. The plus side is very detailed wafer thin castings perfect every time, air bubble free. If you have any pictures of bits, it would be good to see what you are doing. Don