Casting in resin

Tim Brien

Registered
My son is building an "RNLI" lifeboat and needed to build an interior to super detail the boat. It is in 1/25 scale with twin jet boat drive. Apart from interior consoles the seats look to be time consuming to make multiples, so he made a buck to use for moulding.

A look on You-Tube revealed an inexpensive method to make a mould using common silicone sealant available in hardware stores and supermarkets. The secret is to squirt the sealant into a tub of warm soapy water. The sealant is then massaged into a ball for several minutes making it very pliable. The sealant is then pressed into the box containing the buck to be cast. The box can be a very simple affair, however a mould release like cooking oil or Vaseline/petroleum jelly should be applied to both the box internal surfaces and the buck..

After 24 - 36 hours the now cured sealant is removed from the box and the buck removed. One can then flip over the mould and reinsert into the box thus allowing the box to support the mould to minimise distortion when casting.

After casting (my son used polyester body filler used for car repairs) the cast item is removed and then cleaned up and removed of any mould release. This method may not be suitable for casting fine detail, however, in my son's case, it proved to be a low cost alternative plus saved time actually constructing the number of seats required from scratch.


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That has a lot of possibilities Tim, any old silicone sealant will do I take it?

For the box I know a person who uses the big Lego type bricks to make boxes, they can be made to order size wise and can be dismantled to slide the mold out.
 
Yes, I assume either normal sealant or the neutral cure used for guttering. Personally I would go with the neutral cure as the normal sealant will destroy plastic. I know from bitter experience that the sealant will dissolve plastic. Some years ago I built a massive narrow-gauge 4-6-6-0 Mother Hubbard locomotive. It was longer than an LGB Sumpter Valley and ran as smooth as silk but alas, a minimum 12 ft diameter curve was needed (the rear drive was fixed in the body). Two weeks after sealing two cast weights in the firebox over the rear drive all that was left was the skin of the paint. The sealant had dissolved the plastic totally where it contacted it.
 
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