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Old 8th Jun 2010, 12:00 pm   #20
Aerodyne
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Join Date: Jun 2004
Location: Hampton Vale, Peterborough, UK.
Posts: 1,698
Default Re: Copying a control knob by moulding

Hi Billy

The reason I didn't specify a particular type of resin is because the best approach is to read the maker's literature via the web sites. There are many sources for casting resins and related materials.
However, I can tell you that I've used Isopon liquid resin (from car accessory shops on the high street) with success. It is best to use a very small amount of a filler material to modify the 'feel' and the opacity of this type of resin. Fillers can be talcum powder or even a little plaster of paris (or Polyfilla). Experimentation is essential before using a delicate mould.
As for colour, pigments are available from the sources mentioned and many others too. I have found that the best 'brown bakelite' effect comes from a mix of red, black and yellow colour. I've used ordinary paint - Humbrol, in fact - for this, but I have to warn that there is a definite limit to the amount as more than a few percent of paint to resin creates problems with setting and strength of final casting. Powdered pigment designed for the job is to be preferred.
Hope this helps a little.
-Tony
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