by Mike - Alumilite » Wed Dec 14, 2011 5:53 am
A few ways you can do it ... first simply paint on a thin layer of Flex 30 or 40 after demolding the hard casting you want to overmold.
If you need detail in the outer layer or film, you'll need to make two molds ... one of the hard plastic inner piece and secondly one of the outside shape of your finished piece. Then use the inner casting as an insert into the second mold and pour around it. If the soft plastic surface coat is really thin, this option will be extremely tough and you'd be better to simply demold the inner piece, and paint on a Flex coat afterwards.
If you have natural mechanical locks on the inner piece you could also try dipping it in a clear coat of Alumisol. This will give you the softest surface coat but will not chemically bond to the hard resin core. It will hold but not chemically bond and therefore would need some good flow through or locking features in the design.
Mike
Alumilite
800 447-9344