by johncast » Mon Apr 14, 2014 9:22 pm
Interesting post here, so I thought I add a bit to this interesting area of mould making.
Forming up the items for the first part of a 2 part mould , I find myself doing this 95% of the time to make resin and wax injection moulds. To get the results I want.
I guess I have been lucky but the average and cheap modelling clay I bought in the local newsagency works great. No mention of sulphur in the material but having used this for 80 or more moulds I don't have problems only that it takes a bit of work to remove once the first half is set. If the temperature is cooler the clay comes away a bit easier from the rubber.
Be advised that this could be a very different story with other rubber materials besides the rubbers I am using, which are the Barn's 4601 pink for resin moulds and for the wax moulds I use Slastic J 4130. from Era polymers and barns 4670 white..
The brand is Belgrave modelling clay and is a good pale grey. Item 1313 the label says
Quill stationary Park Road Regents park NSW 2143 Australia.
Made in Mexico
The biggest problem I have had is not washing the patterns before moulding, ESPECIALY RAPIDPROTOTYPE computer patterns. Gently with fine soft brush in warm water and dish wash liquid always ,,always wash the parts..before moulding. Hope this helps
Johncast