I use silicones for mould-making and these can react with sulphur in modelling materials. Does Newplast contain sulphur?
Newplast does not contain sulphur and is perfectly suitable for use with silicones in mould-making.
I have quite an old bar of Newplast and it has dried out and hardened. Is there anything I can do to soften it?
Newplast does not contain water and therefore it is non-drying and non-setting. It should remain pliable and workable for several years. However, nothing lasts forever and Newplast might become a little harder and more brittle with age, particularly if it has been exposed to cold conditions during storage. It can often be re-softened with gentle heat, e.g. with the fingers or in a container in warm water. We have heard that five seconds in a microwave can work, though we have not tried this ourselves and you do so at your own risk. Working a little linseed oil or petroleum jelly into the Newplast can also be effective. If these measures fail, the Newplast is past salvage and should be replaced by purchasing fresh material from your favourite stockist.
Can Newplast be hardened and/or made to set?
No, this is not possible with Newplast. Our other products Newclay (an air-drying modelling clay) or Uro (a heat-curing polymer clay) are recommended as alternatives to Newplast in applications where a permanent finish is required.