I just tried making a silicone mould from a master which all seemed OK but after I got the first piece out of teh mould there were a lot of dust marks on the  piece. I presume the dust had been attracted to the mould surface. Am I doing anything wrong?

FBS

Only suggestion is work in a cleaner environment. Perhaps clean the mould to ensure no dust has settled on it prior to use.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Silicone molds have a lot of friction. Meaning hard to wipe clean. So dust just hanges on.

You might try wiping the surface clean with petroleum jelly. (note:i havent tried this so test first)

Fred 

The working are was not that dusty, and there was not a lot of time between making the mould and using it. Could it be static attracting dust?

Or, should I try another type of mould material. The silicone rubber is very soft and that makes cleaning difficult?

It could be static in the environment you are in. 

Try washing the mould out properly and let it dry before using again.

It's very unusual for people to have problems with silicone base moulds as they are so simple.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

you know i was like mad when first putted carbon then resin , next brushed dry 120 then 180 and once again and started to leave tiny holes filed white so i started to use this method not clean surface before laying Nefrase but i cleaned by - Acetone and they done all bad things i suggest. and what i recently found i always had problems with bubles tiny that leaving after i laying with brush resin - problem was cheap simple brush so use hardly flexible brush as with soft brush you gonna kill yourselve with playing with bubles. i hope my exprience helped.