Not sure about chalk. May work. I’ve only used spray moly and spray graphite. Both last for several casting sessions. No adverse affects to moulds.
Once made a run of 5,000 356402s using two DC moulds. One treatment lasted the whole 2-3 day session. For a friends Swedish K. The treatment applied to a warm mould lasts pretty good./beagle
Once made a run of 5,000 356402s using two DC moulds. One treatment lasted the whole 2-3 day session. For a friends Swedish K. The treatment applied to a warm mould lasts pretty good./beagle