Spent a bit of today reading up on investment casting, to cast various hardware for banjos.
They'd have to be made out of brass, since that's what's expected. And being very hot brass, i'd prefer to do it with a partner (I learned my lesson when I tried juggling the entire operation with aluminium). If it was just myself i'd consider holding my breath and standing up wind of the crucible, but with somebody else involved i'd have to go all out on safety.
I've been googling about trying to see if I could find anything on respiratory protection for zinc fumes, but didn't find much. I should've wore respiratory protection when I blew the layer of dust off my Cromwell tools catalogue, but all it said for the filters in there was protection from 'fumes'. That might include zinc but I'd prefer something more concrete.
What kind of filter rating would be required for protection against zinc fumes?
Also, while i'm at it, where's a good place in the UK to buy silicon rubber for mould making?