Hi all,

We've been casting wax and resin in 18ct yellow and white gold now for 18+ months with no issues at all, but in the last month every cast we do is coming out with imperfections.

We thought we had a gas porosity issue initially, but I'm not so sure if that is the problem now so I'm desperately trying to trouble-shoot.

We always cast with either new metal, or a 50/50 mix of scrap and new. We've tried replacing our investment in the hope it may have been a simple contamination issue, but no joy.

We've tried lowering the temp of the melt (multiple times,) we've replaced the furnace (assumed our old one wasn't reporting correct temp,) we've tried delaying the quench, lowering flask temp ... I'm out of ideas.

Does anyone recognise this type of porosity (is it even porosity?) I've attached a picture which shows the type of imperfection we're seeing - they're large-ish, irregular shaped holes. There's no cracking, and no peppering of micro-grain holes.

Any help would be SO appreciated. My husband is the casting expert, but he's not too tech savvy, hence me posting with my poor terminology.

Thank you!

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