I have a Nargesa H2 two burner gas forge and the compacted vermiculite insulation is crumbling apart. Not so bad on the sides exposed to heat but the backside and other non heat exposed pieces just keep shedding crumbs and disintegrating. I'm thinking humidity breaks this stuff down but the manufacturer of this forge says I'm the only one with this problem which I find hard to believe. https://photos.app.goo.gl/fjR6EwGEhNaoqi4X8