Steam or smoke at thermal break

[TARibs]

So I've been curing the oven all week getting ready to cook this weekend. Fires have ramped up till todays was about 750. This morning I started to see either smoke or steam coming from the area where the flue gallery meets the Oven. I had put in a smaill thermal break (maybe 1/4 inch) here and filled it with Vermicrete. Up to this point I hadn't seen anything here. Feeling the thermal blanket it does feel damp so I'm guessing it got some water in it when we had our "Bomb Cyclone" two days ago. Tarp had stayed in place but the Canopy I had over it was blown off. I suspect the Lathe may have put some holes in the tarp and the blanket absorbed some water. Is this anything to be concerned about? Will definitely make sure the blanket is dry before the stucco goes on. Gotta love the fire though :-)

[david s]

It sounds to me like the vermicrete is still wet. A third of its volume is water so there’s lots there to eliminate. Generally if you see steam then you are going at it too hard. The vermicrete can swell and crack. Also it is better to do the drying fires with the oven insulated. An uninsulated oven is more prone to cracking when heat is applied.
Once you get the oven completely dry and all the black on the inside has cleared, if you plan on rendering the outer shell directly onto the blanket you will find that the springy surface difficult to work against. The usual procedure is to add a layer of vermicrete over the blanket first which provides a firm substrate to work over. It also allows you to restore a perfect dome form rather than the lumpy blanket form.

[TARibs]

Thanks David, yes the vermicrete has cracked ( I can see it on the inside), so I'm going to have to dig some of it out and remove it to seal it up again, (I don't like the idea of the vermicrete really it doesn't seem particularly resilient) which will mean removing part of the blanket, (the pictures are from a time before the insulation was placed) The oven has 3 inches over most of it and 1 on the flue gallery (you may be able to see in the last picture). I don't have room for the vermicrete layers as I'm at the edge of the table. I've been very careful putting the lathe on and I still have a very nice shape at this point (still a bit more to do) . Not too worried right now about losing the nice shape, the way things are going it should be fine shape wise. I don't think it was wet prior to the storm I think it absorbed water then. I had fired it for 5 days previously without any steam or moisture being present. Bit of a bummer but don't have much choice it looks like.

Tom

[TARibs]

So the issue is the vemicrete just doesn't adhere to the Cast flue and I'm not sure how that is fixed. Two different materials with the cast piece dry I don't see it happening. I have two possible Ideas. One try to seal it with the same stuff I used to hold the Chimney mount in place (Permatex Ultra Copper Adhesive) or cut a small horizontal groove in the cast piece so, almost make a key for the Vermicrete to go into. I'm surprised more people don't have this issue. The Vermicrete seems completely dry.