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adhesive for insboard?

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I am trying to glue up some pieces of Insboard equivalent to make a firebox (which will then be lined with hard refractory) using high temp furnace cement. That stuff is quite sticky, but it doesn't adhere well to the slightly dusty surface of the board. I tried brushing the dust off the surface, but it seems to just make more dust. Does anyone have any tips? 


I considered using hot glue to hold the pieces temporarily. (The glue would burn off when the forge is fired, but that's OK. By then it shouldn't matter. I hope.) But I suspect I'd have the same problem with hot glue. Nothing sticks well to dusty surfaces.

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Any of these boards tend to warp under repeated heating (not to mention releasing glass fibers after firing), so you are being prudent to use a hard refractory lining.  I would recommend Kastolite 30, as it also has some insulating value as well as reasonable flux resistance. 


I have always used mechanical pinning systems to keep my board in place.  Nichrome wire or manufactured stainless lagging pins work quite well.  If you cover it with a 1/2" -3/4" layer of Kastolite the wires will hold up fine.  If you must use a high temperature furnace cement I would try to "butter" the board surface you are going to glue to before use (and be absolutely sure the cement will not melt at the temperatures it will be exposed to during firing).  You can butter the surfaces to be bonded by spraying with water till it is slightly damp, then use your high temperature mortar.  Note that these cements and mortars are designed primarily to seal cracks, not create structural assemblages.


Good luck.

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Thanks. Yes, the plan is to line the firebox with around 1/2" of Kastoline 30LI. Once it is in place in the forge, the Kastolite will provide the interior structure and compressive strength, and compression from the surrounding ceramic blanket should hold the other bits in place against the liner--I hope. All I really need for now is for everything to hold together and not leak while I cast the hard refractory liner and emplace the box in the forge. Sealing the joints is the single most important function of the furnace cement. (It would not have been essential to use ceramic board for this project, but I had extra left over from another project and it seemed well-suited for this.)


I do have some Kanthal A1 wire from a long-ago project that I could use for mechanical fastening. I'll think about using some of that to reinforce key junctures. Thanks for the tips.

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