Refractory caulk advice

[dmun]

Those who have followed my geodesic oven progress know that I've had lots of cracking. The first significant crack was over the oven entry, and now one of the bricks that form the top of the archway has cracked loose, and fallen.

Does anyone have any experience with the refractory mortars that come in a tube, like this:

Refractory Brick Mortar, 3200 degree 11 oz. tube - eBay (item 130429936797 end time Sep-16-10 06:31:00 PDT)

Would this be any better than mixing up some heat-stop and re-mortaring it in?

Any other suggestions?

Thanks

[Tscarborough]

As a rule, while those caulks work well to make chink repairs, they do not have much or any adhesive properties. I would use refractory cement of some type. If you can't find a small amount locally, PM me and I will send you a little bit of a product called Insulstick, which is made for this type of repair and is nice and, well, sticky.

[RTflorida]

I used that same product (from the same ebay vendor) about a year and a half ago. I was attempting to seal a reoccuring arch crack that went up to and around my Duravent pipe. Since this product is not rated for exposure to the elements I top coated with mortar. Keep in mind, this was on the exterior of my igloo, the crack forming along mortar lines. Didn't work, the crack came back worse than before.
Long story short, I found a better solution. I know my problem was entirely different, but I would try something else before buying this sealant again for any purpose.
In reading about the Insulstick, I would certainly give it a go.....seems perfect for your application. Says it is extremely sticky and will adhere to virtually any surface.

RT