Furnace cement.

This stuff went on nice, is rated for high temps, and sealed well. Now we will see how it stands up.

 

I thought you would be able to see it better than that.

Anywho, it is Rutland brand. What do you think. Can those guys up in Vermont know heating stuff?

 

Rutland makes some good stuff but bar none this is the best I have ever used.
https://www.lehmans.com/p-3143-hearthstone-stove-cement.aspx

 

Thanks Dex. Chimney section. I have a short section of black pipe from my ash cyclone on my Wood Gun boiler that then adapts to insulated stainless steel chimney. So there are two seems that need to be caulked. This stuff goes on nice with a small putty knife. Up until now I have been using tubes of high temp silicone. Decided to give this a try. So far, so good.

 

I tried it on my boilers flue pipe, got brittle and fell off after a while.

 

Try some of that stuff I linked Mike. That's what I always found with the Rutland....brittle.