Well, it's been a few weeks since Bakeout #2, which resulted in a fine smattering of small bubbles in the furnace cement of the firebox and one big bubble in the base. Since then, I've done Bakeout #3, also "low and slow." This was followed by 6 cooks where I watched my temperatures and kept things under 500F.
All I can say is that I shouldn't have bothered mortaring the inside of the dome and the bottom.
To date, every time I've fired up Humpty, new air (steam) bubbles have appeared in the furnace cement. Currently, there are some the size of my palm inside the base near the firebox (haven't cracked them yet!). I'm sure our West Coast humidity is a big factor in the ongoing development of these new mortar bubbles.
The furnace cement did not bond very well to the claypot material. Upon curing, the mortar has shrunk and pulled away from the cooker walls. It's only a matter of time before the cement all delaminates and falls off.
So far, the mortar cracks are mostly in the base. More appear after every cook.
I thought the dome was immune, but the mortar has started bubbling there too. Note the sheen of condensation on the surface of the mortar.
A tiny gap can be seen between the mortar and the cooker wall where the mortar has cracked and flaked off. I expect the mortar to eventually all separate and fall off.
The furnace cement applied over Humpty's newly painted surface is also debonding and flaking off. More so with every cook as the heat weakens the paint-mortar bond. (The cement was used to repair the cracks that developed after the cooker had been painted.)
SIGHHH.... I'M THROWING IN THE TOWEL!!!
NO MORE REPAIRS!!!
I WILL COOK ON HUMPTY FOR AS LONG AS EVERYTHING HOLDS TOGETHER.
Project Humpty: SLIDESHOW
, PHOTO ALBUM