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Dark stains developing on outside stucco

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  • Dark stains developing on outside stucco


    I recently purchased a Casa 80 kit and finished building it a few weeks ago. I used four layers of insulation, one layer of lath, one layer of insulating cement (portland + vermiculite), one scratch layer for stucco, and the final stucco layer.

    Here is the curing schedule I ended up doing:

    - Oct/18: last layer of stucco
    - Oct/25: small fire (mostly paper and a few small wood chuncks)
    - Nov/3: small fire (two larger pieces of wood)
    - Nov/4: three pieces of wood
    - Nov/5: 4 pieces of wood (temp reached 500F)
    - Nov/6: 6 pieces of wood (temp reach 800F at top of dome)

    After the last fire on Nov/6, the soot on the top of the dome cleaned out and I saw that some cracks had developed (see picture). I did the paper clip test suggested by Anthony Rodriguez (Forno Bravo Tech Support) on this forum and confirmed that they are hairline cracks. no worries there.

    I am writing because dark stains are developing on the outside of the oven (see picture). I wanted to ask you if you have seen this before, what may be causing them, and whether or not I should be worried.

    Additionally, I may have been too aggressive on my curing schedule, what do you recommend I do now. A few more small fires (500F) or is the oven ready for bigger fires?

    thank you for your help

    Click image for larger version

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    Click image for larger version

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  • #2
    Are the referred temperatures of the air within the dome or are they of the actual dome's bricks temperature?