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Mysterious "wet" spots inside the oven

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  • Mysterious "wet" spots inside the oven

    I am assembling a Premio 2G. After dome was assembled and mortared, I waited two days before starting curing. I am curing the oven before putting on any insulation so its important to note that nothing has touched these oven walls except the FB mortar that was put on 4 days ago. I have an enclosed tent around the oven so no rain water has come near the oven either.

    After reading a gazzilion curing thread, I am going slow and steady with the curing process. For the first two full day, I used a continuously running space heater to work my way up from ~80F to ~150 F (as measured at top of dome and the floor). The outside walls of the dome peaked at high 90s. There was no resting period during these two days (i.e. space heater ran non-stop). After about two days, I noticed a few "wet" spots appear inside the oven. The marks appear oily but are not oily to touch. If it is water, I am not sure where it is coming from. Two of the spots are near a joint but the one by the oven entrance are no where near any joint. These spots do not appear on the outside of the oven.

    Has anyone seen this with either the FB modular kits or their own builds? Any suggestions on what to do?

  • #2
    There will be some moisture left in the casting. That is what the "curing" (a better term is "drying") cycle is for. However, what you are seeing may be the residual mold release agent from the casting. I'm not sure if Forno Bravo's formula is proprietary, but it is going to be a vegetable oil based. Moisture will be driven out in the "drying" cycle. Any release agent left on the casting will go away when the dome first reaches dome clearing temps.
    Joe Watson " A year from now, you will wish that you had started today" My Build Album / My Build


    • #3
      Thanks. I will get a confirmation from FB and continue firing. Appreciate the quick answer.


      • #4
        Hello Kababia,
        What you are seeing is completely normal , you will most likely experience moisture baking off from the inside of the dome the first few days of firing. You may also notice dark spots from the releasing agent that we use on our steel oven molds (doughnut grease) . Keep up the good work and continue to cure your oven at low temps.