Wow, those are works of art! Omid, what kind of oven is that? I notice a lot of mortar on the top of the dome...ever get any on the floor?
Thank you! The oven is a Neapolitan oven (130 centimeters in internal floor diameter) constructed by Stefano Ferrara of Naples. There are many US pizzerias that use Ferrara ovens. The stuff visible on the internal surface of the dome are not mortar or grout. They are some kind of buildup or accretion that were not there initially. I do not know what they are, but they have been gradually accumulating over the past four years. I believe this is what eventually happens to any Neapolitan oven that is in used over a long period of time. Stefano has told us that they are nothing to worry about.
Last night, I gently scraped, with the aid of a turning peel, some of the accretion to expose the brick behind it. (See where the flash points to in the first picture below.) So far, I have not witnessed the accretions fall down on the floor. As long as they are not physically disturbed, they seem to stay where they are.
The last two picture, below, are close-ups of the accretion. When I press down on them with my fingertip, they turn into a fine white powder that is odorless and tasteless. Does anyone know what the accretions are made of? Good day!