42" Pompeii in Kentucky

[ckdickerson]

Re: 42" Pompeii in Kentucky

Sorry I haven't posted in a while. I have fired my oven a couple of times and am dissapointed to say that I had some major craking of the dome. My first fire ws 100 degrees. Second 200, Third 300, Fourth 400. And then the fifth got away from me and exceeded 800. Thats when the cracking began some of them opened up nearly an eighth of an inch. I couldn't see fire throught the cracks but some smoke was making its way through. After the oven cooled the cracks decreased in size. Is this something to worry about? Is thereanything that I can do at this point? I haven't insulated or put the hardibacker aroung the outside yet so I still have easy access to the outside of the oven.

[Dolf]

Re: 42" Pompeii in Kentucky

I must start with the disclaimer that I am a mason by need and not by trade, but I have thrown a table slab which is supported on 2 sides (corner) only and which extends some 20" and includes a basin. It has been working fine for years now, so I am convinced that with some nice structure steel rod (rebar I see you call it) there is no reason why your overhang can not be the size you like. I boxed mine with wood. Drilled & inserted the rods 4" into the wall and cast it. Week later I took die box away and just touched the sides up with a grinder where my boxing left untidy marks and tiled it for finish. I know this is perhaps a long way from your original plan, but if you want the working space. (Perhaps I miss the whole plot :-))

[Eric Pfeifer]

Re: 42" Pompeii in Kentucky

Sorry I haven't posted in a while. I have fired my oven a couple of times and am dissapointed to say that I had some major craking of the dome. My first fire ws 100 degrees. Second 200, Third 300, Fourth 400. And then the fifth got away from me and exceeded 800. Thats when the cracking began some of them opened up nearly an eighth of an inch. I couldn't see fire throught the cracks but some smoke was making its way through. After the oven cooled the cracks decreased in size. Is this something to worry about? Is thereanything that I can do at this point? I haven't insulated or put the hardibacker aroung the outside yet so I still have easy access to the outside of the oven.

This is exactly what happened to me. One of the cracks was 1/8 inch thick and extended from the soldier brick row to the top of the dome, and was full thickness, and leaked smoke like crazy. After the oven cooled, I cut out the old mortar with an angle grinder and diamond wheel, and repointed the crack (both from inside, and outside--me crawling arms first through the arch with my fat gut) using this great buff-colored fireplace mortar in a caulk-gun tube, which you can get at home improvement stores. The stuff is easy to squeeze into the joints, and cures rock hard at 500 degrees. I have had two +700 heats since then, and no new cracks, and this original crack is sealed tight. I think these heavy brick ovens, especially if they laid upon an FB board (which are superb insulators, but do contract a little with the first heats) are under tremendous mechanical stress, and the heat is an invitation to relieve that stress via cracks. Once they settle in, and the few cracks repaired, I suspect they will be much more stable. Bottom line, the mortar in the tube is great for repairs.

[Dino_Pizza]

Re: 42" Pompeii in Kentucky

Oh, that's too bad CK. But don't worry. If you don't mind posting a pic of the crack it might help. But if its just credit card thick and smoke barley comes out, you could do what Eric just said quite successfully. You could also put additional mortar in it and a 1/4" thick patch on top from the outside. Yes, that area will crack again, BUT it will be just a hairline crack now and after you put on the ceramic blanket 2-3 layers thick and wire it down on the dome, no heat or smoke will escape and the oven will work exactly how it is suppose to.

Also, keep curing the oven to 700 or 800 deg a few days. I've experienced that the oven will form a few more hairline expansion cracks in other places, relieving the big crack and turning it into a common hairline. The weight of the dome and the mortared bricks will keep the structure sound, no worries there.

Is your oven a 42" dome? It does seem the bigger domes need a slower curing of the lower temps but IMHO the flames need to be spread out on the 42" floor and kept at temp for hours at a time otherwise on 4-6th firing (especially if it 'gets away from you') the dome gets a thermal shock it wasn't ready for b/c it's so big, it didn't really heat up properly on the 1st fires.

Your oven looks really good, you'll be in great shape and cooking in a few days!
-Dino