Casa2g90 Install in Portland, Oregon

[ASPLM]

Thank you. I am trying to play it cool about the cracks. Not truly in my nature. I’ll do the Visqueen trick tomorrow on one more scary fire and probably stucco later this week.

[SableSprings]

If it helps, years ago (before IR guns ), bakers often used either the "tossed flour test" (which really only gives you approximate cooking surface temps) or the size/appearance of key oven cracks to help them decide when the oven was ready for the loaves to be loaded. As the oven mass heated up, the cracks would get larger as a direct relationship with the oven mass temperature...and as the oven cooled down, the cracks would get smaller. A much better way to gauge the heat loading of the mass. So if you think about it that way, as we said in computer programming, it's not a bug...it's a feature

Structurally with the dome design, cracks don't weaken the oven. In fact, since the entire oven actually expands and contracts with the firing cycles, you WANT some cracks that act as consistent expansion "joints"...and they are pretty inevitable because of thermodynamics not the builder ().

Years ago there was a post noting that firing one of these ovens for pizza was basically done by having "a fire from hell". I always loved that thought for some reason.

[ASPLM]

Thank you. That does reassure. Is the dome reinforced with steel?

[UtahBeehiver]

I do not believe FB uses SS needles in their casts but I think they use Poly Pro fibers. You will have to ask them.

[ASPLM]

The cracks are invisible when the oven is cool. The entire dome cleared after I closed the door., Here goes the stucco!

[ASPLM]

Any thoughts on timing between stucco coats? Is it OK if I apply one coat tonight (Tuesday), and then maybe can't get to the next coat until Sunday?

[SableSprings]

Make sure you rough up the surface of the first coat (scratch coat ) before it hardens. We simply drove a row of nails through a long, thin piece of wood (like a paint stir stick) and then went over the first coat to create the "scratches" all over the surface. As long as you've got something for the second coat to grab on to, the timing of that application shouldn't be a problem. I'd dampen the first coat lightly just before you apply the second to give it a little bit better bond between the layers. You'll find that the thin stucco coat can dry/harden fairly quickly depending on the weather, so make sure you've got everything ready to go before you start mixing up the stucco.

[ASPLM]

Thanks. I used my hand saw to thoroughly scratch the coat after floating it. Should give a good bite.

I started application in the evening and it’s been really humid so it was still pretty uncured this morning. I need to fix some shaping issues, so I’m going to add a second base coat tonight. Since I’m putting a mosaic over the whole shebang, I’m just going to Redgard over that after it cures. Redgard says 28 days before applying to concrete substrate, but I’m guessing a week or so should be ok for a thin coat like stucco. I’ll probably wait until I’m doing the mosaic to put the Redgard on, and it’s under a canopy so only moisture exposure is dew until then.

I asked Redgard if there was a limitation on surface temp for substrates after the Redgard cures. They said 170F but couldn’t provide documentation so it has a decidedly PFMA feel to it. Still, better a number out of their butt than mine. We’ll be going to 900F on Sunday for our first official pizza and I’ll monitor the outside temp then to see where it gets. It’s been barely warm on previous firings, so I’d be surprised if it’s anywhere near 170F, but I’m always surprised at my inability to guage temperature.

[SableSprings]

Yes, I think most builders have used more stucco to simply improve the shape than to just provide an outer cover. It's really hard to see all those bumps and low spots until you get that first stucco layer on...and then you realize that the second (or third ) coat is going to involve some serious adjustments to the outer curves. (p.s. This is a great time to get your significant other to be involved in "spotting" places where the dome is "out of shape"...similar to setting up the Christmas tree, if it appeared straight in the stand to you--it's a pretty good bet you're wrong ).

I rebuilt our bathroom several years ago and made the base concrete shower pan. My understanding from Redgard at the time, was that the 28-30 days before applying it to fresh concrete was to make sure that the concrete had properly cured and excess internal water had evaporated/escaped. They also told me that by waiting for the month, you were pretty sure that any cracks in the concrete would be "set" so you could either repair them or make sure the application of Redgard created a completely sealed layer over any problem areas. I think you're good by waiting a week for the stucco to cure/dry before painting on the membrane. The other nice thing about the Redgard is that you can apply it shortly before your tile. As soon as it changes from pink to red, usually overnight, thinset (for setting the tiles) will adhere to it without any further surface prep.

With the covering of the insulation batting, the temperature will be slightly higher on the outside than uncovered. Even though it may get a little warmer on an extended firing, I'd be really surprised if you got anywhere close to 170F in the Redgard layer.

Looking forward to hearing about your first official pizza party...remember that 1) Make sure the prepared pizza slides around on the peel as you move towards the oven--I use a little rice flour on the peel to provide slippage, 2) Expect to sacrifice at least one pizza to the Pizza Gods, 3) Thicker tomato or cream based pizza sauce won't make the pizza skin soggy as quickly, 4) Make sure you or your guests don't pile on the toppings--you will have much better results, and 5) try to limit the number of toppings available...having a bunch of little containers of leftovers isn't very fun when they reappear in the back of the fridge next month .

[ASPLM]

I've been liking the model of having things to put on the pizza after cooking. So you make a basic cheese pizza, then throw dressed arugula and soft cheeses on top after cooking. Also, we were at a bar the other night where they had a meat plate with warm flatbread. I started fantasizing about doing that, and pulling perfect fresh flatbread out of the oven to accompany. READY TO STOP BUILDING AND START EATING, but so much more work to be done.

[ASPLM]

Ok! Second layer went on and it has the shape I want. I finished it at 9pm, misted it the next morning before I went to work, then I wrapped it in burlap when I got home at 5 and gave it a decent hose down. Now I’m worried I just overwatered.

I was planning on going right back up to 900F on Sunday, but I’m concerned the stucco base coat of about 1/2 “ is permeable enough that the big water load I put on it will soak through and wet the insulation.

Did I screw up?

[UtahBeehiver]

You have to be really careful with firing right now. If the insulation is wet at all from the stucco installation, when the water converts to steam the volume increases a 1000 times plus and without any way to relieve the volume/pressure the stucco has a high probability to crack. This is the point of construction where we see builders get a little too excited and impatient and move too quick and fast and damage their work.

[ASPLM]

So are you suggesting another cure cycle? How should I approach this?

[SableSprings]

Since the insulation batting may have gotten a "little damp", it may be a good idea to do a medium fire Friday or Saturday before firing it up to pizza temps on Sunday. The stucco layer is a bit fragile at this stage, so letting a lower fire dry out any remaining (or new) moisture/dampness now seems like a worthwhile investment . This is a situation that a vent (breather cap) built into the insulation/stucco interface really helps reduce/eliminate cracking from steam expansion.

Realistically, I'd be surprised if you got much moisture transfer through the stucco to the insulation...just think of a pre-fire a day or two ahead as pre-heat for the pizza party

[UtahBeehiver]

Plus 2 on Mike's comments. As noted in your previous post, you said you wanted to right back to 900 F. If there is any moisture in the insulation, the thermal transfer of heat is high due to conductivity of the moisture, this means that if the outside temp of the brick in the dome under the insulation exceeds 212 F the water will flash to steam and build up volume and pressure and crack you stucco. You are the tortoise in this race not the hare.