Curing methods?

[MK1]

Re: Curing methods?

Rodney,
I think I would cure before final render, unless you have some kind of venting for your insulation cavity. This thing will still throw some moisture and you don't want it trapped in your insulation.
This is where the gabled house design has an advantage.
If you can buy or borrow a banjo burner, you can rig the steel pipe for less than $10.

Mark

[Rodneyf]

Re: Curing methods?

Mark, I was toying with the idea of curing after the insulation but before the render and I think you are right so I will go with a fire next week. I think my dad has a ring from an old BBQ that I might be able to borrow and rig as a burner.

[MK1]

Re: Curing methods?

Rodney, I think that's exactly right (cure after insulate, before render) according to your furnace guys. With the propane you will save on alot of beads.
Good luck,
Mark

[Gromit]

Re: Curing methods?

Driving out the moisture at the 200c stage took a full 24 hours. I have 1.5" of refractory mortar on the outside of my bricks and I believe that was the never ending source.

Mark,

I think the bigger issue may have been the stainless vapor barrier between the oven and the insulation. (If I understand your build correctly.)

I followed this curing technique on Friday/Saturday and the dome only steamed for 3 to 4 hours (no extra layer of mortar on mine). It started raining during the curing, so I covered it with a tarp. When I pulled back the tarp I noticed the steam for the first time--and noticed that the top of my insulation was quite wet.

I think that your steam may have been condensing against the stainless, dripping back on the dome, and re-vaporizing over and over for 24 hours until it all finally escaped.

[MK1]

Re: Curing methods?

David,
I think you're right, my inner stainless dome did prolong the dry-out. Also I think my added layer of mortar was the main source of water. Today I might have to start on an ark. It's rained 3" in the last 6 hours.
I'm glad to hear about another instance of this curing technique. I haven't checked your build thread yet. Any cracking?

Mark

[david s]

Re: Curing methods?

I did the the same thing. I put a layer of alfoil outside my insulation. I poked some holes in the alfoil in a few places to allow moisture to escape. The oven took ages to cure and was always hot where the holes were. My idea was that the alfoil would prevent moisture from being sucked away from the outside render. That worked ok but it also traps moisture under the alfoil layer. For many firings after the outside shell was finished the oven was still hot ion the outside where the holes in the alfoil had been made. I wouldn't do it again.

[Gromit]

Re: Curing methods?

Mark,

Yes, I got some 1/32" to 1/64" cracks at the rear of the oven. One of them splits my soldier course--something I was hoping to not see; oh well. One day I may lift the insulation and see what it looks like on the outside.

[Rodneyf]

Re: Curing methods?

I have finished my oven and only have the storage area door and the tiling on top of the stand to do. I have also got my hands on a gas ring and extension pipe ready to start heating up the oven on Friday night, if all goes well I will be eating pizza on Saturday night. I just hope that this method will help to minimize cracking as I have not used fire bricks, all of my bricks are recycled, solid red and 92yrs old. I have put a picture of what each of my bricks looked like when I got them before I cleaned them, it has been quite an exercise to clean each brick but it will be worth it if it all works and I gte good pizzas.

[Gromit]

Re: Curing methods?

Rodney,

Your oven looks fantastic; I love the reclaimed bricks. I feel like I have fought only half the battle with mine. I am baking pizza and bread, but I have NO idea how or when I am going to finish my enclosure. I throw a tarp over it whenever there is not a fire raging inside.

I used your curing method and still got a series of cracks, but I am convinced that it is because I did not take care to lay the bricks on bond in that section of the oven.

Don't rush the cure just to meet a 24 hour Sat. night pizza deadline. Watch for steam escaping the dome. I'm not sure how that will work for you with a waterproof render. If you NEVER see any steam, believe me, that just means it is trapped under the render. My steam started when the dome hit about 300 deg and lasted about 3 hrs. Pay attention to how hot the top of the outside of your dome gets; if it feels really hot, that will give you an indication that steam is still trapped underneath. I have 3 inches of blanket on mine and the top of the outside reaches 120F when the top of my inside domes is 950F.

[Rodneyf]

Re: Curing methods?

Well I have started the cure 28 hrs ago and have decided to go super slow. I have placed a small burner with the the cut off bottom of a gas cylinder upturned above it to deflect the flames heat into the centre of the oven. I started at 4pm and after 24 hrs of burning in an open oven the inside top of the oven reached 98C, I then stacked some bricks in the vent opening and 3hrs later the top had reached 140C and the floor was 75c to 65C near the vent. I am yet to feel any heat on the outside of my render accept right at the joint of the render and the chimney transition. My dome has been finished for a month now and has had plenty of time in the sun and wind to dry so I am hoping this will give me some help in the curing process.

[MK1]

Re: Curing methods?

Rodney,
Looks great! You'll be using the oven in no time. After curing mine and then firing it for the first time, an observation did occur to me. I don't know that it's a problem but the propane burner and the heat beads don't throw much heat out the vent compared to a wood fire. I would suggest your first wood fire should take 4 or 5 hours to get to temperature.My first wood fire was mabe a little excessive, flames shooting out the top of the chimney visible from space.
It stays hot forever with the door closed. On my last firing the temp was 200F 6 days later. I have a 3 day cooking schedule beginning tomorrow, pizza then bread, Boeuf Bourguignon and then ribs. I've been really impressed with the balance of the oven. So far I've never had anything unevenly done, top to bottom.
My metal dome still isn't done, with work and extensive social obligations, (wife and her family), I still have about half my panels to english wheel.

Mark

[Rodneyf]

Re: Curing methods?

It took 56hrs to get the dome up to 370C and the soldier course was at 340C at that time with no cracking at all. I am so relieved that that the oven did what I expected it to do, as soon as the floor hit 300C I had my first pizza in and we cooked another 4 last night during curing. This morning the dome is at 210C, 9hrs after we went to bed and closed the vent with a few bricks. I can see the smoke staining tracking up through the vent the way I expected but I did get a little out the front but not enough to stain the arch.
IT WORKS and the pizzas are the best.

[david s]

Re: Curing methods?

Rodney,
Well done, the time spent eliminating the water is well spent. You will find that your oven will keep on improving in performance (time to reach temp and heat retention) for some months. The best part is that it will encourage you to use it lots.

[Rodneyf]

Re: Curing methods?

David, I had a chance to fire the oven up last week and you are right on the money when you say it will only get better. I now have no heat on the outside top, bottom or sides coming through and the oven is cooking like a dream. The way the cheese bubbles in the centre of the pizza within 2 mins of it going in the oven is just great to watch and even better to eat. I did a 3kg roast leg of lamb the day after with only residual heat and the taste was worth the 7 hr wait.

[david s]

Re: Curing methods?

Rondey,
Try throwing half a handful of hickory chips on the hot coals just before putting in your roast, it's awesome.