Curing methods? Firing Your Oven Discuss Curing methods? in the Oven Management forums; Mark, What was the indication that you had driven off the moisture after 30 hours? Was it steaming the entire ...

[Gromit]

Mark,

What was the indication that you had driven off the moisture after 30 hours? Was it steaming the entire while?

[MK1]

David,
I never had any steam from the inside of the oven. I have a stainless vapor barrier on the outside of the masonry, under the insulation. The vapor, (I hesitate to call it steam because it wasn't hot) came from the joint I have between the stainless and the chimney,(not finished). The vapor started after about 3-4 hours of temps at 400F. It steamed steadily for 26-27 hours and then just stopped. That's when I started with the charcoal.

Mark



PS I just looked at your build again, (haven't for a little while) and I think it's fantastic, particularly the vent to pipe transition. Shame to cover it! I do think the oven should be cured like a giant piece of pottery.
After seeing my sons bread evenly done on all sides, realizing how well balanced the dome charge is to the thickness of the floor I have to suppose "The James Gang" has been through all this before and have perhaps found it's a waste of time.
I just wonder if I'll get some cracking when I fire with wood.

[Rodneyf]

I am so glad you have no cracking and can't see why it would crack now. The way you went about it looks good and I don't have a burner so I think I will stick to the beads. How long did your dome take to build, how long did you leave it before you cured it and what temperature was it during the time between the brick work completion and the curing fire. I am trying to compare your drying times with mine, we are going through a dry period right now and the daytime temps are around 19C but we are down to around 4C overnight. Lets see some pics of the bread next and thanks for for the update.

[MK1]

I started almost 3 months ago, was about half complete right away, got busy with work and then finished about 2 weeks before the curing fire. It's been in the 80s F and humid most of the time, 60s at night.
Have your source of beads at hand. Without a burner you might need 200lbs. Pics on the way.

Mark

[Rodneyf]

That is a lot of beads! I don't know if I want to spend the $130 on beads yet so I might see if I can get a burner. My dome will have been drying for 4 weeks by the time I start my fires so it may have dried quite a bit in that time. The temps here have been pretty good this week and the WFO has been uncovered all day every day in full sun with a bit of wind around so it must be drying well. I have done a dry fit on the chimney and will finish all the brick work tomorrow then fit the insulation and render the week after.

[MK1]

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]

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]

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]

Originally Posted by MK1

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]

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