Steady good heat without the large flames. How?

[V-wiz]

Re: Steady good heat without the large flames. How?

Good luck, I've found crack repairs to never be particularly successful. But you'll need to get some moisture back into the crack before attempting a repair. Try making a thin slurry of pure calcium aluminate cement and get it onto the mating surfaces after the water, then fill with your heatstop.

I'm an advocate of curing t he oven after insulation because if the dome is uncovered there is a huge temperature difference between the inside temp and the outside temp which may have bee n the cause of your cracks.
What was the outside ambient temperature at the time you were firing?

Looking at the first photo on this thread it seems as though you have a lot of coinciding vertical joints, this could also be a contributor.

Thanks David, since ive already purchased the Fireplace cement that is meant to fill cracks and repair damages ill use that, it does contain Cal-Sil. At the lower temps of curing the oven was just warm to the touch on the outside, however yesterday it go nice and warm.

You are right some bricks do have coinciding vertical joints.

[david s]

Re: Steady good heat without the large flames. How?

Good luck, I've found crack repairs to never be particularly successful. But you'll need to get some moisture back into the crack before attempting a repair. Try making a thin slurry of pure calcium aluminate cement and get it onto the mating surfaces after the water, then fill with your heatstop.

I'm an advocate of curing t he oven after insulation because if the dome is uncovered there is a huge temperature difference between the inside temp and the outside temp which may have bee n the cause of your cracks.
What was the outside ambient temperature at the time you were firing?

Looking at the first photo on this thread it seems as though you have a lot of coinciding vertical joints, this could also be a contributor.

[V-wiz]

Re: Steady good heat without the large flames. How?

Thats what i was thinking. I just purchased Rutland fireplace mortar, it says for repairing cracked and chipped firebrick and repoint mortar joints. Also good for 2000f. Its basically what i want to do. So ill widen the cracks and fill it in.

[SCChris]

Re: Steady good heat without the large flames. How?

I'd fill it when it's tight rather than wide, I wouldn't want to create a wedge that makes things worse.. Tscarsborough, would be my go to on this.

Chris

[V-wiz]

Re: Steady good heat without the large flames. How?

Should i heat it up for the crack to expand then fill the crack? Or grind out the crack to widen it then fill the crack? Thanks

[SCChris]

Re: Steady good heat without the large flames. How?

I think your render mix should be fine.

Best to you.

Chris

[V-wiz]

Re: Steady good heat without the large flames. How?

Thanks Chris, i will fix the cracks this weekend and insulate permanently, any special mortar i should use to fill the cracks?

[SCChris]

Re: Steady good heat without the large flames. How?

V-wiz, have you insulated?
Here is where I'm headed.. Whatever you do to patch the cracks will not be structural or at least not very. I think I'd mix a small batch of render, just enough to fill these cracks. Insulate the dome with your blanketing start working on the finishing of the igloo or house. The insulation will not burn and it will stop these cracks from venting. The other thing it will do for you is to even out the dome temps and so minimize the stresses that promote cracking.

My opinion is that once you start curing above 250F there are advantages for loosely covering the dome with insulation. One of these advantages is promoting a more even heating of the dome and so minimizing cracking. This is my opinion and it's just theory... and you're far past 250F and your dome is ready to cook, so no matter what you need to insulate and weatherize..



Thanks

Chris

[V-wiz]

Re: Steady good heat without the large flames. How?

May i add that ive been heating it up gradually, not very slow but fairly slow, i had fire in there for about 4 hours.

[V-wiz]

Re: Steady good heat without the large flames. How?

And the crack where you can see through

[V-wiz]

Re: Steady good heat without the large flames. How?

I did my last cure fire today, got up to 750-770F. Cracks appeared to have gotten wider, and now i can see through the crack at one area. I can see the fire ever so slightly, Structurally i guess it will be okay and i know it will still function as it should. My question is how do i repair it and what is the best way? Heat it up, have the cracks open up, grind out the cracks, widen the cracks and fill the cracks back in?. Now what do i use? Heatstop50? Rutland cement? Rutland gasket cement?. I have a bottle of the Rutland gasket cement which is good for 2000F, however i dont think that will be safe for food. I would really appreciate the help guys.


Here is the widest cracks



Here is the area of the largest crack going down to the floor.



Opposite side of the dome.

[david s]

Re: Steady good heat without the large flames. How?

Remember that cracks are to be expected even when you try to avoid them. At 800 most of your curing is finished and you can enjoy your first pizzas with friends.

Regarding curing as a point of reference, when I started looking into a WFO the methodology for curing was to build a small fire and get to temp and stop.. The following days increasing temps by 100F every fire until 800 or so and at this point the formal curing was finished. What I don't like about this method is that there is a lot more to the oven than the interior surface temp. It's my opinion that more effective curing can be done with less cracking if the oven can be brought to a temp and held at this temp for an extended time. I feel that these extended periods of controlled heating minimize the heat stress on the oven.

Ideally, in my mind, the heat during curing would build at a slow rate to expose the exterior side of the bricks to higher temps that facilitate drying. Substantially extending curing fires isn't fully realistic in most cases. The problem is the control of the heat source over the extended time.

• Firstly when you use wood to cure each branch is a bit different so the caloric content is different.
• Secondly the ability to focus on a fire and maintain a fire for extended periods is tough.
• Third the reaction of the oven to the heat changes, continually, throughout the curing.

Examples of the temperatures running well past the target are more than common because the oven becomes more dynamic, more alive, as it cures.

Enjoy your oven!!

Chris

I agree with you Chris. The recommended method for driving the water out of new kilns and castable refractory is a slow continual rise in temp. However the problem of doing this in a WFO is that if using wood fire the direct impingement particularly on the top of the dome creates uneven temperatures and to exacerbate this, as you mentioned previously, the water lower down holds the temperature back. Allowing the oven to cool down brings all the refractory back to the same temperature so the heating can begin again allowing the temperature difference to be much closer. There may also be some migration of water from the wet parts of the oven to the dry parts as the oven is allowed to cool, although in 24hrs I'd guess this would be fairly minimal. It could however be of an advantage if it were left longer, say two or three days between firings.trouble is at this stage you are so excited to get the oven dry and cooking, who can bear to wait more time.

[V-wiz]

Re: Steady good heat without the large flames. How?

Good info Chris thank you.

[SCChris]

Re: Steady good heat without the large flames. How?

Remember that cracks are to be expected even when you try to avoid them. At 800 most of your curing is finished and you can enjoy your first pizzas with friends.

Regarding curing as a point of reference, when I started looking into a WFO the methodology for curing was to build a small fire and get to temp and stop.. The following days increasing temps by 100F every fire until 800 or so and at this point the formal curing was finished. What I don't like about this method is that there is a lot more to the oven than the interior surface temp. It's my opinion that more effective curing can be done with less cracking if the oven can be brought to a temp and held at this temp for an extended time. I feel that these extended periods of controlled heating minimize the heat stress on the oven.

Ideally, in my mind, the heat during curing would build at a slow rate to expose the exterior side of the bricks to higher temps that facilitate drying. Substantially extending curing fires isn't fully realistic in most cases. The problem is the control of the heat source over the extended time.

• Firstly when you use wood to cure each branch is a bit different so the caloric content is different.
• Secondly the ability to focus on a fire and maintain a fire for extended periods is tough.
• Third the reaction of the oven to the heat changes, continually, throughout the curing.

Examples of the temperatures running well past the target are more than common because the oven becomes more dynamic, more alive, as it cures.

Enjoy your oven!!

Chris

[V-wiz]

Re: Steady good heat without the large flames. How?

Thanks Chris, im pretty sure the oven is dry, it was sitting under our Socal heat for a whole month before putting fire inside. But i will get to 800f and try to keep it longer. I hope the oven doesnt crack anymore.