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pzachef 10-18-2010 10:47 AM

Whats the latest in crack repairing
My small crack in my outer arch now runs across the dome about half way down the back. The arch portion opens enough to slip a quarter in. It continues thru the top left side of my vent and then through my inner arch, although does not open up so much. The dome however opens up enough for me to see some smoke comming out. I noticed this last night near the center during my 700 degree curing fire. 800 degree and final curing will be tonight, then I need a plan to do my fixing.
I've heard some people using RUTLAND furnace cement across their domes and fireplace mortar for whats visible. However, I noticed mixed results due to the heat curing requuired for the products. A post from someone in Hawaii had good luck by filling cracks while firing the oven and torching the exposed areas from the outside. Sorry I didn't save the url to post the link to that post here.

Also, I added about 3/8 inch of heatstop to the outside of my dome when building so, I'm hoping the line I see outside matches through to the portion leaking in the dome.

Feedback please....

thamnophis 10-18-2010 06:43 PM

Re: Whats the latest in crack repairing
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I'm wondering the same thing. I had mortar separate from the brick (which is a type of crack I suppose).

There is a high temp caulk available, but don't know if its appropriate. I also wondered is it changes the nature of HeatStop50 (for example) if one mixes it very wet and uses it to "flow" into the cracks.

I was reading a brochure from a wood fired oven company that stated "cracks *will* appear"... Made me feel a little better...

pzachef 10-18-2010 06:52 PM

Re: Whats the latest in crack repairing
I posted a thread about my cracking when it first began at my 400 degree curing fire ad I felt better as if I now made it into an exclusive club of others just like me.
However, since there is some differences of opinion in the posts I read about fixing cracks, I thought I would solicit the latest opinions or experiences in crack repair but, no replies to that yet.
Stay tuned.

follow link below to the beggining of my cracking.

Tscarborough 10-18-2010 06:58 PM

Re: Whats the latest in crack repairing
As a rule, if the crack includes cracking through the brick, it is structural. If the crack is only though the mortar joints, it is a shrinkage/thermal crack. You can not mortar over a crack to repair it, it will simply mirror through. Nor can you fill in the gap, it will be too narrow and will just re-crack.

The options are to grind out the joints to at least a 1/4" (but more is better in this instance, 3/8" being the sweet spot) and re-mortar it or ignore it. The depth of the grind should be at least the width. For a joint leaking smoke it is probably better to repair it if possible.

Mix the repair mortar somewhat dry, basically to what is called "dry-pack". Just damp enough to from a ball in your hand when you squeeze it.

pzachef 10-19-2010 05:33 AM

Re: Whats the latest in crack repairing
2 Attachment(s)
Did my 800 degree burn last night with no new developments. My hope is that the surface cracks on the outside follow whatever cracking is leaking near the dome top so where I need to fix is straight forward.
What's your opinion on the Rutland fireplace and furnace repair products that are heat cured in place?

ThermoJax 10-19-2010 06:10 AM

Re: Whats the latest in crack repairing
If you have to grind it out, I can personally recommend the harbor freight multi purpose tool, with the diamond blade. Easy to work with, able to get right into the joint and grind it out. After my soldier course was in for a day, I saw some cracks and ground them out and remortared. I also did some inside the oven after closing up. Works well in tight spaces.

Good luck


thamnophis 10-19-2010 12:54 PM

Re: Whats the latest in crack repairing
I wonder - if the cracks are caused from thermal expansion might the cracks just be forced to reappear, there or elsewhere?

I noticed mine open when firing, close when it cools down.

pzachef 10-19-2010 05:07 PM

Re: Whats the latest in crack repairing
I did a closer inspection tonight, I think whatever cracking I can see from the inside matches the visible crack line on the outside. I saw a couple of places where the crack goes right through the center of a brick.
I spoke to a Rep at the RUTLAND company today and got fixing advice. He told me not to try the heat cure products at all and use castabl refractory cement after grinding or notching out the cracks. And to grind out the mortar in my affected arch joint and use the castable cement there as well.

Tscarborough 10-19-2010 05:31 PM

Re: Whats the latest in crack repairing
Cracks through the center of a brick may be structural. Can you take a pic of the inside?

pzachef 10-19-2010 06:59 PM

Re: Whats the latest in crack repairing
I will take some and post them after dinner tomorrow night.

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