How cracked is too cracked?

Help, my rocket stove got attacked by pigs!  It’s a long story. Short version, do I have to take it to the vet or can I repair it?

It’s kinda a long shot but I have a sentimental attachment to Thoor Ballilee II, my rocket stove. It is/was a Walker rocket core. Prior to being abused by pigs it was out in all kinds of weather, and I was not the best caretaker. But now I think I can do better, plus I have cob.

Will cracks in the ceramic fiberboard be a big problem? If so would adding some con or some clay-sand mortar there help or make it worse?  

Pictures of broken fiberboard and also firebrick. Same question regarding the forebrick.

Hi Josh;
Dang piggies!
In my opinion, any broken/cracked CFB needs to be replaced.
The cracked firebrick could be repaired using an automotive exhaust repair paste.
However, I would just replace them at the same time as the CFB.

So, isn't it about Pork Chop time???

Thanks Thomas.

Can you expand a bit?  I'm really wanting to save the patient and willing to do heroic measures.  Just nothing toxic.  Automotive exhaust repair paste sounds like it might be, so I will try the cob or sand-clay for the moment till I can get a replacement brick.  

As for the ceramic fiberboard, I do have one extra piece from a different project that can patch up the worst hole.  It will result in a bit of a cyclone shape.  

What happens when there are cracks patched with cob? or with cob around them?  Assuming it's airtight enough smoke can't penetrate, is it simply losing some efficiency?  My rocket mass heater has "cracks" where the cleanout gate slides in and out, and I patch that with some aluminum, and the thing works OK but not great--however I assumed that was for all hte other reasons that the Code imposes on the design.

thomas rubino wrote:Hi Josh;
Dang piggies!
In my opinion, any broken/cracked CFB needs to be replaced.
The cracked firebrick could be repaired using an automotive exhaust repair paste.
However, I would just replace them at the same time as the CFB.

So, isn't it about Pork Chop time???

ps the pigs are no longer with us

I have stuck ceramic fibre board back together with the "glue" they sell for replacing door seals on wood stoves. the fibreglass rope stuff. I am sure it is just sodium silicate.

Hi Joshua, if you are worried about things being toxic then be very careful handling the ceramic fiber.
Once the product  has been heated it can become fragile and dusty, that dust is toxic and potentially carcinogenic.
At the very least wear a mask while handling it.

Thanks team.

I have not found any wood glue that is pure sodium silicate.  Any brand recommendations? I could order some from a lab supplies place but it won't arrive before the work day (Saturday).

Oops--wood stove glue, not wood glue.  I'll try another search engine

Joshua Myrvaagnes wrote:Thanks team.

I have not found any wood glue that is pure sodium silicate.  Any brand recommendations? I could order some from a lab supplies place but it won't arrive before the work day (Saturday).

You should be able to buy  adhesive from the same place you bough you ceramic fiber?
Any stove shop will have high temp adhesive, most are clay based and cheap to purchase in a mastic gun tube size, my supplier has lots on offer like stove pipe sealer, water glass based glues and purpose ceramic fiber glues.
All of them set rock hard with no give or movement, so not particularly good for most jobs, as a rule refractory products crack or break because there is no room for expansion so adhesives that set hard dont always work very well.
However ceramic fibre is not so prone to expansion but it does become brittle and weak and crumbly once heated.

You might get the best results by simply pushing the parts together without any glue but of course without actually handling the piece it is difficult for me to say!

I live near France but but mainly but from the UK, this is the sort of stuff you want…..

update--I ignored everyone's good advice to start over and to buy a ceramic adhesive, and just using cob got the thing cobbled together again. It works pretty darn well, though it smokes a bit sometimes.  I need to finish the cob all the way to the top up a few more inches, but it often flames so high it's going up the sides of the pot.  It also melted the handle of the instant pot lid when I put that on there with lid to reheat something...which I will put on my long list of Joshua's mistakes