Houston We Have a Problem?

[digitalrules]

Our oven works fantastic but I think something went wrong on the final refractory coat. We used a non refractory colorant? Maybe too thin? Maybe too wet? Anybody have any suggestions for a fix? I have started removing the top cracked area. Thanks, Mike
PS. This was my first rookie attempt, started with the Forno Bravo plans.

[Sananguero]

Re: Houston We Have a Problem?

Oh boy, Im just a rookie myself, but that does not look good... you say your last refractory coat was a colorant? Im not sure what you mean, but I will say what I think, given what I have seen, since no one else has...

You probably started with fire brick since your oven works "fantastic". The refractory material you used should have been some kind of mortar to put the bricks together. Your oven is still intact, so you probably used the right refractory mortar as well. After that should be insulation. This is very important for oven efficiency, and so you don't burn any decorative coatings on the outside! If that is a colorant that is flaking off I would continue to peel as much of that stuff oven that you can. Use a steel brush to remove small or hard to remove pieces as well as you can. Then after youve removed as much of that stuff as possible, I would light a raging fire, maybe several, to try and burn out any chemical residue. Bring that baby up to 1000F if you can. Chances are any chemical residue on there is not good for you, remember the brick is your cooking surface and they are porous. Better yet, you should post what you used as a "refractory colorant", to tell for sure. Good luck

Karl

[Les]

Re: Houston We Have a Problem?

Wow - that seems like some serious efflorescence. That can be caused by many things, but you are doing the right thing. Tear it off. Just out of hand, I would say there was way too much lime. I've seen some major cracking in mortar when that was the case (it also causes the efflorescence). What was it applied on top of? The brick or do you have insulation?

[Wiley]

Re: Houston We Have a Problem?

Digitalrules,

So I entered "Chula Vista effloresence" into a Google Search and this is what came up:

http://www.handiworksremodeling.com/...-2010Issue.pdf

Scroll down and page 4 there is a section on effloresence in your area.

Good to know one is not alone.

Wiley

[brickie in oz]

Re: Houston We Have a Problem?

ust out of hand, I would say there was way too much lime.

Lime doesnt cause efflorescence or cracking.

Weve already done this problem in another thread, starting a new thread about your problem wont fix it as Im sure youve had all the good advise available from the members here.

[brickie in oz]

Re: Houston We Have a Problem?

Soak a brick in a shallow container of your tap water and leave it in the sun ( or a hot place, oven etc) to evaporate the water, keep topping up the container, if after a while if you see salt, (efflorescence) then you have your answer.

The common denominator in an oven build is water.

[digitalrules]

Re: Houston We Have a Problem?

I used refractory mortar as a top coat and added the color. I think I am going to insulate with FB blanket, wire it and color coat stucco for a top coat? Thanks for the feed back, Mike

[RTflorida]

Re: Houston We Have a Problem?

Why the colorant BEFORE insulation? Seems to me a waste of product.

RT

[digitalrules]

Re: Houston We Have a Problem?

That was the problem, I never insulated over the brick. I am starting over with insulation.

[dmun]

Re: Houston We Have a Problem?

I am starting over with insulation.

My guess is that if you don't have insulation on top, you don't have any underneath.

[digitalrules]

Re: Houston We Have a Problem?

I have 4" under the floor....?

[Faith In Virginia]

Re: Houston We Have a Problem?

I'm thinking your using the the product in a manor for which it was not intended. Most refractory cements don't act nicely when used as a real thin skim coat. When I built my oven I wiped my interior clean with a wet sponge and the exterior I just swiped over with the trowel and in a short time it developed the same cracking. So I think it's the nature of the product, works great for putting fire bricks together, not so great as a skim coat. If there is not a sufficient bond to the brick and any material shrinkage due to drying you will get that cracking. What is the name of the product you were using?

[digitalrules]

Re: Houston We Have a Problem?

Harbison Walker Refractory mortar....

[dmun]

Re: Houston We Have a Problem?

I have 4" under the floor.

That's great. Usually it's the other way around. Builders skip the under-floor insulation or put it under the slab, and then can't get their ovens up to pizza temps. Glad to hear it, since that's the hard one to re-do.

[Faith In Virginia]

Re: Houston We Have a Problem?

Yup... NO. 36 ???