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bturton 12-21-2008 02:37 PM

My oven looks like a Chia Pet
Hmmm, so it was a little disturbing today when we went out to add a couple courses to our oven to find that it had grown kind of a fur. How disturbed should I be about this? Its kind of white and fuzzy. Is this a moisture issue or have I built on a toxic waste site? We've been using Heatstop 50. The weather has been pretty nice, no freezing. We've kept it covered...
This is probably addressed somewhere else in the forum. Hopefully someone else has come across this before. If anyone can point me in the direction of that thread I would appreciate it.
Merry Christmas everyone!

Archena 12-21-2008 04:24 PM

Re: My oven looks like a Chia Pet

What is your oven made of? What you're describing sounds a lot like the leaching you see on concrete blocks, especially in basements, down here. If that's what it is you have a water problem. Water is seeping through the brick, driving out salt. If it looks like cotton and is mildly gritty, that's probably what it is.

It's kind of hard to imagine how that could happen to an oven, though. Could you post a pic or two? It would be helpful to see the oven. On the bright side, if it is leaching, is not anything you need to panic about yet. Thoroughly drying the oven or applying a sealant should stop the problem.

Edit: I should’ve read more carefully. Are you noticing it mostly on the mortar? It sounds very much like you do have a moisture problem. The tarp is probably aggravating the heck out of it too. It’s normal for moisture to have to leech out of the mortar, but if moisture builds up on one side it has a tendency to push salt out the other. That’s why you usually see it on basement walls. Instead of keeping the oven dry the tarp is probably allowing moisture to build up in between it and the oven. At the very least, it may be interfering with airflow.

It’s an easy fix, assuming I’m right. Find a way to raise the tarp up off of the oven so that it doesn’t actually touch the oven. That should allow it to dry normally, and stop the leaching.

bturton 12-21-2008 05:11 PM

Re: My oven looks like a Chia Pet
1 Attachment(s)
Sounds like leeching I guess. Here's a pic with the fur. I'm not sure what to do when the weather won't cooperate. We started in on Thanksgiving and have had a couple cold snaps. Ah - I see you're in Alabama, so probably similar weather. Thanks for the input!

Archena 12-21-2008 05:32 PM

Re: My oven looks like a Chia Pet

No problem. Glad to help. There’s a reason they don’t usually build houses in the middle of winter down here. May not be that cold, but boy, will it get wet. I do remember the guys rushing to get all the concrete work done before winter set in when we were building our house. Don’t worry though, spring comes pretty early.

Yeah, when I noticed you are in Georgia that's what made me think of it. My parents built a house on Lake Martin years ago and the basement always had that problem.

Just looking at the pic, it looks like your brick is probably moist and it's coming out of the mortar that is covering the brick. It'll probably dry okay this summer, but if it keeps up, you may want to scrape the excess mortar off. From the direction it's coming out the moisture buildup is between the brick and mortar. On the bright side, it shouldn't be very hard to scrape off.

The only bad thing I can think of that might happen is that as you cure the oven the moisture may push the mortar off. It shouldn't actually damage the oven at all. But if you're planning to coat it with anything you need to get that dealt with before you put on the coating. Otherwise it will just peel off.

As for the stuff that's on it now, you can just take a brush and knock it off. It's really easy to clean. The hard part is to keep it from doing it again.

Frances 12-22-2008 05:42 AM

Re: My oven looks like a Chia Pet
This link should help, looks just like what you've got:

Efflorescence - Wikipedia, the free encyclopedia

I don't think you need to worry at all.

However, the dome needs to be kept covered and hydrated until it cures, so leave the tarp on! You will be insulating over the top of the oven anyway, so don't worry about cleaning the efflorescence off. And the insulation does not need to bond with the surface of the oven dome either.

As I understand it, the only worrying thing about efflorescence would be if you don't know where the water is coming from (say a leak in a cellar). You know exactly where its coming from - the moisture in your mortar, which is just as it should be. That moisture will all be driven off (with a vengance!) when you cure the oven. Just keep going, you're doing fine!

RTflorida 12-22-2008 09:13 AM

Re: My oven looks like a Chia Pet
My two cents.......How long has the tarp been on and are you wrapping the dome?
Although all cement based products need to retain moisture and cure slowly for about a week, they should never be covered tightly with plastic or a nylon/polyester tarp. You want to retain moisture and allow slow evaporation...not stop the evaporation entirely. You need to leave a bit of air between the tarp and dome...the same is true for concrete slabs. I'm guessing this "growth", although it appears to be mineral based and not a mold/mildew, may be caused by too much moisture retention much like mold/mildew.


bturton 12-23-2008 08:25 PM

Re: My oven looks like a Chia Pet
Thanks guys. The tarp has been on the oven probably 75% of the nights - so maybe 20 out of 28 days. If there was any chance of rain we covered it. There were about three days when it rained continuously - That's the longest period that it didn't see daylight. We made supports to keep the weight of the tarp off the oven while the mortar was drying - so it was pretty loose - the tarp wasn't really touching it.
Don't think we'll get much done for the next couple days. I would however like to get it closed in the weekend. If its still standing when we remove the support from the inside we'll see if the curing process won't take care of the fuzz..
Isn't it odd that my oven has actually grown better than any of the chia pets I got as a child?

Archena 12-24-2008 05:13 AM

Re: My oven looks like a Chia Pet
Well, technically you’re growing one of those Mineral Garden things. I wonder what would happen if you added food color?

Of course, if it keeps raining, you can throw in some Sea Monkeys…

(I know, seventies fads aren’t complete without Pet Rocks, but I thought it had enough bad 70s references as it is. :D )

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