crock repair

we've got a number of slightly damaged ceramic crocks.  a couple of them don't have any visible cracks, but after trying batches of kraut in them, it's very clear that the cracks are there.  others have visible cracks, and a couple are actually cracked in half.  anybody know how to repair these well enough to use for fermentation?

just to make you all jealous: the 20-gallon crock is entirely sound.

Hi tel,

There are two options that come to mind but it would require firing the crocks again either way. The easiest and safest would be a lead free clear glaze applied right over the original. Anything else that comes to mind that would work and be durable (epoxy etc.) I would not want to use for food production.

Good Luck,

Jeff
 

Japanese lacquer is very, very similar to epoxy, and non-toxic once cured (though it is the same oil that causes poison oak/ivy/sumac reactions, so be careful until it cures!). There are probably other natural options I'm not fully aware of; maybe flax seed oil would be good enough, given enough time to cure.

I think alternating treatments of whitewash and water glass might be worth a shot, if you don't have access to a kiln. This should work in theory, but I have no experience with it: let whitewash soak into the crack thoroughly, let it dry, brush all of it off of the surface, then apply water glass. Both of these are bad for your skin, and you want to wash the water glass off thoroughly before using it for food. That might fix it for the temperatures you'd see in cooking, but the hydrated calcium silicate would probably cause problems in a kiln, because at some high temperature, it will release steam (maybe about a thousand degrees F or so).

Crock cracks are apparent because they leak fermenty liquid on the floor?  A couple of our five gallon crocks have hairline cracks but there's no leakage and no problems with their presence so far as I can tell. 

Beware of "bargain" buys as far as crocks go - usually they aren't going to be useful - as you have apparently discovered.  I did score a $10 lid to our 10 gallon crock because of a chip on one side that does not effect function in any way. 

Officially jealous of your 20 gallon monster crock.  Not so jealous of very very carefully moving it around, though.    Do you make kraut in it in when it's already in its final resting place?  I can't imagine budging it when full with cabbage or anything. 

I'm interested in the lacquer option.  will it bond well with the glaze?  is that sort of lacquer widely available?  what temperatures and times are involved in curing it?

if I knew somebody with a kiln, I would probably go the re-glazing route, but I don't.  maybe I should try to make more friends.

marina phillips wrote:
Officially jealous of your 20 gallon monster crock.  Not so jealous of very very carefully moving it around, though.     Do you make kraut in it in when it's already in its final resting place?  I can't imagine budging it when full with cabbage or anything. 

I haven't personally used the big crock yet.  when I dug it out of the barn last year, I didn't have a lid.  my dad built me a great cedar lid last Fall, so now I'm just waiting for the weather to warm up to do a giant batch of miso.  and yeah, I'll just put it in place before filling it up.

that crock, and most of the others I've got, belonged to my great great grandmother.  she used the big one to make suolakala (salt fish).  fishermen would drop off a salmon occasionally in exchange for access to a snack of the finished product whenever they were hungry.  now I'm getting all nostalgic, and I wasn't even there.

It's awesome you're bringing those family heirlooms back into everyday use, tel. 

If I remember correctly, reglazing in a kiln could fix the cracks or make them a lot worse.  There's a great deal of expansion and contraction that goes on during a firing, and I think you'd run the risk of breaking them apart entirely.....

What about hot food safe wax smoothed into the cracks?  You'd have to keep the crocks at a stable and fairly cool temperature, but seems that could work.  Maybe. 

marina phillips wrote:
It's awesome you're bringing those family heirlooms back into everyday use, tel. 

If I remember correctly, reglazing in a kiln could fix the cracks or make them a lot worse.  There's a great deal of expansion and contraction that goes on during a firing, and I think you'd run the risk of breaking them apart entirely.....

What about hot food safe wax smoothed into the cracks?  You'd have to keep the crocks at a stable and fairly cool temperature, but seems that could work.  Maybe.   

I've put the word out that I'm looking for some kiln access and expert advice.  if I find somebody to help me, I might start with one of the crocks that's in worse condition as a test run, then move on to the more intact crocks if it goes well.

wax was actually my first thought.  I generally pack miso in while it's still warm, but not more than 80 Fahrenheit.  miso definitely finishes faster if it gets a little warm over the summer, but I could probably find wax that would remain solid.  do salt and acidity cause any problems with wax?

Uhurisol cures at room temperature or a little warmer, by absorbing moisture. In that regard, it bears more resemblance to superglue (cyanoacrylate) or silicone.

I think the raw uhurisol-bearing sap is an agricultural/artisanal product, not commercially available. You'd have to ship it fairly quickly, and widespread allergies make handling problematic. The best bet might be finding someone with a mature vine of the right species, and tapping the sap yourself.

I'm now leaning more toward flax seed oil, or other edible drying oils like walnut, safflower, etc. If wax might work, these are much more likely to.

drying oils sound very doable.  I've got some pure (pure-ish, anyway) tung oil hanging around that I briefly considered using, but I think an edible oil would probably be a better option.  and tung oil takes ages to cure.

so, you think several thin layers of a drying oil over the entire interior surface?

I might like to plant a lacquer tree (Toxicodendron vernicifluum) for future use, though.  sounds like useful stuff, urushiol does.  and nasty.

I'm curious if you ever managed to get your crock to not leak. I have one with a hairline crack that I'd love to be making sauerkraut in but it makes a mess when you put liquid in it. I've lined it with a bag in the past but it's a pain.

keco86 wrote:
I'm curious if you ever managed to get your crock to not leak. I have one with a hairline crack that I'd love to be making sauerkraut in but it makes a mess when you put liquid in it. I've lined it with a bag in the past but it's a pain.

I haven't actually tried yet.  all manner of other projects intervened.  it is certainly still something I plan to do at some point.

I think the drying oil idea is pretty solid, though.  toss up between walnut oil and flax oil for me.  seems like either one should work.

after any leaks are repaired, the next issue will be to keep the crack from re-opening or spreading.  I'm leaning toward cyanoacrylate on the outside of the crock where it won't contact the contents.

please do post about any repairs you try.

tel jetson wrote:
drying oils sound very doable.  I've got some pure (pure-ish, anyway) tung oil hanging around that I briefly considered using, but I think an edible oil would probably be a better option.  and tung oil takes ages to cure.

so, you think several thin layers of a drying oil over the entire interior surface?

I might like to plant a lacquer tree (Toxicodendron vernicifluum) for future use, though.  sounds like useful stuff, urushiol does.  and nasty.

Pure Tung Oil can be found at the Real Milk Paint Company.  It is absolutely 100% Tung Oil.  They have two grades.  The really thick stuff dries very hard.  The Thinner version does also but for mending cracks I would try the thick version.

I tried mending two cracked crock (not 20 gals. LOL) but it made the crack worse on one and the other literally turned into a pile of rubble on the bottom of the kiln.  My potter friend warned me in advance.  There are a few potters here in this area so re-firing "stuff" isn't a problem.  Dealing with artists is much easier than someone that is only a business owner in my opinion.  I hope that you can solve the problem.
Peace.

I added a few layers of tung oil and let them dry on some cracked crocks. I however I found some troubling info regarding tung oil perhaps being poisonous:

http://www.ehow.com/facts_5561688_tung-oil-safe.html

Seems it is fine for a wood finish, but I wonder whether fermentation conditions would corrode it and let the poison loose. I think I'm going to try to scrub off the tung oil and try again with walnut or flax. Does anyone know any other hard-drying food oils?

Dave Bennett wrote:

There are a few potters here in this area so re-firing "stuff" isn't a problem.  Dealing with artists is much easier than someone that is only a business owner in my opinion.  I hope that you can solve the problem.
Peace.

I'm a potter and want to make some crocks. If you get the chance and want to post some images of the crocks you like best that would be really helpful. I'll do an image search for ideas but it would be interesting to hear from a few users as to size and any other details or requirements (type of clay or glazes etc.) that would make it more useful.

I also have a cracked crock! Has anybody figured out the best way to repair them?

I have found this video, where the person is using beeswax: