Evaluating old crocks and their suitability for food uses

When I do garage sales, I am always looking for specific things I need but cannot afford. When it comes to things I want but do not immediately need, I try to keep a handle on my hoarder tendencies by restricting myself to items of good construction and materials (usually that means antique or old-fashioned) that will be useful as tools for more sustainable living. The test: "If I don't need this right now, will I be damned glad I bought it, after the Zombie Apocalypse?"

Today one of my purchases under the ZA test was a $3 one-gallon earthenware crock, of the general type useful for sourdough starter or making fermented foods:



It's in good condition, a few tiny chips in the exterior glaze but otherwise very sound-looking. It has absolutely no stamps or markings inside or out.

I don't actually do any fermentation now, and there's a good chance I'll just put this crock on my counter and use it to store cooking spoons in. But I'm aware of controversy and uncertainty in many quarters about whether (or which) old crocks are safe for food use. There are issues of condition (mine has some tiny chips in the exterior glaze but appears entirely sound) and food safety (specifically with regard to potential metals in the glaze) and perhaps stuff I'm unaware of. I've done searches here on permies and found tangential references to these issues, but nothing really specific.

My question is, are there rules of thumb for evaluating old crocks? Are there ways to discern age, geographical origin, maker, glaze type, or likelihood of unwelcome heavy metals, perhaps by shape, color, glazing style, et cetera? Is a "salt glaze" an indicator of safety as some say, and how do you tell if that's what you've got? What are things y'all look for if and when you consider buying a used crock?

I won't regret this purchase in any case because, you know, three dollars! But I realized it might be smart to know more for the next time I spot a crock "bargain".

I know y'all well enough to know that some of you take a precautionary stance with regard to food toxins that is greatly more cautious than my own stance. I suspect that "I won't use any crock unless I don't know for certain sure it has a modern lead-free glaze" is a position that might be shared here. At the end of the day I don't think it's likely to become my position, but I am interested in knowing as much as possible about how to tell (guess, predict, speculate informedly) in cases where the matter is uncertain.

Old crocks. Evaluating them. Go!

BEAUTIFUL crock.

My question is, are there rules of thumb for evaluating old crocks? Are there ways to discern age, geographical origin, maker, glaze type, or likelihood of unwelcome heavy metals, perhaps by shape, color, glazing style, et cetera? Is a "salt glaze" an indicator of safety as some say, and how do you tell if that's what you've got? What are things y'all look for if and when you consider buying a used crock?

I've found this to be a very muddy issue too. I've done a lot of reading, researching, testing, talking to pottery makers and food experts - and I'm still confused on many points. But I'll share what I've learned, and some experiences, maybe you'll find something useful.

First, age and location are only general guidelines to think about when it comes to food safety. There are still many pottery crocks being made today with heavy metals in the glaze that can leach into food.

There are apparently kits that you can buy to test for lead and other heavy metals in pottery. I haven't tried one yet.

There are rules of thumb for evaluating old crocks, but I don't know many of them. A lot of it had to do with the shape and the composition of the clay, style of painting, &c. I've seen books on this at the library at our local University. Antique dealers may have a good reference on the topic.

If memory serves, some colours of glaze are more likely to have problematic heavy metals. Yellow was... I think... cadmium. White can contain lead. This is going from what a person at the pottery studio told me, and I can't confirm it's correct. Hopefully someone else will chime in on this one.

What I look for when buying an old crock is how beautiful it is to me. Would I be happy to keep it if I couldn't use it for food? The ability to hold water is my next big thing to look at. Even without obvious cracks, some crocks leek. I've had one seep water through the tiny cracks in the glaze and out the bottom, slowly so you would hardly notice, but still, not good.

I don't know salt glaze, so I can't help there.


One thought I've had, is that cooking and fermenting are very different. Different temperatures, chemical reactions, &c and so on. I've often wondered why we don't have different criteria for evaluating the food safe nature of a crock for cooking vs fermenting.

A fermenting pot with cracks and chips on the inside is undesirable, in my experience, as it can harbour invisible beasties (both good and bad) that will alter your ferment. This may be perfect if you are using wild yeast to make a beer or mead. But most of the time, it makes the flavour of the ferment unpleasant, or causes early spoilage of the contents. One way to get around this, is to line the crock with a heavy plastic bag, but I don't usually do this as I don't like plastic touching most of my fermented foods. I do, however do this with long fermented miso as I've seen many Japanese people use it.


I'm looking forward to what other people have to say.

I also didn't know what to think, so here is what I decided. I really wanted to start fermenting things, so I wanted to start with stuff I knew would be ok. I looked on Craigslist, and most of the crocks cost more than new. I was worried about lead with all of them. The only difference in price was the shipping. Sandor Katz recommended Ace hardware's deal with Ohio Stoneware crocks, American made, new, lead free, and shipping is free if it goes to your local Ace Hardware. I bought a 5 gallon, which I am very happy with, particularly during the cold half of the year. Also glass is pretty worry free as far as I know. I have found glass containers at garage sales, in which I could find little tiny bowls that fit perfectly in the lid so that there as an exact water barrier of like 3mm, to keep mold/yeast out. Also, I bought a Polish crock from a company and it has a water seal and it was only about $70 bucks for a one gallon, which I thought was a good deal. I have no financial interest in any of the companies, just trying to get a good lead free deal.

A lot of the deal about buy it just in case, is how much room you have. Do you live in San Francisco or out in the country? Rents and space are very different. I like your framework Dan. Am I going to regret buying it or not buying it (whether or not the inevitable zombie apocalypse happens within the next few weeks.)
John S
PDX OR

I get crock-pot crocks from the dump. They should be new enough to not have lead issues. They're only 1 gallon, but the price is good.

They made old crocks of the best materials they had back then but it isn't ideal.
Glass is a far superior material for this task.

Dan Huisjen wrote:I get crock-pot crocks from the dump. They should be new enough to not have lead issues. They're only 1 gallon, but the price is good.

I don't ferment , but I bake using the jim lahey no knead bread method. When I was doing 10 loafs at a time I found that the cast iron Dutch ovens that were the proscribed baking container were too expensive and bulky. I turned to the removable linings of junk store crockpots. They worked great, but they were hard to find, so I bought a crockpot with a non removable crock and broke it open. Same damn crock less some outside glazing.
These guys are cheap and indestructible. With the right glass plates as lids they stack even while full.
I now use stainless steel steam table pans, mostly because you can fit more rectangles than circles in a given oven.
I don't see stainless steel being promoted for ferments, are the brines too harsh? Walmart sells a nesting set of thin walled stainless steel stock pots for their usual price of cheap. I may use one for a bucket rocket stove one day, they are more thermally resistant than a plastic bucket...

I have heard that depending what you are going to do with it, you can line crocks with beeswax as a protective coating. Would work good for kraut, or also for a leaky crock you want to seal up. heat would obviously be a no no.

We're all looking for something economical for fermenting.
I've been developing and testing a system for quite a while. Much better than old crocks with plates that don't fit well and rocks or jars for weights. I expect to be able to supply this system soon.
1. Glass for the main body. Any cracks are immediately apparent, there's no place for nasty bacteria to hide and it's easy to monitor the fluid level.
2. Proper ceramic weight.
3. Tight fitting lid to keep evaporation to a minimum.