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Fermenting is a science, and a bit of an art. It requires care in a few specific things, but doing it right is not particularly complicated. We provide instructions that are accurate to the best of our knowledge, and which are based on the methods we successfully practice ourselves. There are no guarantees of success or safety with fermented foods. While properly fermented foods are not only safe, but healthy to eat, it is up to you to follow instructions to ensure safety, and to trust your eyes and nose, and don't eat things that do not look or smell like food. We offer no guarantees of success with our product. We do warrant that it is as described, and will do what we say it will, but how you use it is your choice.

Homemade kraut is one of the simplest fermented foods, but it follows slightly different rules than other fermented foods, because it involves only a single vegetable (usually, though it can involve more), and because it does not require a separate brine.

To make kraut, you slice or chop the cabbage. Size of the pieces is irrelevant, they may be any size you prefer. Most people go for something a little larger than coleslaw.

The short version is that the cabbage is packed into jars, and salted (or salted then packed into jars), and weighted down so the juice is pressed up around the cabbage to cover it.

Tip #1: Kraut requires HEAVIER WEIGHTS than many other ferments. When we make kraut, we use about 4-5 of our standard square weights, on top of a dunker extender to press the cabbage down.

But… The cabbage will not produce enough brine to cover the cabbage right away. It can take a day or so for this to happen. That is NORMAL.

Since it does not call for a separate brine, there are various methods for getting the cabbage to produce enough liquid to cover the cabbage. A frequently recommended method is pounding it, either in a bowl, or as you put it into the jars.

Tip #2: Don’t pound the cabbage. For the very best kraut, do not pound the cabbage either prior to packing it, or during packing. You get a crisper texture and a longer lasting preservation if you do not pound it.

Instead, put the cabbage into a large bowl, and salt it in the bowl. Put about 1-2 tsp of salt for every half gallon or so of loose cabbage (not packed). Just grab a large double handful and put it in the bowl, and then sprinkle a teaspoon or two of salt over it, then repeat. Let the cabbage sit for about 8 hours. Stir it every hour or two, to help distribute the salt. You will see the liquid start to form in the bottom of the bowl.

NOTE: If life interferes, it is perfectly fine to pop the bowl in the fridge for up to 2 days, but it is best that it is stirred a time or two.

Pack the cabbage into jars – leave about 1/5 of the jar empty at the top for headspace. Pack it tightly. I use a wooden spoon to press it firmly into the corners and press it into the jar. Divide the juice between the jars.

Weight it down heavily. You want close to a pound of weight on a half gallon jar. Less on smaller jars. Enough weight to get the juice about to the top of the cabbage.

The key to this is the weight. Cabbage just takes a lot of weight at first.

Tip #3: More juice will form over the next 24 hours. Yes, the top of the cabbage will be out of the juice for part of that time. This is normal.

After about 24 hours, the juice should COVER the top of the cabbage. As long as it is covering it by at least 1/4″, it will be fine, because it will continue to settle and rise very slowly over the next few days. After about three days, you want the brine to cover the cabbage by about 1″.

Tip #4: If the brine has not covered the cabbage, or if you just cannot get it weighted down enough to begin with to reach the top, then it is PERFECTLY FINE to add additional brine. Mix 2 shy tsp of salt with 1 cup of cold water, and stir to dissolve it (keep stirring, it will work).

Tip #5: Let the kraut ferment at room temperature to start with. Some sources say to keep it in the dark, but I have never done so.

Fermenting times are variable, they depend on the temperature of your room. In the summer, when temperatures are higher, it will ferment faster. In the winter, it will ferment more slowly. It GENERALLY takes about 3-5 days to develop the initial kraut smell – a pleasant vinegary smell (if your house is cooler than 65 degrees, it can go more slowly). You can smell this on top of the airlock if you are using a compact silicone airlock.

Ideally, you leave the kraut to ferment at room temperature 1-2 weeks (counting from the day you PACK the jars). Yeah, there are people who disagree with this. Yeah, they say science is on their side, but they are not considering ALL of the science. If you want your ferment to not only be healthy, but also to be preserved well so that it will last in the fridge if life gets hectic, then ferment it 1-2 weeks at room temperature, because longer SIGNIFICANTLY reduces lifespan in the fridge otherwise.

Tip #6: Ferment it at room temperature for only 1 week in the heat of summer. Ferment it for 2 weeks in the dead of winter. In between, you’ll just have to ballpark it somewhere in between. You are dealing with temperatures generally between 65 and 80 (no AC). So base your guesses on where your home falls in that range. If your home is a steady 72 degrees year round, then ferment your kraut 12 days all year. Most of us can’t afford that though, and will have to adjust!

NOTE: These rules are different for various foods. The LARGER the food pieces, the longer they take to ferment all the way through. Smaller pieces take 1-2 weeks. Larger things like whole pickles take up to 3 or more weeks.

This is NOT EXACT SCIENCE!!! It never will be. Sometimes you may need to put the food in the fridge sooner due to circumstances in your life. Sometimes you may leave it a few days longer when something distracts you. THIS IS OK!! It won’t ruin it. It will continue the fermentation process much more slowly in the fridge. As long as it still looks and smells like FOOD, extra days out won’t kill it!

Tip #7: The only visual clue you have that a food is ready for the fridge is that the concentration of bubbles in the food will reduce some. This is not always detectible, it depends on how much the jars are handled, how tightly the food is packed, and how much brine – and with foods other than kraut, it also depends on the thickness of the liquid (thicker shows more bubbles than thinner). So you may or may not be able to tell by observation when that 1-2 week period is completed. Judging readiness for the fridge by temperature estimation is JUST FINE. Don’t fuss over this, just take your best guess. It will be RIGHT the majority of the time (trust your intuition… you have it for a reason!).

Tip #8: DON’T repack the jars as you eat the kraut. Not only is this a waste of resources from washing jars, it is counterproductive!

The theory is that you repack the jars to reduce air in the headspace of the jar. This theory was devised by people who make money from persuading you that you have to have an “airtight” container for fermenting (which is pure fallacy to begin with since we know the containers they sell are not airtight at all) and who really like the idea of selling you multiple sizes of expensive jars. So IGNORE THIS THEORY. It is COMPLETELY WRONG.

Repacking jars introduces many times more air into the ferment than leaving excess headspace does. The reason for this is that the BRINE protects the kraut from air exposure. This is borne out by years of tradition – the kraut barrel was packed in the fall, and emptied through the winter, and the top was generally only covered by a cloth. The weight was left on it, and dropped with the level of the kraut to keep the cabbage under the brine. That is all.

If you take all that cabbage out and dump it into another jar, you are not only unnecessarily exposing it to air during the transfer, you are trapping air bubbles in it, and oxygenating the brine as you pour it between containers. Removing some food and replacing the extender and weight is less disruptive, and keeps the food fresher longer.

Tip #9: You can reduce the number of weights as the cabbage ferments. Generally about the time you put it in the fridge you can remove some of the weights. You’ll know how many. When it floats too much, put one back. As you eat the food from the jar, you can also remove weights to use them elsewhere.

Tip #10: Fermenting is a CASUAL and ENJOYABLE business, not a fussy worrisome thing. It has been done throughout the ages in conditions that were not only less than ideal, they were often appalling! It has been done in makeshift containers with unwashed foods. It has been carried out in root cellars with dirt walls and mold or mushrooms in every corner. Mothers prepared kraut in the back yard, or in a kitchen with a dirt floor, or an unpainted and dusty plank or brick floor with kids running through in bare feet stirring up the dust.

Nobody had thermometers, or airlock jars, or refrigerators or temperature controlled houses. They did not even have precise instructions! They had vegetables, salt, water (of questionable purity), a large crock, makeshift weights (usually a plate), a ladle or spoon to skim off the foam. Yeah, there are other ways from other cultures as well, but this is American tradition. The pickle barrel and kraut crock in the corner of the basement or root cellar.

So the last lesson is, enjoy the art of Fermentation. Watch your kraut, smell it, taste it, and learn to see and feel the process.

The REAL tradition is not the precise directions. The real tradition and heritage that we can recapture is the art of noticing and getting to know the food and the process.

Enjoy your Kraut!

The ORIGINAL one-way valve fermenting airlock! Imitation IS the sincerest form of flattery, and we have noticed that our product has been copied by other sellers of fermenting products. Remember, if you see someone else selling a one-way valve airlock for fermenting, THEY copied US, not the other way around! Fermenta Lock is still the only original invention, handmade in the US. If it isn't orange, it isn't the original!

We invented Fermenta Lock, Fermenta Free, and the valve used for Fermenta Fido and other Fermenta Airlock products. We invented Fermenta Dunk Extender. Patents are prohibitively expensive, and designed by the government not to protect the rights of individuals, but to provide another source of revenue and control for the government and lawyers. We are good at what we do. We have endless ideas and endless creativity, and competition does not scare us. Impatient thieves do not scare us - they are too busy taking shortcuts to make a success of it anyway, and they won't want to take the effort to actually MAKE a product and fill orders.

So if you want to copy our idea, go right ahead. If you want to market and sell a competing product, you are welcome to do so, as long as you do not patent our idea - we had it first, and our posts on FaceBook announcing the invention and launch of it will prove that. This idea is officially in the public domain, placed there by us. We will NOT release supply sources, or part names unless you want to buy them - we'll be happy to sell you an instruction kit. If you buy our product, or look at the images and figure it out for yourself, good on you. Compete with us if you like, just don't screw us, and we'll get along just fine. Big companies who might want to screw us may have more money, and more lawyers than we do, but we have more to gain by suing the pants off a big company, and believe me, we will be well motivated to do so if anyone patents our idea and claims it as their own - this is a free idea. Everybody now owns it.

Published June 23, 2012

Wholesale, Export, and Manufacture of this product by other companies is an option. International distributorships are available for those wishing to export. Please email us to inquire about access to our wholesale website, or in regards to manufacturing any of our products.

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Uses of Fermenta Lock

Fermenta Lock is a compact airlock cap for mason jars, to help in making old fashioned brined pickles, and other lacto-fermented foods. Use Fermenta Lock for:

Pickles (all kinds)
Sauer Kraut
Milk Kefir
Bean Paste/Hummus
Sourdough Starter (if started with culture or yeast)
Anything which needs gas release without a lot of air circulation.

Customer Comments

“Living down in Guatemala, we have quite a lot of dampness in our houses and mold is an ongoing battle. After a long dose of antibiotics due to a parasite, I absolutely required probiotics to get my gut back in order and I know homemade sauerkraut has more probiotic content than anything else I could find here. I wasn’t able to make my beloved sauerkraut or even Kombucha in my kitchen because mold would start growing immediately on the top. Your Fermenta Locks have literally been a lifesaver for me! No more mold, and PERFECT Kraut EVERY time!!! Thank you for creating such a wonderful product!!!”

A. Kratzert

“Oh how I wish I had found you first!! Too many experts and too many bucks later I discovered your “Lock” and the sheer elegance and simplicity of your system.Thank you for your help and affordability, it makes healthy food attainable.”


“I came back to order more FermentaCaps. A wonderful innovation. I have not lost a single batch of sauerkraut since I started using the original Fermenta Locks.”


“Please continue your good work on producing such a great product. I’ve tried lots of other kinds of airlocks- the 3 piece water lock, pickle pipes, fermilid, boss pickler, and I think yours is the best design and quality. I’d like to order another 100 of them right now, but I’ll have to wait a bit. I’ve had lifelong health challenges. I’m 38 and about 20 years ago my health was so bad I didn’t feel like living most of the time. Now my health is the best it’s ever been and it wouldn’t be possible without fermented vegetables, they have made a huge improvement in my health.”


(Last names omitted to protect customer privacy.)