Rot your Food Right with Airlocks for Small-Batch Fermenting: Gather the Facts, Know Your Options {recipe below}

By Kirsten K. Shockey & Mara Rose

airlocks2What do a ceramicist, a classically trained chef and nutritionist, a former ad sales exec, and a reformed business analyst have in common? They are all working hard to make it easy for the rest of us to ferment our own food and drinks. Each of them has created a smart system to make it safe and stress-free to ferment small batches of food in Mason jars; these systems are called airlocks.

New to the home-fermenting scene and wondering what an airlock is? It’s a special system that allows carbon dioxide to escape from your container, while keeping oxygen out. Fermentation is a process that is ancient, very low tech, and forgiving. So, while an airlock isn’t necessary, using one takes some of the babysitting out of the fermentation process and allows you to “forget” about your little jar while the good bacteria process your veggies.

Using an airlock gives newbies the confidence to gain hands-on fermenting experience. Airlocks are not foolproof and, while it’s unlikely, you can still end up with scum (mold and yeast) in the jar. That said, scum is nothing to worry about—you won’t kill your family with scummy ferments. If you want a little help understanding what scum is and what ferments looks like when they’ve gone awry, visit the troubleshooting community on The Fermentista’s Kitchen.

In the meantime, read on to learn more about fermentation, the features of four different airlock systems (and the awesome people who designed them), and how to hop on the fermenting train at home.

How Does Fermentation HappenOR

In a word, bacteria. Friendly bacteria called lactic acid bacteria (LAB) live on fruits and vegetables, and when we create the perfect environment for them, they get to work making our food healthier (probiotics) and longer lasting (preservation). We could say a lot more about this but for now we want to focus on helping you create that perfect environment.

kimchi in trditional crock2All you need for lacto-fermentation is salt, a vessel, and some time. It’s a simple, ancient technique for processing and preserving food. For thousands of years, that vessel of choice was a clay pot, which has served us humans well with very little improvement or innovation. At some point along the way, a potter or a fermenter created a water seal crock, a ceramic crock with a moat in the rim that holds a bit of water, which acts as an exit-only doorway for the carbon dioxide—it can leave, but it cannot come in. This creates an anaerobic environment—an essential condition for fermentation.

Another more modern vessel of choice for fermentation is the Mason jar, which is appealing when a big crock feels daunting and unwieldy. A major bonus to using a glass jar is that you can see what is going on with your ferment. For example, it’s important to keep the ferment under the brine, and in a jar you can see if it’s staying down or if trapped carbon dioxide is pushing it up (which is called a “heave”—learn more about that here).

ckHatchLab_Kimchi-241webFermentation works in many environments: in open crocks, in crocks with moats, in Mason jars with lids, etc. Each container has pros and cons. If your vessel of choice doesn’t allow the air to escape on its own, you have to “burp” (cracking the seal momentarily to allow the CO2 to escape) your jar manually so it won’t explode. If you ferment in an open crock, the top layer of food will likely develop yeast and mold (though the layers below should be pristine) that you’ll need to scrape off. Large crocks with moats are a great option, but they’re expensive and big, and they aren’t always the right choice for those who want to ferment a little bit at a time or several different things at once.

Four Airlock Systems

In recent years, as home fermentation has become more popular in the US, a number of new airlock systems have hit the market. While this is great news, as a consumer it can be difficult to choose the one that meets your needs. To make things easier, we selected four airlock systems and Kirsten K. Shockey, fermentation expert and author of Fermented Vegetables, tested and reviewed each one.

airlocks4Three of the systems use water to create that one-way door we talked about earlier. For example, FARMcurious uses an adaptation of the traditional beer brewers airlock, while the Ferment’n cap uses essentially the same idea, just redesigned with a low profile that takes up less real estate on the counter. Kraut Source uses a trough system, not unlike the water seal crocks. Their stainless steel lid design is the whole enchilada: it contains a moat, a press, and a spring to hold the ferment below the brine. The fourth system, the Pickle Pipe, is a waterless “one way valve” or “expansion valve” that releases carbon dioxide only when the pressure has built up enough to push the valve open.

The comparison chart below is designed to help you pick which system (or systems) is right for you. Note that every system we reviewed can be used with wide mouth canning jars of any size.

Chart Final 12.10.15


We looked at one system outside of North America, SteriLOCK. While we haven’t included a full review, we wanted to give it an honorable mention because we like the lid. It is a low profile, simple one-way valve that plugs into a plastic Mason jar cap. It is the only system we know of for regular (rather than wide) mouth canning jars. Its most unique feature is a tiny carbon filter that can be added to keep the eau de ferment from wafting through the house. The downside is that the plastic Mason jar caps do not fully seal and can leak if tipped.

Meet the Makers

We love knowing the stories behind the things we use, and learning about the creative people who are working hard to help us live healthier, more creative, sustainable lives. Here goes:

FARMcurious Fermenting Set

  • Nicole Sunset Magazine Canning Class-smInventor: Nicole Easterday
  • Location: Oakland, CA
  • Funding: Raised $56,519 from 1,240 backers through Kickstarter
  • Inspiration: Nicole loves inspiring people who are terrified of fermentation to give it a try and she’s excited by the fact that, as she says, “Fermentation is on the leading edge of science.”
  • If she were a fermented food or drink, what would she be? “Water kefir. I’m bubbly and effervescent, sometimes sweet, sometimes dry, and entirely a product of what you feed me. I feel silly saying that, but since you asked…”

Nicole grew up in a German farming community in Kansas and her grandpa made sauerkraut. As a child, she mostly felt like it was gross and smelled terrible. It wasn’t until her move to San Francisco from New York City in 2007, where she encountered a whole new food culture, that she got interested in homesteading. Suddenly, she was surrounded by people who cared about things like local produce and farming methods. And she loved it! A little plum tree in her backyard proved to be her gateway drug. She learned how to make jam, which naturally led to pickles, and then to cheese, and then she got backyard chickens … and there was no turning back.

Finally, in 2009 Nicole launched FARMcurious (but kept her day job in ad sales and business development), a company that teaches traditional skills like cheese making, fermenting, canning, charcuterie, gardening, and mushroom cultivation to help people reconnect with the sources of their food. A couple of years later, as FARMcurious gained traction, she left her day job. She now manages a team of four enthusiastic food lovers.

Fermenting Set 9 (1)The first time Nicole tried her hand at kraut, she ended up throwing away 10-to-20 pounds of cabbage, which she hated doing. This experience led her to small-batch fermenting in Mason jars in the hopes of wasting less and increasing her success; from there the FARMcurious Fermenting Set emerged. She experimented with different parts of various sizes until she landed on a combination that did the job. In the fall of 2013 she started selling the pieces of the kit, and in the summer of 2014 the full set was born, thanks to a successful Kickstarter campaign. Everything in the set, including the packaging, is sourced from North America.

Nicole loves learning and sees that her customers do too. So, in positioning her company and their fermentation set, she’s focused on educating and supporting her customers, not just giving them a gadget and cutting them loose.


  • mikaelInventor: Mikael Kirkman
  • Location: Berkeley, CA
  • Funding: Self-funded
  • Inspiration: “I really do crave fermented foods. When I think about them, my mouth waters.”
  • If he were a fermented food or drink, what would he be? “I don’t know. I really like fermented onions. I think they taste really good, and they’re sweet. I just do red onions in salt brine. They ferment quickly; give them just five to seven days.”

Mikael, a professional ceramicist and maker of public art, is the creative force behind Ferment’n. He’s a self-taught artist who got his start in a tile shop right after high school. There he learned to make ceramic tiles and he hasn’t stopped making things with clay since.

Mikael’s grandmother is German and he grew up eating her kraut, but it wasn’t until five years ago that he started fermenting on his own. Inspired by friends who were doing it, he decided to give it a try. It wasn’t long before he was hooked, or before his fermenting friends started asking him to make them big ceramic crocks. While he was happy to oblige, the hefty price tag of $150-$200 for a custom ceramic crock proved prohibitive for many of his millennial friends.

As he contemplated ways to support budding fermenters and use his pottery skills, he landed on the idea for Ferment’n. He started by making weights in his studio, which were warmly received by his friends. Then, about two years ago, he began developing a prototype using wax for the cap that would fit on the mouth of the jar. He used his savings to have it manufactured, and today Ferment’n is sold online and wholesale to grocery stores and other interested businesses.

KitMikael makes the weights in his ceramics studio, and the BPA-free plastic cap is manufactured near Los Angeles. Mikael is committed to making “a product you want to use, that’s made locally, and that won’t make you sick.”


  • K_Diggs_BC (1)Inventor: Karen Diggs
  • Location: San Francisco, CA
  • Funding: Raised $184,133 from 3,355 backers through Kickstarter
  • Inspiration: Getting as many people fermenting as possible. She’s fascinated by the microbiome and how it impacts us all and she loves the history behind fermentation, the simplicity of the process, and the health benefits of the finished products.
  • If she were a fermented food or drink, what would she be? “Jun, because I love that it’s made from honey and it’s gentler than kombucha. It has a mysterious origin and doesn’t lend itself to mass production because it grows very slowly, but very well.” She likes to make hers with rose petals and hibiscus flowers.

Karen Diggs is a classically trained chef, nutritionist, food writer, and author of the forthcoming book, Happy Food. She studied at the California Culinary Academy (now Le Cordon Bleu San Francisco), worked in restaurants in Hong Kong for seven years, and then returned to the Bay Area ready for a shift from the crazy restaurant world. That’s when she found Bauman College, enrolled in a two-year program, and became a nutritionist.

Thanks to her time at Bauman, Karen got hooked on fermenting and became fascinated with traditional fermentation crocks. It was her fascination with the simple but elegant crock design, combined with her work as a nutritionist encouraging her clients to ferment more of their own food, that eventually led her to invent Kraut Source. One day in the shower, she realized she could shrink the large crock moat system and adapt it to fit on top of a wide mouth Mason jar. And that’s exactly what she has done.

IMG_2392A self-proclaimed plastic hater, Karen crafted her product out of high-quality stainless steel. It took longer than expected to find a reliable manufacturer with the same commitment to quality, but Karen eventually found one in China that she trusts. Her packaging, which includes a plantable paper insert pressed with dill seeds, comes from San Diego and her compostable boxes are made of recycled material.

Pickle Pipe

  • PhilBaronphoto.jpgInventor: Phil Baron, founder of Masontops
  • Location: Toronto, Canada
  • Funding: Raised $189,066 from 4,533 backers through Kickstarter
  • Inspiration: Fermentation is simple to do, it’s inexpensive, it’s delicious, and the products are healthy. He says, “We’re not changing people’s lives with the Pickle Pipe, but if it helps people make more things for themselves and eat healthier food, that’s great.”
  • If he were a fermented food or drink, what would he be? “That’s an odd question. I would definitely be kimchi. I’m a little bit spicy, pungent, and complicated, but delicious.” It also happens to be his favorite fermented food.

Phil feels a deep connection to Mason jars. His great-grandmother was a farmer who immigrated to Canada from Eastern Europe when there was no refrigeration and the only way to eat veggies in the winter was to preserve them. He tells of how his grandma would sneak into the kitchen at night as a child to eat sauerkraut by the fist-full. Even then, much of the preserving was done in Mason jars, and Phil still has some that belonged to his great-grandmother long ago. And so, after completing his MBA, and while working as a real estate analyst, Phil launched Masontops in 2013 to create a line of accessories for those handy glass jars.

At the same time, Phil began experimenting with fermentation to make use of the cabbage bounty from his CSA. His first kraut-making attempt in a large plastic bucket was a big failure. Shortly after, he learned about doing small-batch fermentation in Mason jars – an idea that appealed in part because, if you fail, you fail small. But it wasn’t long before Phil, a natural problem solver, began looking for ways to make the process easier. He developed Pickle Pebbles, high-quality glass fermentation weights that keep the veggies below the brine, first; next came the Pickle Packer, a wooden sauerkraut pounder; finally it was time for the airlock system, the Pickle Pipe.

_DSC9655Through an iterative process and with the help of an industrial engineer, Phil eventually landed on the right design for the Pickle Pipe. Now the Pickle Pipe is manufactured in China in a factory that also makes baby products. He’s quick to note that the factory has “been fully audited, and we send a third-party inspector to the factory to watch over production.” They also send samples of each product batch to SGS labs in North America to confirm they are BPA-free and Phthalate-free; Phil makes the report available on the Masontops website.


Inspired to give small-batch fermenting a try? Kirsten’s recipe for cebollas encurtidas (pickled onions) from her book, Fermented Vegetables, is below. This recipe has its origins in Ecuador and is traditionally a vinegar-pickled cebolla paiteña (a smaller and spicier onion than those widely available in the US). Enjoy your pickled onions and let us know how it goes.

Fermented Vegetables
Fermented Vegetables
Recipe: Cebollas Encurtidas (Pickled Onions)

Yield: about 1 quart


  • 3 red onions, sliced
  • 1 tablespoon lime zest (optional)
  • Juice of 3 limes
  • 1 teaspoon unrefined sea salt


  1. With a knife, trim away the ends of the onions by making shallow, cone-shaped cuts. Peel away the papery outer layers of skin and any damaged or discolored layers.
  2. Thinly slice the onions crosswise to make rings. Transfer onions to a large bowl and sprinkle in most of the salt, massaging the onions and salt with your hands. Taste and sprinkle in more salt as needed to achieve a salty flavor that is not overwhelming.
  3. Add the lime juice and the optional lime zest. At this point there should be brine building at the bottom of the bowl.
  4. Press your onions firmly into a jar or crock (no smaller than one quart). More brine will release at this stage, and you should see the brine rise above the onions.
  5. Top the jar with your favorite airlock system. If you don’t have one, top the ferment with a quart-sized ziplock bag. Press the plastic down onto the top of the ferment, fill it with water, and seal the bag; this will act as a follower and a weight.
  6. Set jar aside on a plate in a cool location, out of direct sunlight for 7-to-14 days. Check daily to make sure the onions are submerged, pressing down as needed to bring the brine to the surface.
  7. You can start to taste the ferment on day 7. Your ferment is ready when the onions are translucent, have lost their sharp bite, and taste pickle-y without the strong acidity of vinegar.
  8. Store your ferment in jars, leaving as little headroom (space between the ferment and the bottom of the lid) as possible and tamping the onions beneath the brine each time you remove a spoonful from the jar. Tighten the lid and store in the fridge for up to 18 months.

About the Authors

kirstenphoto2Kirsten K. Shockey is a mother and homesteader living in Southern Oregon who finds herself with increasingly fewer children at home, significantly less livestock in the fields, and way too much fruit in the orchard. Now she is also a writer and educator who is passionate about helping people take responsibility for their food. Kirsten and her husband wrote the book Fermented Vegetables: Creative Recipes for Fermenting 64 Vegetables & Herbs in Krauts, Kimchis, Brined Pickles, Chutneys, Relishes & Pastes. She maintains a blog to build community for enthusiasts of vegetable fermentation at

headshot2 maraMara Rose is the founder and CEO of Hatch Lab. An experienced educator and social entrepreneur, Mara lives in Boulder, Colorado with her husband and son. They all love seeing the mountains first thing every morning, caring for their worms, medicinal herbs, veggies, and fruit trees, and make medicine, cooking, and fermenting. They came to Boulder after almost ten years in Brooklyn, where they tended a little urban garden.

Editor: Maggie Wells
Photo: Christine Kiffney, Kirsten K. Shockey, Erin Kunkel (Used with permission of Storey Publishing), Karen Diggs, Philip Baron, and Andrea Willems 


4 thoughts on “Rot your Food Right with Airlocks for Small-Batch Fermenting: Gather the Facts, Know Your Options {recipe below}

  1. What is the small white airlock that you did not review? We have one designed like that we plan to larket sometime soon also. It is pretty much on the same style as that one. Also did you see the Pickle Pipe knockoffs hitting ebay???? Thank goodness we have a patent pending status on our product line.

    1. Hi Mike,

      Here’s a reply from Kirsten Shockey: “The small white cap is the Sterilock, it is company based in the UK ( I admit I am not keeping up on the many caps coming out, but I do know that many (like yourselves) have seen this niche and have come out with some very creative (and some less creative) options. Best of luck!”

  2. Thanks so much for the review. I have been using something like a cross between the FarmCurious and SteriLock from and will definitely try out some of these other airlocks for fun.

    1. Hi Tabitha,

      Thank you for checking out the airlock article. Please let us know which one you decide to try and how it works. What’s your favorite thing to ferment?

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