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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.

A jar does NOT need to be airtight to create an anerobic environment!

Proper fermenting requires that only one criteria be met:

Brined foods need to stay under the brine.


More solid foods need to stay in an environment where gasses get out faster than they get in.

In fact, proper fermenting necessarily PROHIBITS an airtight environment. If it were airtight, gasses could not escape.

Air can get IN, just as easily as it can get OUT of a water-lock airlock system.

It DOESN’T do so very much, because of AIR PRESSURE.

As long as the air pressure INSIDE the jar is greater than the pressure OUTSIDE the jar, gasses will move one way.

Air is not like a mischievious child. It does not try to sneak in anywhere there is an opening. It is well-behaved. It follows rules.

If air pressure is equal, it will slowly drift back and forth in a lackadaisical exchange, IF there is an opening large enough to allow it.

If air pressure is greater on one side than the other, air is PUSHED, from the HIGH pressure area, to the LOW pressure area. Bigger gaps allow this to happen at a faster rate – if there is even a plastic to glass, metal to glass, rubber to glass, or even glass to glass (where the fit is smooth) contact, air will not move without a difference of pressure. The tighter the fit, the greater the pressure required.

An airlock works by putting a minimal barrier in the way, so the pressure has to be greater before large amounts of gas move. When pressure reaches a certain level, air can be forced through. In general, with fermenting, OUTSIDE air pressure will never be greater than INSIDE air pressure, so when gaps exist, gasses will move ONLY in a single direction… except for the transfer of some air through the water, which is a second issue.

This means that in most instances, a jar with a loosely capped lid will work just as well as an airlock in keeping gasses from building up inside, while keeping outside air out, if you can get it at just the right tension.

Open Fermenting, when done correctly, also works just as well as closed fermenting, because the food stays under the brine, where insufficient air is able to circulate to promote the growth of bad microbes. Oxygen has more difficulty moving through salt water than it does thorugh fresh water, so the salt brine on the foods helps stop the air from getting to the foods in the brine, which is one of the reasons that the growth of unhealthy microbes is inhibited. Yes, a slightly DIFFERENT complement of microbes will grow in an open ferment. But they are not unhealthy. Salt brines also limit the growth of unhealthy microbes in other ways – many bad microbes simply cannot live in a saline environment.

Even closed fermenting REQUIRES that the foods stay under the brine in order for them to properly ferment. If various manufacturer claims about fermenting requiring an airtight environment were true, then it would not matter whether the food was under the brine or not – the microbes could not survive either IN OR OUT of the brine, so there would be no need to sell such things as Dunkers and to give elaborate instructions on keeping food under the brine, nor to insist repeatedly that it do so. The system, being a system, simply provides people with a step by step which they feel obligated to adhere to.

Fermented foods will store better in a tightly capped jar – after the need for gas release is past, a tightly capped jar in the fridge will store them perfectly well. Again, it is not necessary that the lid be “airtight”, for the same reasons it is not necessary to have an airtight lid during fermentation, even if you want “anaerobic conditions”.

Remember, air moves according to PRESSURE. As long as the seal is sufficiently tight to prevent air movement under EQUAL internal and external pressures, you’re good. Canning lids, by their nature, tighten into a seal when external pressure is higher than internal pressure. So outside air won’t really get in.

If inside pressure is greater, the gas build-up will just slowly vent. No problem, because then the inside of the jar is filled with gas, not air, and that is what you want anyway. Fermented foods that have not been killed by canning will continue to slowly ferment and release minor amounts of gas, even in the fridge. That is ok, and a good and healthy thing.

Airlocks are a rather new invention in the history of fermentation – only used within the last few hundred years, primarily for brewing, and even then, not exclusively. Most alcohol was open vat fermented, or fermented in casks with an open hole to let out gas and scum buildup. People have been fermenting foods for many thousands of years, and only using airlocks for at most, a few hundred. So just what is the traditional method here? Whose tradition, and how far back?

So why do canned foods spoil if they fail to seal? There can be several reasons, most not applicable to brined and fermented foods.

  • The temperature may have been insufficient to kill harmful microbes in the jar, so they continue to grow.
  • All of the air may not be released from the jar during the process.
  • A piece of food, or a crack in the rim, may allow larger amounts of airflow that are not hindered by the rubber seal. Air may be sucked in, especially during the cooling down period, when air pressure inside the jar is rapidly declining (this is what usually pulls the lid down to seal it – but if there is a gap around the edge, air will be sucked in instead).
  • They are typically NOT salt brined. Salt inhibits the growth of many types of harmful microbes.
  • They have not gone through an alcohol phase – alcohol also inhibits the growth of many harmful microbes. Fermenting of many foods produces alcohol which in turn helps to preserve the food. If allowed additional air circulation at key points, it will typically move through the alcohol phase and into a vinegar or acid phase. This is particularly true of sugary foods. More sugar produces more alcohol. Both alcohol and acid help to reduce the growth of harmful microbes.
  • Since those foods haven’t been properly fermented, they are left defenseless against opportunistic invasion by harmful microbes, which quickly overwhelm the food.

To maintain an airlock environment while fermenting (which may make it easier to get a good ferment in some environments), the environment does NOT need to be airtight. It merely needs to allow air OUT, but to discourage it from coming IN. The fermentation process itself will create the proper environment inside the jar if you provide a means for gas to escape that does not allow large amounts of air back in. Air pressure will keep the gasses moving in one direction only.

Remember, water locks are NOT airtight either. Air CAN move through the water – and it will do so regardless of whether you see bubbles or not, because it will move through the water anyway, at a molecular level. A certain amount will circulate back into the jar, independent of air pressure, because air DOES move through water independent of pressure – it is more dependent upon temperature differences. This means a water lock CANNOT produce an airtight environment, and provides additional proof that an airtight environment is in fact not necessary to any kind of fermentation, except high alcohol content beverages. (The website of a major airlock pickling system states only that the airlock “reduces” oxygen, not that it eliminates it, and makes NO claim that their airlock is airtight, only that their seals are airtight – which sort of defeats the whole “airtight” concept anyway.)

A one way valve which allows air out, but which closes tighter with increased outside air pressure does not let air circulate through any medium (this is what we created for Fermenta Lock). It simply lets the gas out, and inhibits entry of air from the outside unless outside air pressure is VERY great. It does not need to be airtight, because it is designed to move air only in one direction, unlike a water lock which lets air move either direction through the water (again, it is relying on air pressure INSIDE being greater than OUTSIDE to prevent large amounts of air movement, but due to using water, does not prevent air from entering the jar and cannot in any way be classed as “airtight”).

It is also important to point out that some types of foods MUST have broader air circulation than a lidded jar will provide. They need a cloth or something else that allows two-way air circulation, in order to ferment properly. Vinegar is one such item, wild yeast is another (when making sourdough starter without using anything but airborne and naturally occuring yeasts present in the flour to begin with). Air circulation is important for these items. This is why a cloth over the top is the traditional way of doing these fermentations. Airlock systems are inappropriate for these items.

If you choose to use an airlock system, it helps to understand the principles under which it operates, so you know when to use it, and when a regular lid will be sufficient, and when a cloth or cotton cap over the top is a better option. And please don’t feel superior because you are using an “airtight” system, because you aren’t.

If you choose to open ferment brined foods, it is also important to understand the basics of good fermentation – keep the food under the brine, observe it from the OUTSIDE as much as possible, and keep out of it unless you are using it – don’t fuss with it during the initial fermentation period when you are not actually using it. When fermentation is completed to your satisfaction, pack it into clean jars (or leave it in the fermenting container), with brine to cover, put on a tight lid, and pop it into a cool location for storage.

There is NO “One Right Way” to ferment foods. Many ways work, and they can be affected by location, individual circumstances, available food supplies, and other factors. There are MANY right ways to do it. Pick the one that works for you.

Good fermenting tools can help you to ferment foods more easily and to streamline a predictable routine more quickly, but if you are having to make-do with something less perfect than you wanted to be using, take heart! Our ancestors had to do the same thing, and they did so successfully for millennia. Get what you can, piece by piece, and simplify one task at a time if you need to.

We recommend:

Get Fermenta Dunk, and Dunk Extender first (easy to do, since the Dunkers come with a free Extender). Because keeping the food under the brine is most important.

After that, get what you feel will help you most for the things you ferment – Fermenta Crock, Fermenta Cap, or Fermenta Lock. The choices are yours for how YOU ferment foods.

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.

Business Building Services Are Available - If you are wanting to build a business like this, where you make things in the home and sell them direct to the customer, or if you want to build a business that you can sell to other people as a complete business package, Firelight Heritage Farm is now offering Cottage Industry Services to aid small business owners in building a successful product or service business from the home. Don't know what you want to do? We can help you figure that out too (something original, and just yours, not a canned business). You get the wisdom and uniquely successful perspective and experience of people who have been business, marketing, and website professionals for more than a dozen years. For more information, visit Why copy someone else's business when you can do something uniquely you and enjoy it so much more?

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This website is only equipped to handle orders from US customers (International shipping must be calculated for each order). International Orders are now accepted BY EMAIL from UK, AU, CA, and shipped USPS (other countries will be considered if requested). Please email a list of the items you wish to order, using our Contact page, and we will give you a shipping quote, and then invoice you from PayPal for the total.
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.)