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We’ve talked about a few different vessels you can use for fermentation and one of the favorite jars of many is a plain and simple Fido jar. It’s a wire bale jar imported from Italy. I love these jars to the point where I may have a slight obsession with them
Is it safe? Honestly, if you want to do it, I’m not stopping you. Here is the deal though, fermentation is not what these jars are intended for. It’s been said that the jar’s wire bales are made flexible enough to allow gasses to escape as part of the canning process, implying the same should be true for fermentation but that’s just not true. They are intended for canning and storage purposes and that’s it. Fermentation creates much more gasses (read pressure) than canning.
I emailed Bormioli about it a while ago but received no response. I do believe they aren’t saying anything period on the topic. But I did get an interesting comment on the blog last week from someone “in the know”. My blog post where I question the safety of fermenting in Fido‘s received this comment:
I am a fido wholesale direct importer and dealer…. For over 30 years… The usage described is NOT a recommended usage without venting. The jar is NOT made for self venting by stretching the lid with pressure.
This warning was removed by another blogger on her site. … She thinks I am in “collusion” with a company that uses the vent system…. Instead of realizing I am just warning people that they are using it in a way not intended. Yes, many have success but is it worth the off chance of injury?
Yes… Build up enough pressure and a jar can explode…. That is a fact.
–Robert Lieberman, www.glaspak.com
So of course this peaks my interest and I email Robert for more information.
Here’s the deal: Most jars should be able to hold up to the pressure of fermentation. Most but not all. Fido jars are annealed which means once they leave the mold, they are put right into an annealing oven, heated back up to 2,000 and then the temp is slowly lowered. This process makes the glass stronger than glass that hasn’t been annealed. Other glasses (from Asia, Eastern Europe and Mexico) are cooled in less than a minute so they use a thicker glass to make up for it.
Even thought Fidos are annealed, there is still a chance of thermoshock fractures. A very small chance but it’s there. The jars are inspected by human eye with a fluoroscope at 20 jars every 2 seconds and jars with visible thermoshock cracks are discarded. But some get through.
This is not meant to scare you, this is just meant as a warning. If you are fermenting in Fidos (I admit, I do it when I run out of lids with airlocks), be careful. Like I said in my other post, vent the jars daily. If you own as many Fidos as I do, you’ll know some jars balings are tighter than others. You might want to vent the tight ones daily or don’t use them during the active fermentation stage. It’s simple to do, just lift the lever until you hear the gasses escaping and then seal it up. The gasses will build up again so if any oxygen did somehow get in while you are venting, it’ll be pushed to the top. I’ve not had any visible problems with mold or oxidation using this method.
I do still prefer to use an airlock so I don’t forget to vent. Plus, I’m still unsure about the effect built up CO2 has on a ferment. Keeping a Fido closed will build up enough CO2 to push it back into the ferment making your pickles fizzy, not just the liquid. Kinda cool but I’m not sure how it affects the health of the ferment.
And as far as Mr. Lieberman being in “collusion” with their customers? That’s just silly. GlasPak sells Fidos with or without the hole. Heck, they probably make more money from selling Fidos intact than to companies that drill holes in the lids.
ETA: While this information pertains specifically to Fido jars, the same holds true even more so for other wire bale type jars. Fido jars are high quality where most other wire bale jars are not as awesome. I will not ferment in a jar that is not a Fido jar even with venting.