Why are jars often so hard to open?
August 4, 2017 3:50 PM   Subscribe

Why do food manufacturers regularly package food in jars with lids that are too large or too tight for a not-insignificant portion of the population to open?

I often struggle to open jars because the lids are either too tight or too large for me to fully get my hands around. I do have thin-ish arms and relatively small hands but I'm also a healthy, reasonably physically active woman in my 30s. I end up asking my husband who can almost always open the jars, but sometimes he will visibly be having difficulty himself (unless that's just for my benefit).

So my question...why exactly do manufacturers put their product into packaging that a good portion of the population can't open, or can't open without a lot of difficulty? Especially given that food preparation is more often and traditionally done by women.

I get that there is a certain level of jar tightness needed to ensure food safety, but is that the reason? Also tight jars I get, but not large jars that many people can't even get their hands around. Why do they do this?

Do the companies that make the jars actually do any testing to make sure people can get them open? Is this even a concern, given that people who regularly can't open jars just end up buying jar openers eventually? Is it because people are now more out-of-shape than they used to be and the jar/food companies just never got around to updating their designs? If not, why haven't they?

Help me, jar experts!
posted by eeek to Food & Drink (21 answers total) 1 user marked this as a favorite
Part of this is probably just that nobody tests them or particularly cares about whether they're openable because it doesn't make much of a difference to how many they sell so why spend the time and money on it? Few people buy their pickles based on the openability of the jar; cost and flavor are generally the overriding factors.

However there's also physics. Lots of foods—think pickles, jellies, anything with one of those tops that goes pop! when you open it—are put in the jars and sealed up while still hot. When cooled, the air inside the jar contracts and sucks the lid down tight. This is also how home canning works; it helps make a long-lasting, air-tight seal that will protect the product. It can also make the lids a pain in the ass to remove.
posted by Anticipation Of A New Lover's Arrival, The at 3:57 PM on August 4 [5 favorites]

The vacuum seal required to keep the food safe is what makes a jar initially difficult to open. My best technique is to use the dull side of a butter knife to whack the top edge of the jar a couple of times. That damages the seal and makes the jar much easier to open. Sometimes you can even hear the pffffft as you hit the lid.
posted by defreckled at 3:59 PM on August 4 [9 favorites]

If you hit the lid with a spoon and give it a little dent, it should pop right off. You can also use a can opener to pry the rim of the lid out a little in one spot to break the air pressure or suction that has built up and then it will be easy to open as well. But usually when I can't open a jar, the issue is my grip and my hands being wet or greasy from prepping other food ingredients. You can buy little grip pads to use and that helps too (and for some reason, I recall as a kid growing up getting a lot of jar grip pads from realtors as promotional material). I can't say I've ever experienced a jar too big for my hands, and I am a petite woman with little hands, but I am also not a chef or caterer.
posted by AppleTurnover at 3:59 PM on August 4 [1 favorite]

The reason jars are often difficult to open is because they've been essentially vacuum sealed, and there's much, much less air pressure inside the jar than outside. The hard part of opening the jar is breaking that vacuum. If they made the lids any looser, they wouldn't be airtight anymore, so bacteria could get in and contaminate the food (and the food could leak out.) Bigger jars with wider mouths are a function of physics for the quantity of food.

Bear in mind the cans and jars we use are basically Civil War-era technology. Nobody's done market testing on openability because that just wasn't a thing back then; the fact that people still buy jars after all this time means it's been working well enough, so why change it?

I have one of these and it helps me a LOT. Maybe you would benefit, too?
posted by Andrhia at 3:59 PM on August 4 [3 favorites]

I always manage to open difficult jars without fail, to the consternation of Mr MMDP and others. I will share my not-so-secret secret - tighten it slightly. It's entirely counterintuitive but it always works. It breaks the seal but doesn't take anywhere near the effort.
posted by Martha My Dear Prudence at 4:15 PM on August 4 [16 favorites]

Putting a rubber band around the jar lid will help give you grip and should make it easier to open.
posted by pseudostrabismus at 4:15 PM on August 4 [4 favorites]

Nthing that tightness is due to vacuum-sealing, which is for preserving the contents. (That's also why they always say to refrigerate everything after opening - you've broken the vacuum seal, so now you have to use cold to keep the bacteria at bay.)

As for how to cope - I've found that with especially stubborn jars, running the lid under hot water for about 30 seconds helps. Also, try putting a dishwashing glove on the hand holding the lid, that helps with the grip.
posted by EmpressCallipygos at 4:19 PM on August 4 [4 favorites]

The lids are the size they are because the jars are the size they are. They have to fit (often solid) food into the jar opening, so it can't be very much smaller than the jar is. It's also easier to get the food back out if the lid is bigger. The technology exists to make an opening smaller than the body of the jar (eg. in a bottle, or a carboy), but then you can't get all the pickles in--or out.
posted by Huffy Puffy at 4:23 PM on August 4 [1 favorite]

My go-to trick of opening jars is to hold the jar around the glass and hit the edge of the lid on a wooden bench or bread board. This jolt breaks the seal and they are then easy to open.
posted by Thella at 4:51 PM on August 4 [1 favorite]

I feel like *everything* is hard to open, whether it's jars or so-called perforated boxes or plastic cheese packages. Pretty much every day I think "I wish America's manufacturers could see me struggle to open their product! WHY." I'm a female person with small hands who isn't horribly fit but does work out. I use a grippy for jars and, secondarily, my husband, but I don't know what I'd do if I lived alone. The hot water and/or banging never really seems to have any effect when I do it.
posted by Occula at 5:06 PM on August 4 [7 favorites]

I used to do the knife/spoon trick, but I moved to the hot water trick. Something bugs me about damaging the lid. Running the lid under hot water expands the air underneath and releases the pressure that holds the lid tight.

My Mom used to can lots of fruit, and the lids would always be very tight when it was done. So this isn't an industry insight, but maybe it's related: The tightness of the lid seemed to be a result of the fact that the lid had to be closed when the contents were still very hot, for food safety. So by the time that it was down to room temperature, the air inside had shrunk a lot and put a lot of downward pressure on the lid.

To open those lids, we often used a jar opening tool that provided extra leverage. The modern version of my parents' metal-and-rubber tool looks to be something like this.
posted by clawsoon at 5:54 PM on August 4 [1 favorite]

I can't answer your question, but this is the tool you want. It breaks the seal so opening is easy.
posted by metasarah at 6:08 PM on August 4

Part of the problem is that many manufacturers make the threads on the jar too steep, which reduces the mechanical advantage of the screw (one of the so called 'simple machines', after all) as you try to turn the lid to open it, and they do that in order to make it easier to get the lid back on, because steeper screws allow for more places where you can 'start' the corresponding threads on the lid as well as an easier meshing when you do get the two sets of threads aligned.
posted by jamjam at 6:10 PM on August 4 [4 favorites]

I've tried every trick mentioned here, but the most reliable trick I've found is just putting on a pair of rubber dishwashing gloves. The improved grip makes it way easier to open anything.
posted by peppermind at 6:21 PM on August 4 [8 favorites]

I virtually never even try to open a can, bottle, or jar without my handy tools to break the seal. My favorite looks like a small cast iron bottle opener but is made for easily breaking the seal on almost any size jar or bottle. I also have a 5-in-1 opener that has the right tools for pop top cat food cans and soda bottles. Also handy is a little piece of plastic mesh that gives me a grip on anything slippery.

I won't mention my orange scorer or corncob scraper lest you think I'm obsessive.
posted by janey47 at 6:31 PM on August 4

In answer to the original question, I think most manufacturers don't think about the possibility of a jar that's easier to open. The thinking doesn't go beyond that's how jars are. If they want to go to an easier-to-open packager, they switch to a different kind of package altogether.

I believe food was packed in cans for 20 years before someone invented the can opener.
posted by SemiSalt at 7:30 PM on August 4

Sorry, the idea that massive international food packagers and distributors don't know or don't care about this problem is frankly ludicrous. Of course they know, of course they care. Give a company worth billions, with many thousands employees just in R&D a little bit of credit.

Overall, difficulty opening is a tradeoff between food safety (including shipping, shelf life, etc) and ease of use. For now, it's more cost effective to sell pickles that don't get moldy but are hard to open for some, compared to pickles that go bad more often but are easy to open for all. They probably can make a jar of pickles that is easy to open for all, and it lasts just as long, but the packaging (and QA/QC) make it cost 60% more right now, and since it is of limited appeal (to the small handed, the weak, the elderly, etc.), it's just not cost-effective in a mass market capitalistic system. It's every bit as simple as that.

However, "easy open" technologies are being continually researched, and lots of things are in fact much easier to open now than they were 30 years ago. For a quick example, here is a scientific research article precisely about how much force people twist with, and how easy it has to be to have 100% of adults age 20-30 to open it without struggle,and 97% of people aged 50-94 be able to open it. Just look at all the 16k hits on google scholar since 2013 for "easy open food jar". TL;DR: They know, they care, they are working on it.

In the mean time, stuff is hard to open for some people some times. It's not even just the vacuum seal. I'm sure most of us have had a very hard time opening a previously opened, not-vacuum-sealed jar of pickles or peanut butter or whatever.

The problem is screw resistance and friction. Think about how even weak people can lift a car with a simple screw jack, but how hard it is to turn a screw by pressing on it. It all depends on the thread pitch, and the coefficient of friction. Some lids are so smooth that if you drop it on top of the jar it will turn itself closed, but those are not very common, and only used for things like drugs targeted at the elderly.

While the tips and tools above are all nice and can help a little to break as seal or get a better grip (whack it with a butter knife, whack it on the counter, pry it various ways, use rubber band), none of them actually increase your delivered torque. And hence none of them help you with a jammed lit that is not vacuum sealed.

The absolute best, professional-grade, torque-multiplying gizmo for twist-to-open containers is this thing, and anyone who has every complained about a hard time opening jars should get a few.
posted by SaltySalticid at 8:36 PM on August 4 [14 favorites]

(apologies to clawsoon, their linked device does indeed give you mechanical advantage and multiply torque, I missed that at first read. It looks like a very good tool too :)
posted by SaltySalticid at 9:02 PM on August 4

People are also getting weaker hands than they used to have. As mobiles become more common, the hand strength a lot of us had from typing on keyboards is being lost. There was a time when most people did a lot of work that built muscular strength in the hands. When is the last time you stirred a batter with a recipe that instructed you to beat mixture 100 strokes with a wooden spoon, wrung out a sinkload full of wet clothes or did 20 minutes of steady hand sawing?

When I was a teenager whenever anyone in my family needed help getting a jar open we went to my middle sister, who played piano. She had the strongest hands. After she gave up piano they all started coming to me because I had taken up typing; I have been the family go to ever since. I also remember from my very early childhood, in the sixties when they sold jar openers as an aid to frail seniors and people with arthritis; it was assumed that they were the only people that would need help opening jars. In fact the home canning advice said that if you could not open a jar by hand you should throw it out because that meant that the contents had boiled up and gotten between the rubber ring and the lid and the glass and had glued it shut, and you therefore did not have a complete vacuum seal and bacteria could have entered.
posted by Jane the Brown at 5:45 AM on August 5 [2 favorites]

In addition to vacuum sealing, there's also the basic fact that sticky stuff is sticky. Nearly every watery-sugary jarred substance spills over onto the threads at one point or another, either in the canning process or after you open it and gloop the contents all down the side. That spillage dries and glues the lid shut. The trickiest jars IME are those that are both vacuum-sealed and gunked up, like pickles.
posted by Sys Rq at 10:14 AM on August 5 [1 favorite]

You know those paint can openers? They're what my family has always used to open jars. Just slip that edge under the lip of the jar and push downward a bit. It pulls the lid away from the edge of the jar and thus breaks the vacuum seal. Presto - easy open jar.

Some jars may require applying the opener in more than one spot, but it only takes a few seconds and after that the lid is still intact. The only thing that's broken is the vacuum holding the lid tightly onto the jar.
posted by Lunaloon at 10:22 AM on August 5

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