Today I was looking for some stats on stability testing or durability testing that may have been performed on Lock 'n' Lock containers, and I found the following.

According to their distributors, the manufacturer of Lock 'n' Lock containers is Hanacobi Co. Ltd., Korea. Hanacobi has introduced a new line of polycarbonate storage containers, which they call the Premium line.

Lock & Lock Premium is the upgraded version of the original Lock & Lock product, with an enhanced container base. Lock & Lock Regular is made of PP (polypropylene), while the Premium line is made of PC (polycarbonate). PC costs three times more than other materials . It is transparent, extremely sturdy, and can be sterilized at high heat, making it the most common choice for baby-nursing bottles.

Although Hanacobi probably has probably not published results of stability and durability tests, according to their US website, they claim to have conducted some tests for durability, gas permeation, and testing.

However, other manufacturers have published the results of their studies.

According to this study (PDF file), Corning compared stability and durability tests of their polystyrene storage containers against their polycarbonate storage containers.

Corning concludes that their Polycarbonate containers will endure a maximum working temperature of 138-143 degrees (C) and a minimum of -80 degrees (C). They have medium CO² Gas Permeability and High shatter resistance. Corning lists the PC containers as being able to be sterilized at high heat and pressure (autoclavable) - once - whereas the PP containers cannot.

Holy cow!! I don't like the sound of "costs three times as much" though.

~ Lou

They have medium CO2 Gas Permeability

which means they are NOT air-tight, if they are gas permeable at all.

if co2 can get in, then air can get out and moist air can get in. not good for logbooks.

nw

But if you look at the Corning report, they are talking about screw-top bottles as having medium co2 permeability, not LnL-type containers.

Polycarbonate is the same material that they make lightweight glasses lenses out of, I believe--the scratch and shatter-resistant type that you get for kids. Polycarbonate boxes ought to be plenty durable, but Oh that price!

Knit wit

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Lock & Lock Premium is the upgraded version of the original Lock & Lock product, with an enhanced container base. Lock & Lock Regular is made of PP (polypropylene), while the Premium line is made of PC (polycarbonate).

The key word there is base. I'm pretty sure the flaps on a Lock & Lock container wouldn't work if molded from polycarbonate -- the stuff is rigid and would snap rather than bend. Judging from the picture, I think they're making the base out of polycarbonate but the lid with the flaps is still polypropylene, just tinted a tan color.

Which would presumably mean that the base can be sterilized but the lid cannot. I suppose you can sterilize the lid via other means, such as spraying it with something.

The seal is in the base of a Lock & Lock, is it not? The seal may be neoprene on the regular Lock & Locks but could be silicone on these polycarbonate versions. You can buy silicone spatulas and the like, it's good for pretty high heat.

There are other types of food storage containers out there with latches that pivot rather than bend; the Click Clack line of containers come to mind, and the Snapware containers with the blue latches may also qualify. As long as the plastic doesn't have to bend, you can make the whole thing out of polycarbonate -- and now that I think about it, I'll bet that's exactly what the Click Clack containers are about. The few I've seen all looked like they were polycarbonate, I just didn't think about the importance of that at the time.

BTW, I don't believe polycarbonate holds up to sunlight very well. Somebody might want to look into that to be sure before we start planting such containers. Of course, most plastics don't hold up to sunlight well, so either hide them somewhere dark or otherwise protect them from sunlight.

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They have medium CO2 Gas Permeability

which means they are NOT air-tight, if they are gas permeable at all.

if co2 can get in, then air can get out and moist air can get in. not good for logbooks.

I suspect you're misinterpreting the message. Everything has some level of gas permeability, including your car tires, which is why they will gradually lose pressure if neglected. The very fact that these guys even conducted tests of gas permeability probably means these things are so airtight that people who want stuff sealed well enough for laboratory use might want to use them. Gas permeability tests on most food storage containers would be a joke, you can't even get the lid to quit leaking long enough to conduct the test.

I don't believe polycarbonate holds up to sunlight very well.

Polycarbonate is what they make airplane windshields out of and so it must hold up to sunlight. ?? At least, I would think. The manufacturer also did those infamous "crash tests" firing frozen chickens out of some high powered "gun" at the windshields trying to simulate birds?! and other things that might hit a windshield! lol The PC held up perfectly! (So no worries about EVER having the windshield of your plane shattering because of those pesky frozen chickens flying the friendly skies!!) =P

A company I used to work for made the first negotiations in the US with the L-n-L company and I got a lot of the training when our company still had exclusive rights to this product. The seal is in the lid and there really isn't any other product out there that comes close to L-n-Ls in my opinion.

The seal is in the base of a Lock & Lock, is it not?

do you mean that you are assuming the silicon seal is in the base of the container?
the seal is in the lid of all LnL containers I have ever seen

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BTW, I don't believe polycarbonate holds up to sunlight very well.

I've got polycarbonate glasses lenses and have had the same lenses for three years. I haven't noticed any degradation yet. :-)

Knit wit

Looks like the tests while scientific don't address what we want to know: How long can we expect these to remain water-tight?

I was involved with Hot Air Ballooning and one manufacturer was supposed to conduct a test of a new blast valve (it is what releases propane to heat the air), then take the thing apart to measure wear. Well in their mind the test was going great, so lets run it till falure at however many cycles it was. They had to re-do it because it didn't answer the question of how much wear at 10,000 cycles as a base line for when to replace the valve. Which they thought was government BS, but still, was the point of gathering the data. How much wear at 10,000 cycles. Not when will the thing bust. Don't want to find out the max number of cycles was unique when the thing fails at 1,000 ft. Want to know if there is an acceptable amount of wear at 10,000 cycles to run it to that point. In not, then find out why not, or the hours have to be backed down.

So how long till the seal breaks down? Then I can back off an appropiate period (15%??) and know when to replace the box.

Ok, I emailed johnny@locknlock.com

Greetings, I am involved in a hobby called "Letterboxing" (http://www.letterboxing.org) where we hide a stamp, usually hand carved (much like most Japanese tourist spots have a stamp for a journal as a souvenir), and a log for personal stamping then provide clues for the "treasure hunt". Affordable, durable boxes are always sought after as many logs are lost when moisture enters the box and even several layers of zip-lock baggies when those seals fail.

The Lock & Lock containers are being discussed by many as a great new container for Letterboxing. My question is how long under climate conditions that range across the testing spectrum reported (-20 ~ 130) can the seal be expected to last? I am asking about time vs. hinge cycles so a person could make a prudent guess on when to replace the container.

Thanks,

Ron

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So how long till the seal breaks down? Then I can back off an appropiate period (15%??) and know when to replace the box.

Wow, that's going to be tough. My guess is that the seal itself is silicone, which means I suspect it'll last nearly forever; the biggest problem will probably be if it comes loose and falls out or otherwise gets physically damaged. That won't be so much a function of time as abuse or mistreatment; you could destroy the seal with the first visit if you try.

The container itself is another story. That milky-colored plastic tends to harden with age and possibly exposure to sunlight or weather. Takes a long time just sitting there, but perhaps just a little hardening would severely shorten the lifespan of those flexible hinges. They're great when the box is new, but what about after it's been sitting in the woods for a couple of years? Will the plastic eventually deteriorate to the point where a find flips the latches and they simply fall off?

I'm betting the answer is yes -- but the time involved must be quite a while, because I haven't found any L&L's that were anywhere near this deteriorated, and some of them must have been out there a couple of years anyway.

L&L's remain the best option we know of so far, AFAIK. There are types of jars made of either acrylic, ceramic, or stainless steel that have a rubber gasket and a metal flip-top latch that might work very well, but unfortunately I have yet to find one in which the metal flip-top latch was stainless steel -- it's crummy plated steel, even on the stainless steel containers. Hence, it will eventually rust away and fall apart -- perhaps just as quickly as the L&L's plastic degrades.

I use screw-top jars with shower pan liner gaskets inside, but I know they won't last forever either. I've found similar containers in the woods -- litter -- where the cap has cracked due to the plastic drying out and hardening with age.

I dunno if paint helps their durability. I paint nearly all of my containers these days. If the issue is exposure to sunlight, perhaps the painting will help them last longer. But plastics just tend to offgas plasticizers over time anyway, sooner or later they'll get hard and crack.

There are several kinds of containers out there that have locking compartments that are made of plastic and such...that don't look like sandwich containers...they look like things you see every day and don't think twice about. Stroll though a hardware store and look around. While not all of these things would look natural in the woods, many blend in nicely with the urban environment. Just a different way to look at it if you're more into the urban game.

"X"