What is the shelf life of common adhesives?

I'd bet the manufacturers web sites would have information on shelf life. Double what they claim, and you'll have a more realistic number.

Refrigeration extends the working life of most adhesives.

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** Double ??

** A local supermarket store was offering a nice discount on 100gm tubes of famous brand silicone adhesive, the "neutral cure" type that is useful in electronics.

I bought two tubes and soon found they had been filled with "acid cure " material - no use at all as the acetic acid vapour corrodes any copper it gets near.

The warehouse asked me to send them the bad tubes for appraisal and shortly afterwards a parcel arrived with 12 tubes of the correct "neutral cure" type.

Unfortunately, most of the 12 tubes had gone rock hard they were so old.

.... Phil

Double of what claim? I can't seem to find shelf life, or how long it lasts after it's opened, for most adhesives. Have you actually experienced double an unstated shelf life?

As Phil mentioned, that doesn't work. I've tried the same thing with RTV (silicone seal) caulk tubes. It's about the same with or without refrigeration. It lasts about a year no matter what I tried. For example: "When stored in the original unopened containers

Silicone Adhesive/Sealant has a shelf life of 12 months from date of shipment." That means if it's been sitting around collecting dust at the hardware store for 6 months, you might have 6 months of useful life. If you've used the tube, it's likely to be less than 6 months.

I appreciate your comments, but it would be more helpful if you provided your experience with adhesive shelf life and lifetimes rather than guessing what it might be under contrived circumstances.

Update: The JB Weld KwikWeld didn't hold. Instead of drying hard as the proverbial rock, it dried into something more like hard rubber. Apply a bit of force to the hinges and it fell apart. I also bought some Devcon 2 ton epoxy. However, when I tried to squeeze out the resin, I found it to be crystallized in the tube. I mixed it anyway to see what would happen. The result was something that looked like hard styrofoam, full of air/gas bubbles. Useless.

I just found a "new" tube of Ace Hardware 24 hr epoxy that looks good. Hopefully, it will hold together. This is getting ridiculous.

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Jeff Liebermann     jeffl@cruzio.com 
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Just about all epoxies have a shelf life of one to three years. Same if opened.

Gorilla epoxy seems to last the same.

Cyanoacrylates if opened last only up to a year at most, otherwise a year or two in the sealed tube. Gels don't last as long as the liquids.

White/wood (Carpenters grade is what we use) glue lasts a long time as long as it is sealed, we have a bottle that is at least five years old and it works just fine.

Rubber cement hardens in the can after about five years if sealed, one year if ever opened.

RTV seems to last a few years if sealed and only a few months if the tube is ever opened.

Gluing metal to metal is difficult at the best of times. Any chance you can use silver solder? I yet to find a suitable consumer grade glue that secures metal to metal reliably.

John :-#(#

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Store superglue in sealed jamjars with a transparent sachet of activated silica gel or if in a sachet thensome loose crystals in the jar also ,no trouble after 5 years. Use gel with a colour indicator for dry/damp, not too obvious with plain white/off-white colour of damp/dry silica crystals

I never found acid cure do much of anything to copper. I put some on circuit board to test. Contrary to reading, i believe the stuff passes moisture and corrode metal underneath.

Greg

I often use GOOP as it's tuff, sticks well, slightly flexible. Also similar E6000. takes some days to fully dry. Stuff evaporates from tube if put on wrong.

Greg

I've got epoxy in plastic tubes bought somewhere around 15 years ago, it's still fine.

The rest probably is nothing new... Cyanoacrylate never keeps well, but I've not tried anything special with it. Glues generally last best afer opening if capped off with ali foil, for containers that have no lid. Plastic film just doesn't do it. White pva lasts over a decade no problem, but some can moulder in the gallon container. Bitumen glue lasts well if the solvent doesn't disappear, it can always be redissolved with paraffin/kerosene. Never use diesel.

NT

Jeff, you ARE the authority on most everything, so I probably should bow to your expertise. (But I won't) After all, you have been in the repair biz t oo long.

Re-read Phils post -- he did not mention refrigeration "not working". He sa id the replacement tubes were "so old".

Double unstated? What does that even mean? Obviously if it's unstated, even 1 day is potentially double that.

YES I've had success refrigerating adhesives and silicones. Cold always slo ws chemical reactions, it's basic chemistry. I've had sealed tubes of caulk last 5 years in my garage fridge. Please be cautious about accusing me of "contriving" anything.

I also refrigerate batteries, and I've got some Panasonic industrial C cell s that are still at full cell voltage after more than 10 years.

So you did find something regarding shelf life? Or not? Which is it?

Unopened tubes of adhesive, if well manufactured and packaged, seem to last a long time. I've had silicones and cyanoacrylates last for many years. I have limited experience with epoxies, but one tube of plastic-specific epox y has lasted at least two years -- even after being opened.

I almost always seem to be able to find a manufacture date on the tube, eit her printed or on a crimp. Not so much on the tiny drugstore "superglue" pa ckages. Reputable manufacturers commonly publish a short number for shelf l ife, (sometimes you have to actually ask for it) as you saw, 12 months, but in reality, that is a CYA number so that the consumer will 1) not be disap pointed when his 2 year past date product goes bad, and 2) feel the need to buy another tube and when the stuff only *might* be bad. Helps revenue.

I've found 3+ year old product on the shelves in the orange big box home st ores. Caveat Emptor. Their warehouses do not have a FIFO system, and are no t climate controlled.

lls that are still at full cell voltage after more than 10 years.

I've still got some unrefrigerated ZnC & alkaline cells almost twice that a ge, so yours should last a long time yet. What I notice is that while most keep, a minority go from full to zero at some point. It's as if some sort o f fault occurs internally and they then drain out.

NT

REF:

I have ten year old unopened Toyota FIPG (aka RTV) that I "hope" to use for a valve cover gasket. I "hope" it's still good.

I do know that the tube of Home Depot gray-putty-like two-part "tootsie-roll" epoxy (with the cream in the middle) does NOT last more than about 5 years (ask me how I know).

The epoxy still works, but once opened, and half used, the rest dries out easily (I didn't re-wrap it though).

Likewise with "opened" cyanoacrylate ... I buy the *smallest* tubes I can find, because, to me, they're single-use only. They may last a few weeks once opened, maybe even a few months ... but not more than that.

The bigger bottles get runny ... like water ... and never stick, in my experience.

Greetings Jeff, I don't know about the shelf life but I do know about bonding metals with epoxies. Aluminum can be especially hard to get a good bond on because of the oxide coat. But this problem is fairly easily overcome. Apply the epoxy to a clean oil and grease free surface. Then use a small stainless wire brush to scrub the epoxy covered surface. Using this method keeps oxygen away from the aluminum during the scrubbing and the scrubbing action removes the super thin oxide coat. The particles of aluminum oxide just get mixed into the epoxy. The epoxy will wet the now oxide free aluminum surface. This process also works when trying to solder aluminum. I have had to prove to a couple people while they watched that this method works. Eric

Nothing specific Jeff, but a couple of observations of various glues..

Cyanoacrylates: I've bought stuff brand new that was crap. There are no da tes that I can discern (well, with my eyes anyway) on the package so it's a crap shoot. If you buy from a high turnover store, it should be fresh. Th e way I test it is to put a *tiny* drop of glue on the tip of my index fing er and immediately push my thumb into it and hold for a full second. If it comes apart, the glue is crap. If it sticks tight, it's still good.

RTV: Permatex makes all sorts of RTVs, but unless you use the entire tube i mmediately, it's gonna be junk soon. The reason is that the plastic caps t hat Permatex uses split. If you put the cap on too loose, air gets under t he cap and you get a rubber plug in the neck. Too snug and it splits and y ou have a ruined tube.

I bought some RTV at Harbor Freight for half of what Permatex sells for any where else, it's made in the U.S., works just like the Permatex stuff and t he caps don't split. Cheap and I can reuse it. Double win for me.

Circa 5 years, and it's generally water-catalyzed, so a paint can sealed tightly, with some CaSO4 dessicant, can keep it fresh for an extra year or two, even if the cap is gone. I did this for a tube that split open, it stayed fresh for months.

Those are best kept in a refrigerator. I've got a little wood-block with blind holes in the top as a stand, so the tiny tubes can sit upright (and to hold a leak). Unopened, I dunno how long.

Very sensitive to cold, do NOT let it freeze. Otherwise, I'm pretty sure a useful bond can be made from 20-year-old (but it may need water added). It's inexpensive, for a big project just buy fresh glue.

...

I had some EverReady and Duracell AA batteries from 1980 that still seemed fully charged in 2006 (voltage reading of 3.67 over 3 cells in series) - found when I unpacked a group of new old stock pinball and video arcade games that used them for the battery backup. Some batteries had leakage, but not many. I should still have those batteries around here somewhere...so 26 years (1980 to 2006) wasn't bad, if I find them I'll see if they still hold up after 38 years.

Photo of testing the batteries in 2006:

ftp://flippers.com//usr/www/users/flip/images/Will-Robotron-Cocktail-NIB-563871-BatteriesGOOD72DPI.JPG

These batteries were not refrigerated by the way - sitting in a (50F to

80F depending on time of year) warehouse in downtown Vancouver, BC for most of their life.

John :-#)#

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In my experience the rubbery, not really hardened epoxy has been due to inadequate mixing. I've found that you need to really mix the epoxy well. For even a small amount I mix for at least 30 seconds, sometimes more. As for age, as long as the resin hasn't solidified/crystallized, it still works.

I have used a two part epoxy since the middle 80s and I have kept it

10 years without degradation. The only down fall, but no way a deal breaker, is it comes as two 4.5 oz toothpaste type tubes, after 10 years it's bound to sprout a leak. I'm just careful how I squeeze and roll it up. I brought a partially used package with me when I moved from Michigan to Fl. in 1994, I used that and have bought two packages since then. All that said, the manufacturer says 12 month shelf life. ( maybe for NASA) The package I have now was manufactured 1-30-15 and still works as new. I keep it in my climate controlled home A little goes a long way, most of my repairs are 3/8" lines and then that is to much, but easier to get equal amounts when squeezing and eyeballing equal amounts. I see 10 minute set advertised, I find it is quicker. Maybe I'm just having so much fun time goes fast. :-)

It was originally called Araldite by Ciba-Geigy. Now it is owned by Huntsman and is called Fastweld 10. Here's a good explanation.

Here's a seller. Not sure it is the best price.

Here a couple dollars cheaper.

I doubt your mileage will vary. :-)

Mikek

Datasheet,

Let's cut to the chase:

a) Shelf-Life is not uniform. Factors such as heat, humidity, temperature c ycling, even altitude and more must be included in the process. b) The nature of the adhesives are factor. c) That some components will separate into separate ingredients depending o n temperature is a factor. d) That some cures are catalytic is a factor - and that once started, will continue until complete. e) That some cures require exterior stimulus is a factor. f) And some low-end epoxies will crystallize, one part especially, even whe n fresh with a single exposure to low temperatures.

During the summer, my hobby room will undergo pretty wild temperature swing s. It has windows on three walls, the center of which faces south. That is a factor.

I use some slightly exotic cyanoacrylates. They do not like temp.cycling an d last about a week when after opening - and I do refrigerate them for that reason. They will last about 90 days (refrigerated) if not opened, and are dated as such. These I purchase when I am about to begin a project, not be fore.

It depends on many things:

Storage Use factors Specific needs

If I am fixing something as basic as a Bakelite knob for a radio, pretty mu ch any run-of-the-mill super-glue will do the trick. If I am setting the ba llast-release on a $3,500 submarine, not so much.

What is on the label, you can be pretty assured, is what the manufacturer i s willing to support against unknown users with unknown habits and unknown storage conditions. Nor will they guarantee the workpiece against failure, just the cost of a tube of glue.

Let yourself be the judge, and take risks against aged product and potentia l failure on your own.

Peter Wieck Melrose Park, PA

One more thing I've noted.

Some manufacturers really have their sh*t together better than others, and it shows. I have had unopened tubes of sealant fail, and in a couple cases I cut them open out of curiosity.

What I found is that the failure inevitably stems from a bad seal or crimp. You can literally see and feel the substance harden starting from a specif ic point. On metal tubes, it's been the bottom crimp. Poor or worn tooling will create a stress point in the crimp that can cause a seal breach. This is where air and moisture enters, and you can follow the hardened material from that point further into the tube. Plastic squeeze tubes can suffer a s imilar failure from the heat crimp.

On caulk tubes, the failure is usually at the bottom, the insert that gets pushed in by the caulk gun. Run your finger around the inside of the tube -

- if you feel ridges or rough spots, this is where the seal can breach. Oft en the caulk hardens there and then the tube will no longer be usable -- ca n't push it in -- even though the majority of the material in the tube is s till viable.

I've even had tubes rupture when I tried to push past the cured material. A nd I've ruined a cheap caulk gun that way.

The all plastic tubes seem more prone to fail than the foil lined cardboard tubes, at least as far as product going bad. It doesn't make sense, those tubes are one piece. But I think the interior surfaces are not as smooth.