The Great Shelf Life Debate

This is the first blog post written from the retirement casa, deep in the north woods of Wisconsin. Actually I am only about 94% retired with some dabbling in consulting, industry events, and of course blog production. 94% ain’t bad however, and this writing assignment was bracketed by a stroll with the pup in the city forest and a kayak mission in the afternoon. Even so, it’s kinda fun to write about something that triggers both my well known cynicism and curmudgeonly nature, the insanity that has continued to spread regarding the shelf life of pressure sensitive label stock.


It was a little over five years ago that I wrote the first treatment of this topic. As predicted in the last paragraph, nothing has been done to address the problem. In fact, a couple developments have made it worse. I still get panicked emails about label stock that is one year plus three days and ‘can’t be used’. The really fun thing is now I just forward them.

The main fly that has dove into the ointment is that in order to address this non-problem, some device manufacturers have instituted a ‘remaining shelf life’ requirement. Basically this is a nonnegotiable requirement that states that any component with less than X% of remaining shelf life upon receipt will be rejected. This brings us right back to the root issue of when the shelf life actually begins. Does it begin when the adhesive is coated at our converter? Received at AWT? Manufactured at AWT? Shipped? Received at the device manufacturer?

The way to solve that issue is to keep the current system that many companies use: shelf life begins upon receipt.

Unfortunately, that does not seem to be the trend. Anyone that has added a shelf life requirement for packaging materials over the past couple of years has gone for date of manufacture, a date pretty easy to track since every one of our core or package labels has that date on it. The problem is dealing with blanket order, min/max, and kanban type orders. These are all really good methods to keep costs down and insure quick delivery. They are a really bad idea if the ‘remaining shelf life’ scheme is implemented.

On orders of this type, we would decide to run somewhere between a quarter and semiannual quantity. Semiannual would mean that last shipment would only have 50% of that year shelf life left, not acceptable under some of the requirements that I’ve seen. The easy way to be compliant would be for us to buy smaller runs of label stock at a higher cost and then revert back to the venerable run and ship, no matter what the quantity. Costs would go through the roof of course, but maybe that’s ok for something as critical as shelf life . . . .

Of course it’s not ok. It’s a stupid solution to what ought to be a non-issue. The best way to deal with this mess is to generate some data proving that the shelf life of modern water-based acrylic emulsion adhesives is about 4-6 times what the legal department of Avery-Dennison and the other big label stock converters say it is. We did the testing for one of our customers, per the blog post five years back, and discovered statistically insignificant differences between the 4 year old product and the new label stock.


Since all you device manufacturers need to generate your own data, I would think that some side-by-side testing of old and new material on 3 or 4 common substrates would be adequate. Peel, shear, and tack are the three measures of label adhesion to a substrate, and all have standard tests, whether they are ASTM, FINAT, or other standards. Since most of the warehouse and storage areas of device companies are climate controlled (or better be; label stock hates to get really hot and tends to ooze badly), the need for any hot and cold conditioning would seem to be precluded.

Four year old stock is generally readily available from AWT archives or our vendor retainers, both of which are documented and traceable. I know package engineering time is at a premium, but this would seem to have intern or entry level engineer written all over it. Cost justification would be not only perfectly good label stock scrapped but additional costs per unit of the above run and ship scenario. Double or triple that year of shelf life, and the cost of administering the shelf life BS would drop precipitously as well.

My guess is that discussion and implementation of this plan will roughly follow the sequence of events so well portrayed in the classic SNL Theodoric of York sketch with Steve Martin. Once everything is screwed up he delivers a passionate and analytical analysis of what should have been done and how things can be made better in the future. Folowed by the classic pause and then, “Naah!”

Good luck boys and girls. If you could find the time to generate the data, this could waylay a bunch of potential issues down the road.


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