Storing tapes and films: temperature, humidity and shelf life

Ghee in a Jaipur kitchen runs freely in May and sets hard in January. The adhesive on a roll of tape behaves in a similar way. Heat softens it and cold stiffens it, and both change how well it sticks.

So the short answer is this. Store tapes and films indoors, in their original cartons, away from sunlight and heat, close to room temperature, and use the oldest stock first.

The tape manufacturers quoted below give storage ranges between 4 and 38°C, and shelf lives of one to three years from the date of manufacture. Films have their own limits, and some are much shorter.

Our plant is in Jaipur, so we work through the same summers and winters as our customers in north India. This guide is for the people who receive, store and issue tape in a godown. It covers what the manufacturers actually say, what temperature and humidity do to a roll, and the checks I suggest when stock arrives.

What the manufacturers say

Storage advice is printed on most tape data sheets, usually near the end. Very few buyers read that part. Here is what a few published sources say.

Two things stand out.

First, shelf life is not one number. Even within one manufacturer, it runs from 12 to 24 months across different products.

Second, the clock does not always start on the same day. Most tape sheets count from the date of manufacture. The stretch film sheet above counts from delivery.

I suggest you read the sheet for each product you stock, and write its shelf life on the rack label.

What heat does to a roll

High temperature softens the adhesive. Three problems follow, and you can see every one of them on the roll.

1. Oozing. The Pressure Sensitive Tape Council's glossary describes it as adhesive squeezing out from under the backing, which leaves the roll edges tacky. Tacky edges pick up dust and stick to the carton and to each other.
2. Telescoping. The same glossary defines it as the layers sliding sideways over one another until the roll looks like a funnel. A telescoped roll will not run properly on a dispenser or a carton sealer.
3. Cold flow. This is the slow movement of adhesive over a long time, as if it were a very thick liquid. Heat speeds it up.

In a north Indian summer, the space under a tin or asbestos roof can be far hotter than the room below. Keep tape cartons on low racks, away from roofs, from walls that face the afternoon sun, from windows and from anything that runs hot, such as compressors or heat tunnels.

What cold does

Low temperature makes the adhesive firm. 3M's data sheet for its 371 carton tape says the adhesive becomes firmer as temperatures approach 0°C, and that the tape goes on most easily at room temperature.

Firm adhesive grabs slowly. A packer running cold tape over a cold carton will see it lift, even though nothing is wrong with the tape.

We would call that a storage problem, not a tape problem.

The fix is simple. Bring the next day's rolls into a room at normal temperature the evening before. I would do the same with the cartons, if space allows. The Hipac stretch film sheet asks for the same care with film, and suggests keeping a pallet of film at room temperature for 24 to 48 hours before use.

If tape still fails on cold mornings, the troubleshooting guide has tests to find out whether cold is really the cause.

What damp does

The manufacturers' humidity ranges are wide, but none of them describes the open air of a monsoon week. Damp mostly harms tape through the packaging around it. Corrugated cartons soften in damp air, and a soft carton at the bottom of a stack lets the weight above press on the rolls inside. Water from a leaking roof or a wet floor can wick into a carton and reach the rolls.

Cold rolls carried into warm, humid air can also collect condensation on their surface.

Keep cartons on pallets, never directly on the floor, and a little away from outside walls.

Keep each carton closed until you need it. tesa's advice is the same: do not open tape you plan to use later.

How to stack and stand the rolls

IS 13262 tests the keeping quality of tape with the rolls stored on their cut edges, which is the flat side.

That is the right way to store them.

A roll lying on its round side carries its own weight, and the weight of everything above it, along one narrow line. Over weeks, that can leave a flat spot and a bump the dispenser feels on every turn. tesa also warns that pressure on tape products degrades the backing.

For film reels, the Hipac sheet asks you not to drop reels, not to tilt them when taking them off a pallet, and not to hit their edges or sides. A dented edge can tear when the film is stretched.

Films keep their own clock

Packaging films do not have adhesive to soften, but time and storage conditions still change them. Two kinds of film show this clearly.

Stretch film is one example. As the Hipac sheet above shows, one European manufacturer limits its stretch film to 6 months from delivery, much less than most tapes, and warns against sunlight, heat and chemicals such as solvents. Sunlight breaks down polyethylene film over time. Our own low tunnel film for farms is made UV stable for exactly that reason, because it has to live outdoors. Most packaging film is not made for that.

Film that will be printed or laminated has a second clock. Its surface is usually corona treated so that inks and adhesives bond to it. That treatment fades with time. A PRINTING United Alliance answer from April 2020 lists the causes: additives moving to the surface, handling, storage conditions and plain time. It notes that polypropylene films can lose much of the effect within 30 days or less. If you print on film, use the oldest film first and check its surface energy (dyne level) before a long print run.

First in, first out

All of this comes down to one habit, and it is an old one. Use the oldest stock first.

IS 13262 already asks makers to mark every container with the month and year of manufacture and the batch number. Use those marks. Arrange racks so that new stock goes in at the back and old stock comes out from the front, and write the arrival month on each carton in large letters if the printed date is small.

Checks when stock arrives

These take a few minutes per delivery. I suggest you give the job to the person who receives goods, with a short written list. The rule I would follow is simple: if a roll would not be good enough for our own line, it is not good enough for yours.

1. Read the carton. Product, size, month of manufacture and batch number should all be there and should match your order.
2. Look at the cartons. Wet, crushed or opened cartons deserve a closer look inside.
3. Look at the rolls. Check for sticky edges, a funnel shape, dented edges and crushed cores.
4. Unwind a metre from one roll. IS 13262 expects tape to unroll without adhesive transferring to the back of the turn below and without the backing tearing.
5. Keep one roll from each batch aside, labelled, until the batch is used up. If a complaint comes later, you will have something to test.

Reject or quarantine anything that fails steps 3 or 4. I would never put a telescoped or oozing roll on a machine, because a jam costs more time than the roll is worth.

A thermometer costs less than one bad batch

My last suggestion is the cheapest one. Put a simple thermometer with a humidity reading on the wall where tape is kept. Read it at the hottest part of the afternoon and note it in a register. If the reading goes past the manufacturer's range for days at a time, move the tape to a cooler corner, or move it closer to where it is used and order smaller lots more often.

This advice has a limit, and I should say it plainly. Few packaging godowns in north India can hold 21°C through May without air conditioning. So keep the rolls out of the worst heat, and use them before time catches up with them. For most packing jobs, that is enough.

If a delivery from us arrives with sticky edges or telescoped rolls, please do not run it on the line.

Send us a photo of the roll and the carton label, with the batch number, through our contact page. We will look into it and tell you what we find.