The Ultimate Shrink Sleeve Troubleshooting Guide
October 28, 2019
There are times in the life of packaging when you slow down and take all the proper steps to create a successful piece of packaging, but somehow, someway, you still run into trouble. Shrink sleeves are a very technical type of labeling and are no different. We are here to cover some of the most common issues that our customers (and Inland) have come across in our years in the shrink biz. Issues can vary based on container size and shape, film or ink selection, set up of graphics, converting steps, or sleeve application to name a few. Don’t cut corners, take the time upfront to trial your new material or container, because it will pay off in the end. Once you’ve done your due diligence, you may have some bumps in the road, but this shrink sleeve troubleshooting guide will point you in the right direction.
Flowering is when your shrink sleeve is curling away from the container. This can occur on either the top or the bottom of the sleeve. Flowering occurs when the film is shrinking faster than the ink. An important trick to incorporate into your shrink sleeve to safeguard against flowering is to leave a “no ink area” at the top and the bottom of the sleeve.
Why can I see the can peeking out below my sleeve? One of the most important selling points of shrink is the 360-degree coverage, so why is this happening? This is known as over shrinking. There are two factors that can be to blame for this happening – time and temperature – or a combination of the two.
The temperature in the shrink tunnel may be set too high or the time the container is spending in the shrink tunnel may be too long. Make adjustments for each of them separately to see if one or the other solves the problem. If that doesn’t alleviate the over shrinking, both the time and the temperature may need to be adjusted.
Well, friends, loose-fitting pants may be making a comeback, but no one wants a baggy shrink sleeve. That was a stretch, wasn’t it? In all seriousness, no one wants a sleeve that doesn’t fit nicely on their container.
For solutions to bagging, see above recommendations for over shrinking. Temperature and dwell times may be the leading cause and would need to be adjusted to alleviate the problems that you are having.
Wrinkling and Fisheyes
Fisheyes and wrinkling appear on containers when the warm film comes in contact with the surface of a container that is a cooler temperature. The varying temperature slows the shrinking process which causes fisheye patterns and wrinkles to appear on the sleeve in localized areas that do not have proper shrinkage. We find that the shrink sleeve’s heat source isn’t pushing enough air through when the heat is applied. Sometimes, tiny perforations in the plastic can be to blame for this issue. In that case, try to slow down the conveyor.
Frowning / Smiling
You can probably imagine what frowning and/or smiling may look like on a container. But to be clear, we aren’t talking about the shrink sleeves making you happy or sad. We’re talking about the sleeve shrinking up from the bottom of the container that gives the appearance of a frown. Or visa versa, a similar issue appearing on the top of a container giving the appearance of a smile.
The most common cause of this can be attributed to inconsistent shrink. Our field service representatives often troubleshoot through this issue by reviewing the heat tunnel. Making adjustments to the heat set point of the tunnel could help in alleviating the problem. Another option would be to add a heat-activated adhesive to the interior of the bottom (for frowning) or top (for smiling) of the sleeve to help pin down the sleeve during application.
Nothing is more frustrating than the sleeve not staying together. If the seams are busting on your shrink sleeve, it likely has to do with the adhesive that was (or potentially wasn’t) put on the seam of the sleeve. If this issue occurs, you should contact your supplier. It would be important to review the retains from the production job for proper adhesive laydown. Is there adhesive? Is there enough adhesive? Inspection is a portion of Inland’s finishing process to ensure that this is not missed.
Wet T-shirt or Sellotape
Why does it look like there is moisture behind my shrink sleeve? There are two potential causes for the appearance of moisture behind your shrink sleeves – often called wet T-shirt effect or sellotape – however, they are different issues entirely.
The wet T-shirt effect is a temporary issue that is caused by moisture that gets trapped between the sleeve and the container as it goes through a steam tunnel. Once the moisture evaporates, the wet T-shirt effect will no longer be visible.
On the flip side, the sellotape effect — although comparable in appearance — is actually a permanent issue. The wet look is more complex in the cause, as it is not caused by moisture. The sellotape effect is caused by the refraction of light when two very smooth surfaces come in contact with one another.
My artwork doesn’t match up at the seam
For brand owners and designers who are used to working with labels, other types of shrink sleeves can be a source of frustration. It isn’t often that our labels connect, so it makes sense that this step may be overlooked in the design process. Sometimes we sound like a broken record when we talk about how important graphics are for packaging to power your brand and stand out on the shelf, but your shrink sleeve design is no different. Designers need to recognize that shrink sleeves are three-dimensional and the design needs to come together or overlap at the seam and be considered in the creation of the artwork.
In terms of graphics, it is also important to consider UPC orientation and placement. The shape of your container can significantly affect where the best placement is for a UPC to ensure its scanability. Although we can traditionally compensate for shrinkage with the distortion of the artwork, it would be best to place the UPC in a low shrink area and to have the orientation be vertical, as the majority of shrink occurs in the traverse (horizontal) direction.
Shrink sleeving is all about using the right application and shrink tunnel technology, but it is important to realize there is no one-size-fits-all solution in the successful application and shrinking of shrink sleeve labels. Keep an open mind, and if you run into issues keep our shrink sleeve troubleshooting guide handy to point you in the right direction for adjustments to accomplish success. Most importantly, you are not alone. Never hesitate to reach out to Inland and utilize our field services representatives who work with labels and packaging 24/7.