Zip It Up
By Tom Wray, Associate Editor

Zippers and closers are becoming more useful and common as technology advances.
When a consumer goes to the supermarket, many of the products that are available come in bags. Unlike the packages of past decades, today’s bags are often resealable thanks to advancements in the creation of zippers and sliders.
As zippers and sliders become more common in packages, especially with consumers who only need to use a part of the product and save the rest for other meals, manufacturers are working to develop new ideas and technologies.
Zippers, the press-to-close technology, tend to be more popular on many products available today.
“Zippers are perceived by some as being better because there is no extra little tab of plastic [that could] break off, as is the case with sliders,” says Ken Hynes, vice president at Carroll Manufacturing and Sales. “And when that piece breaks off, the pouch won’t seal or stay sealed.”
Another plus for zippers is that manufacturers have more flexibility on where to put the zipper, he goes on to say. Sliders, with a plastic piece that close the seal and lock it down, can only be placed at the top of a bag. Zippers, on the other hand, can go one-half to three-quarters of an inch below the top of the bag, allowing for the bag to have a heatseal for placement in the store or notches for hanging in a display.
Elizabeth Sheaffer, marketing manager at Zip-Pak, says that zippers are also cost-effective, with no extra parts or machinery needed to include it with the package.
“However, new research indicates that consumers are willing to pay a premium for products that offer a resealable slider closure on their packaging,” she adds.
Sliders are easier for consumers to use when resealing bags. Also, says Steve Meli, marketing manager at Pactiv, sliders offer a better chance of closing the bag with a positive seal each time.
Variety of products
The kinds of products that can have zippers and sliders on packages are seemingly endless.
“It’s really a matter of customer preference,” says Hynes. “Pouches that will be opened and closed many times (beef jerky or cured beef) probably will hold up better with a zipper.” His own company has developed a metalized pouch for spiral sliced hams.
Meli says any package that is wider than seven inches with more than one use can benefit from using a slider, with larger bags from club stores such as Sam’s Club and Costco growing the fastest. He also points out that sliders can have a benefit with products marketed to the elderly, who may have a harder time reclosing zippers.
Sheaffer adds that being able to reclose the package keeps the brand where the consumer can see it on a regular basis as they use the product. The best closure for a particular instance depends on the product itself.
Any package with a poly sealant layer can use zippers and sliders, according to Meli.
Hynes says that for the work CMS does, with a focus on zippers, films that are more rigid work better than those that are softer or stretch, to which attachment of a zipper can be more difficult.
Pluses and minuses
Even as zippers and sliders become more and more common in packaging, there are some complaints that could come from customers.
“Press-to-close zippers can be very difficult to get into,” says Meli. “Also, depending on the quality of the press-to-close and the size of the package, press-to-close can be very difficult to reclose.”
Hynes points out that plastic tabs on sliders can break off, destroying any ability to open or reseal. Bags and pouches that use lighter plastic may also not hold up well with heavier items such as sliced hams or beef roasts. They can also be difficult for the young or elderly to open and close.
There are also things that processors need to keep in mind when using reclosable seals in packaging. For either closure, to add them to bags requires specialized equipment. Hynes says the bags his company produces uses a specialized pouch machine, for example.
“The type of equipment varies depending on the application,” adds Meli. “Form-fill-and-seal applications require an attachment to apply the slider. The retrofit for pre-made bags is very minor on the manufacturer’s filling equipment.”
Sheaffer points out that her company is able to retrofit machines as old as 30 years old with newer equipment that takes advantage of new closures and material.
Many meat packages, she continues, use a standard thermoform-fill-seal material. Most of the major packaging companies have equipment that can incorporate and run new zipper and slider technologies on existing machines.
She also points out that customers select a company that they can trust when switching to resealable packaging.
“It is essential to make sure that you have all the information and equipment needed to make educated decisions,” Sheaffer says. “A specialist can help make a smooth transition to resealable packaging, and can recommend partners such as film suppliers and OEMs.”
And the most important things, Meli adds, is to make sure the addition of resealable packages on the line don’t slow down the process.
Moving forward
Suppliers are still working on new technologies to make zippers and sliders useful for a range of products.
Hynes says that CMS has been working on zippers that are more heat-resistant to allow for cooking, boil-in-bag or reheating applications. The company also is working on ways to make zippers work better for customer-requested heavy-duty applications, for instance.
Zip-Pak is working to improve their technology specifically for the meat industry, Sheaffer says, creating packages that are easier to use while still maintaining a protective seal, especially important for oxygen-sensitive meats, such as deli-sliced ham and turkey.
“Nearly 20 years ago, the meat industry recognized the brand-differentiating benefits of resealable packaging,” she says. “The convenience, freshness and branding benefits have convinced the meat industry to transition toward the user-friendly format.”
She adds that the trend continues with more growth in products such as hot dogs, sausages, ground meats and bacon. Since these meats come in multi-serve portions but are not consumed as frequently, the packaging can enhance convenience and maintain freshness. Hynes believes that more items will find their way to zippered pouches.
“It’s all about offering convenience to the user,” says Hynes. “Zipper pouches are being used for many applications that used to require a can, such as tuna. Stand-up zipper pouches are now being used for precooked rice dishes and other items that will be heated for consumption right in the pouch.”
Sheaffer also believes that zippers and sliders will continue to grow more popular in foreign markets such as Asia and Europe. Her company, Zip-Pak, is also seeing a rise in resealable packaging in Eastern Europe and South America, especially with products such as dried milk, powdered soups and spices.
“Our customers in those markets are finding that switching to resealable packaging is often not a large investment, and [they] have also seen a dramatic rise in sales after they employ the zipper on their consumer product packaging,” she says. “We believe this trend will continue as brands recognize the ease of transition — often with little to no interruption to the packaging line — to a press-to-close or slider zipper.”