Closure stability is tops on upside-down packages: engineering a closure for an inverted package also requires attention to proper sealing, functional dispensing and costs - Closure For Inverted Packages

Food & Drug Packaging, July, 2003 by Lisa McTigue Pierce

At last, American consumers have opened their minds--and homes--to upside-down packages for foods and personal care products. Ketchup, mayonnaise, salad dressing, dipping sauces, peanut butter, shampoos, conditioners, toothpaste and other products have recently seen sales spike by using their head--the head (or top) of their package, that is.

Inverted packaging is an effective way to differentiate and/or reposition your product. Just look at the "new" ketchup products from ConAgra (for its Hunt's brand) and H.J. Heinz. Nancy Kane, marketing coordinator at Zeller Plastik, a Crown Cork & Seal Co., says, "You can take a ketchup bottle that's been Heinz 57 for 10 years, turn it upside down and put a label on it and it's almost like it's a new product--at least in the consumers' eyes. That's really what marketing is all about, catching the consumer's eye. That's what a lot of this inverted packaging does."

Stability is critical for an upside-down package, with performance resting squarely on the closure. But stability isn't the only technical challenge in designing and developing a closure for an inverted package. The closure must also provide functional dispensing and adequate sealing. It should deliver special marketing options, such as embossing or debossing, multiple colors and cap/container orientation. And, of course, it must make sense financially.

All together now

When creating an inverted package, it's important to match the closure with the container, whether that's a bottle, tottle or tube. Jeff Minnette, vice president of sales and marketing at Rexam Closures & Containers, explains, "The package has to be weight-balanced when it's full or empty. It's not as simple as just building a bottle and then, at the last minute, throwing a closure on it. This has almost got to start with the closure and then build the package around it. I can't stress the importance of integrating the package and closure together up front. Don't commit to bottle tooling and then design the closure."

Putting an inverted container and closure together truly is a balancing act. According to Tina Carlson, senior packaging engineer for the new inverted Wish-Bone Ranch Up salad dressing from Unilever Bestfoods, "The main challenge in designing a closure for an upside-down package is knowing how large your footprint needs to be to keep a package stable. Bottle manufacturers have CAD/CAM programs where they can determine where the center of gravity is going to be in the bottle. That can help to determine how big you need your closure to be."

Some food products introduced recently in upside-down packages need fairly large closures because of the container size. Susan De Groot, market manager for Food and Beverage at Seaquist Closures, explains, "There's so much more volume [in these containers]. We don't want to go so big that it would be a cost-prohibited closure, but we don't want it to be too small that's not going to lend enough support to give it the stability it needs in the inverted position."

Jameson (Jamie) Stull, manager of sales engineering for Stull Technologies, looks at the weight issue for both foods and personal care products. "As the container--a tube or a bottle gets--larger or heavier or you vary the shape, you've got to give it a good base to stand on," he says. "The diameter of the cover cap is the critical proportion."

Lastly, the lid needs to be flat, at least along the rim, and should evenly distribute the weight of the package.

Valve vs. no valve

After stability, the next most important function of these closures is dispensing. Product viscosity, closure performance and cost can help you decide whether to use a self-sealing valve or not. According to De Groot, the silicone valve closure--which has been available in the U.S. for at least 10 years--has really opened the door to inverted dispensing. Many products that were too runny for a dispensing closure on an upside down package can now eliminate leaks and provide controlled dispensing.

Depending on the product's viscosity and the amount you want dispensed with each squeeze, you can tailor the valve slit size and geometry. Generally, the thicker the product, the large the slit. Seaquist Closures, Stull Technologies and Zeller Plastik supply valve closures, but none were eager to share their proprietary methods of how they help a customer select a valve for a particular product.

According to Stull, the valve must also be carefully integrated into the base closure. "You don't just put a valve in it and say it's not going to leak. Constant weight over time will allow the product to seep through--even a valve," Stull says. "There are things that you have to do to support the valve."

John Ziegler, marketing manager at Alcoa Closure Systems Int'l, says his company is developing what he describes as an improved valve design. Samples should be available by early 2004. Smoother dispensing is the goal. "As containers empty, you have to squeeze harder to evacuate the product," Ziegler says. "This airlock may require a higher push ... too high, maybe. The product can spurt sometimes once the valve does let go."