Tape is tape. If it sticks, that’s good enough for me” to which I usually respond: “If it’s good enough, why are your people putting 3 pieces of that on that box?”
In 20+ years of selling packaging, I can’t tell you how many times I’ve replayed that tape (pun intended). Fact is, in many situations any tape will work. But in most situations, the right tape works better, saves time and money. So, what’s the right tape you ask? Get ready because this will blow your mind. The right tape is the one that keeps your box closed until it gets where it’s going.
Sounds simple, right? If only that were true. There are so many kinds of box sealing tape; too many to name here but I can boil it down to this: there are two kinds of tape – water activated paper gum tape and pressure sensitive packaging tape.
Water activated tape, gummed paper tape or gummed tape is usually a starch-based adhesive on a kraft paper backing which becomes sticky when moistened. It’s sometimes embedded with strands of fiberglass that reinforce and increase its strength. The history of gum tape may go back as far as 4000 B.C. when, according to archaeologists, broken earthenware pots were fixed with cloth and adhesive substances made from tree sap. These days, it is used when the ultimate in strength and/or recyclability is needed.
Pressure sensitive adhesive tape is made of a pressure sensitive adhesive coated on to a backing material made from paper, plastic, film, cloth or metal foil. It’s sticky without any heat or solvent activation and adheres with light pressure. Adhesive tape as we know it was invented in 1925 by a scientist working for the company that became known as 3M. It was known as “Scotch” brand tape and became a generic brand. In Europe, the same kind of stuff is known as “Sellotape.”
Pressure sensitive packaging tape’s strength comes from a combination of the makeup and thickness of its two main components – the backer and the sticky adhesive. The most common backer material is polypropylene. The most common adhesives are made from resins that are solvent-based acrylic or rubber (either synthetic or natural).
As with any packing tape, when applied to a corrugated box, the adhesive flows in to the paperboard’s fibers. This is what gives tape its “bite.” Water activated adhesives bite the fastest and harden when they dry. Think of glue. Pressure sensitive adhesives bite more slowly at first but strengthen over time and remain flexible and to a certain extent, stretchy. The thicker the adhesive, the more it will flow in to the paperboard fibers. The thicker the backer, the stronger the tape.
This brings us back to picking the right tape for the job at hand. There are lots of scientific testing methods developed by ASTM and other organizations. In my experience though, the best way is through trial and error. For instance, I once had a customer who filled a bladder with 40 liters of liquid, put that bladder in a box and shipped it out. They had been using hot-melt glue applied with an industrial glue gun. We taped several boxes with different kinds and thicknesses of tape, hung them from pallet racks and waited to see which would fail first allowing the bladder to fall on the floor. At the end of the test, a couple of boxes were left with the corrugated tearing from where we hung them but the tape still intact.
Generally speaking, if you’re not going to use reinforced gum tape, a 1.8 mil – 2.0 mil polypropylene tape with acrylic adhesive will work in most situations. If you’ve got a heavy box filled with something like brochures, you might want to go up to a 2.2 mil or 2.5 mil. That’s good for industrial uses. For retail, where the boxes may suffer more handling and abuse, a 2.5 mil up to a 3 mil or more may be necessary. Again, if you’re not going to use a super scientific process, trial and error is the best test of all.
There have been entire books written on tape, which to use and how to use it. But as you can see, tape is not just tape. There is no “one size fits all.” The right tape is the one that keeps YOUR boxes closed until they get to where they’re going.