Blister Cards: Not For the Faint of Heart
You see them everywhere. They are in bait shops, hardware and grocery stores, pharmacies, and almost every possible retail outletâ¦ what I am talking about is the handy and ubiquitous blister card, those little paperboard and plastic packages that both seal and display the actual product while hanging from a type of display. Because of their abundance it would be safe for the average consumer to assume that producing blister cards is a simple process. This, I can assure you, is not the case; there is a lot of research and testing that went into developing this capability, and each run requires constant monitoring to assure the individual sheets donât stick together turning into a giant block of paperboard. An even more devastating possibility – having the plastic blisters not seal to the backer card! I am certain that retailers are never happy seeing their merchandise falling out of their packages out on the store shelves.
Retailers like blister cards because they clearly display the product for sale, and provide plenty of space, both front and back, to describe the productâs attributes and other necessary information. They seal tightly, which helps reduce theft, and they are safer and easier to open than plastic clamshells. Special laminates may be applied to the paperboard to also make it tear-proof, and thereby more secure.
To successfully produce blister cards the printer must understand the type of blister used and the method of application. A few of the most common blister types are Polyvinyl chloride (PVC), Polyethylene terephthalate (PET), and recycled PET (R-PET). PET and R-PET are gaining in popularity due to their recyclability. In any event, the printer must know the type of blister to be used because this will determine what type of over coating to use on press. Each blister requires its own type of coating. The two methods of sealing are either by heat or radio frequency.
Knowing the type of blister being used allows the printer to specify the type of over coat material. Besides using special types of coating, printing blisters requires a special grade of paperboard material, blister specific inks, properly specified anilox rollers, and very tight process controls. Although the coating can be applied on a separate pass, printing all of the colors along with the coating in a single pass is more efficient from both a timing and cost perspective.Â
When removing a sealed blister cavity from a backer card, you should then see a significant amount of removal of the outer lining of the paper from its back. The term for this is fiber tear. The problem for the printer is that there is no way to test for fiber tear during the printing of a blister run. Other tests must be performed to ensure that fiber tear will be possible during the sealing process. The coating weight and temperature must be maintained at pre-determined levels, and constantly monitored during the production run. Load height must be kept at a minimum. The testing methods involve a combination of highly sophisticated measuring equipment as well as using simple tools that can be found around the house. These tests go over and above the constant color evaluations a pressman performs on any typical job. The point is, the possibility of failure is too high not to watch for possible errors.
No matter how good you get a printing blister cards, it will always be more stressful than printing any other type of product. As it should be, all the final customer cares about is the actual product they purchased, with little to no regards for the package other than if it is difficult to open or dispose of. The blister card is both easy to open and to dispose of. Itâs kind of a shame that only a tiny percentage of people know and appreciate all the engineering and skill that went into making them.