What are release coatings?
Release coatings keep sticky things from adhering to paper or paperboard. Release can also be needed if a wet product—such as fresh or frozen meat—is capable of sticking to a container through drying or freezing action. Sometimes only a modest amount of release is desired, so things like temporary labels will stick but are still easily removed when desired.

Catalyzed release coatings are two-component systems: a separate catalyst is used to “set” a catalyzed coating. Single-component release coatings rely on heat to set the coating, and this heat-setting is less efficient than the use of a catalyst. As a result, catalyzed coatings tend to outperform single-component coatings, while single-component coatings are easier to use. Finally, catalyzed release coats are generally FDA-compliant, while single-component release coatings are not.

Why is release important?
In some industries—notably rubber—release is a major problem. Bulk units of hot, sticky rubber will become firmly stuck to their huge corrugated shippers if protective measures aren’t taken. While plastic bags have been used in the past, a release coating is cheaper and more effective by eliminating the labor involved in inserting the bags and then peeling them off of the rubber before it’s used. Many industrial food raw materials are sticky, too. And a wide range of manufactured products are packed and shipped before their paint finishes are fully cured, which is often a “sticky” problem.

How is release measured?
The Keil Test (TAPPI Useful Method #502) distinguishes levels of release by applying a tape to the coated sample and measuring the amount of pull necessary to remove the tape. A “Keil” of less than 100 is generally considered good, and less than 50 is usually needed for rubber release.