STRENGTH:
There are many types of adhesive, which are manufactured with a specific range of desirable properties and characteristics in mind. One of the key characteristics of an adhesive is its permanency, i.e. whether it is designed to be a permanent or removable adhesive. Adhesives range from extremely strong permanent adhesives to very light removable adhesives, and each adhesive has its own unique level of initial tack and ultimate tack.

Tack refers to the “stickiness” of a material; the quality that allows immediate adhesion between two surfaces with a minimum of pressure and contact time, while the adhesive is in a fluid or semi-fluid state. Initial tack describes the strength of the bond that is created the moment a label is applied to a surface. After a label is applied the adhesive will harden and set; the strength of the bond between a label and a surface when an adhesive has fully set is known as the ultimate tack.

If you want a self-adhesive sticker that will create a strong, permanent bond with a surface, you will need an adhesive with excellent initial tack and excellent ultimate tack for long term adhesion. Alternatively, if you want a temporary label that is easy to remove when it is no longer needed, you will want an adhesive with low initial tack and low ultimate tack for short term adhesion.

TIME:

All adhesives strengthen over time; when a label is first applied, the initial bond will strengthen until the adhesive sets into its ultimate adhesion. You should always allow labels time to set properly before testing the strength of the adhesive; many people will become tempted and try to peel up a corner of the label soon after it has been applied – some then believe that the adhesive is too weak for their purpose, when they simply haven’t allowed enough time for the adhesive to reach its ultimate tack.

This factor should also be considered when choosing removable labels or when considering purchasing labels that will be stored for future use. Removable adhesives are designed to have low initial and ultimate tack so that – when the label is no longer needed – the label will remove cleanly and easily from a surface. However, if a removable label is left for very extensive periods of time, the adhesive will eventually harden into a more permanent bond. Labels that are stored for extremely long periods of time may also begin to set before they can be used. To avoid this, labels should be stored in a cool, dry place out of direct sunlight and should be used within their recommended shelf life.