These test methods all assume that the label material meets the test method’s sample width requirement, which is typically 24 mm (1 in.) wide. In addition, the usual test duration is based on a label sample of a length suitable to apply 96 mm (4 in.) of the adhesive-coated side of the label sample to a standard test panel.
However, many converted labels are narrower (and, in some cases, shorter) than the test method requirement specified. This does not mean the labels cannot be tested; rather, some procedural steps must be modified in order to obtain relevant data and results.
Test results obtained when using the modifications described in this article may not compare exactly to those attained when testing labels of the same material of the full required dimensions. There are some inaccuracies built in to the testing of narrow labels.
As noted, converted labels that are narrow in width are frequently short in length. This will cause problems, as the sample is not long enough to place one end in the jaws of the testing instrument while the other end is adhered to the test panel. In this case, a small label must have a “leader” attached to one end to facilitate this operation. This can be accomplished by using an aggressive masking tape, a packaging tape, or, for difficult-to-adhere-to labels, a silicone splicing tape (see Figure 1) as a leader. The exact length of the leader is not crucial; it just needs to be long enough to allow slack in the leader when the sample is placed in the test instrument jaw.