Seal attributes can be linked directly to a number of variables in process parameters, equipment, or material, as well as environmental (room temperature and relative humidity). Visual seal characteristics and defects can provide evidence of package integrity and production sealing problems.

Visual seal defects often will be the first indication of heat sealing process variation. They also will indicate a lack of, or potential compromise to, package integrity after physical package performance testing.

1.1 This test method covers the determination of channels in the package seal down to a width of 75 μm [0.003 in.] with a 60–100 % probability (see Section 8).

1.1.1 The ability to visually detect channel defects in package seals is highly dependent on the size of channel, the degree of contrast from sealed and unsealed areas, the amount and type of adhesive between the two package layers, reflecting light angle, types of material used, the use of magnification, and the inspector's level of training and experience.

1.2 This test method is applicable to packages with at least one transparent side so that the seal area may be clearly viewed.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.