These practices cover laboratory preparation of heat seals. These practices also cover the treatment and evaluation of heat seal strength data for the purpose of determining heat sealability of flexible barrier materials. It does not cover the required validation procedures for the production equipment. Testing of seal strength or other properties of the heat seals formed by these practices is not included in this standard. Refer to Test Method F88 for testing heat seal strength. This practice does not apply to hot tack testing, which is covered in F1921. The practices of this standard are restricted to preparing heat seals using a sealer employing hot-bar or impulse sealing methods, or both. This practice is intended to assist in establishing starting relationships for sealing flexible barrier materials. Additional guidance may be needed on how to set up sealing conditions for flexible barrier materials on commercial/production sealing equipment. Seals may be made between webs of the same or dissimilar materials. The individual webs may be homogeneous in structure or multilayered (coextruded, coated, laminated, and so forth). Strength of the heat seal as measured by Test Method F88 is the sole criterion for assessing heat sealability employed in these practices. Other aspects of heat sealability, such as seal continuity, typically measured by air-leak, dye penetration, visual examination, microorganism penetration, or other techniques, are not covered by these practices. The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 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.