SPMC's FAQs provide guidance for your technical challenges.

I am looking for information on the round robin testing performed on seal strength testing detailed in ASTM F88. Could you help me?

Last Updated On January 27, 2026

This subject was discussed in detail in an article, written by the SPMC Technical group, published in the January 2006 issue of Pharmaceutical and Medical Packaging News. Below is a summary of the section on the round robin referred to as the Interlaboratory Study (ILS).

The protocol approved by the then current subcommittees was designed as three independent round robins of 6 labs each. All testing was based on the use of seals designed to be peelable. Each segment of the ILS required a total of 30 seals be pulled for each technique.

Test series “A,” a focus on a coated material tested a paper/film combination for differences in speed of cross head travel and on two different techniques of tail angle of peel.

Series “B” incorporated an uncoated material with the 1073B Tyvek®/film combination keeping the crosshead speed consistent while again varying the control of the tail angle of peel. In this series, both the average and the maximum of measured values were reported. An additional test called “reverse direction” was geared toward demonstrating what occurs when the less flexible material is bent back and the more flexible material was held supported by the backing plate.

In test series “C” a sealant material common to the two substrates of different caliper (foil 5 mil and film 3 mil.) was sealed face-to-face in an effort to measure the effect of a change in flexibility to the measured value when tested unsupported and supported 180 degrees. The table below summarizes the details for each test series.

Test Series “A” (Peak Values Only)
Heat Seal Coated 50# Basis Weight Paper sealed to Film (48 ga. PET/2 mil LDPE)
Supported 90o @ 12”/minute
Unsupported @ 12”/minute
Unsupported @ 8”/minute

Test Series “B” (Both Peak Values and Average Peel Values were reported)
Uncoated 1073B Tyvek® sealed to Film (48 ga. PET/2 mil LDPE)
Supported 90o@ 12"/minute
Unsupported @ 12”/minute
Supported 180o @ 12”/minute
Reverse direction of mat’ls in grips @ 12”/minute

Test Series “C” (Peak Values Only)
Coex HDPE 3 mil film with peelable sealant layer sealed face-to-face
Foil Composite 5 mil with same peelable sealant surface sealed face-to-face
Unsupported @ 12”/minute
Supported 180o @ 12”/minute

Since the initial ILS, ASTM F88-23 Standard Test Method for Seal Strength of Flexible Barrier Materials has been expanded with information in both annexes and appendices regarding the impact of variation on sample width and grip separation speed and an addition of techniques for testing peelable heat-sealed lid samples from thermoformed trays. This substantial section of the standard showing images of tray holding jigs and sample cutting jigs is supported by an in-depth ILS. Each ILS is supported by a Research Paper maintained by the ASTM ILS group. The initial three-page F88 document from 1968 has now become 20 pages of current and valuable insights into seal strength testing.