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  • Writer's pictureSamantha

The Difference Between Seal Strength and Seal Integrity


If you are in the food, manufacturing, or pharmaceutical industries, you know the importance of testing your packages for defects and leaks. A small defect in packaging can cause the deterioration of your product, potentially rendering it defective and unfit for consumer use. However, while the importance of package testing methods is widely known, there is still some confusion between what tests accomplish. Specifically, the difference between seal integrity and seal strength tests. In this article, we will outline the differences in these tests, their applications, and how the use of these types of tests can benefit you and your products.

Seal Strength Testing

Seal strength testing refers to measuring the mechanical strength of a seal, and does not necessarily test the integrity of the overall package; rather, it relates to the force that is required to separate components of a package, and often is only completed on small sections of the proposed packaging. Strength tests are typically effective when testing the force needed to separate two flexible package components, such as those found in a pouch, or a flexible lid and thermoform tray.

Seal strength testing allows manufacturers to determine on a daily basis that the package sealing process is consistent with necessary specifications, especially in industries that are tightly regulated with specific testing standards that must be reached. There are numerous types of strength tests that can be performed, including burst testing, which is measured in pounds per square inch.

Seal Integrity Testing

Seal integrity testing, on the other hand, tests the entire package to ascertain whether or not it will remain intact when subjected to external forces, protecting contents from damage and maintaining sterility. As such, seal integrity testing is not only important in determining the strength of a package, but also in determining the sterility and shelf life of a product. The package’s seal must be evaluated based on exposure to environmental and dynamic stresses that can be expected to impact the finished package, such as distribution, storage, handling, and aging.

In many industries, such as medical and pharmaceutical, it is extremely important that products remain sterile. Seal integrity testing is extremely important in such cases, as it will be able to ensure that not only is there a sealed microbial barrier created in a post-sterilization environment, but that such a barrier will hold throughout the product’s lifespan. A microbial barrier that can stand up to extensive seal integrity testing will be able to protect medical products from contamination in a variety of conditions.

Seal Strength vs. Seal Integrity

So, what test is the right choice for you? At first glance, package strength may appear to meet the requirements to ensure the integrity of your packaging. In fact, it has limitations. Alone, package strength does not necessarily prove the integrity of an entire package, as it tests only a small portion of the package. To be effective, strength testing should be paired with additional testing to ensure the quality of your package.

Seal integrity testing, on the other hand, evaluates the material’s performance as a whole, determining the quality of the complete, finished package rather than simply testing part of the package as is seen in seal strength testing. Seal integrity testing will ensure that your package can withstand a variety of pressures, maintain sanitization, and improve product quality throughout its lifetime. No matter the product, including seal integrity testing in your manufacturing process will help to create a robust, comprehensive quality-testing program.

Seal-Check Test Methods

Seal-Check provides several seal integrity testing solutions to suit your needs. Our diverse seal integrity tests can ensure your packages meet the required ASTM testing standards in your industry, with the ability to test a variety of product and packaging types.

Bubble Leak Testing: Bubble Leak Testing is completed in an acrylic vacuum chamber. The sealed product is submerged in water and, when put under pressure, bubbles will form at any compromised points in the packaging. Bubble Leak Testing is an easy visual test that will ensure your packaging’s integrity while adhering to the ASTM D3078 testing standard.

Detecting Gross Leaks in Packaging by Internal Pressurization: The ASTM F2096 Testing Standard provides highly accurate testing for pharmaceutical and medical packaging, allowing users to detect leaks, substrate holes, and channels accurately and reliably. The sensitive nature of this test means it can detect leaks that a standard Bubble Leak test cannot, and it can also be used with a variety of package shapes and sizes.

Altitude Simulation Testing: Altitude Simulation testing, the ASTM D6653 testing standard, is a package integrity testing method that simulates the extreme pressure changes a package may undergo during transport. An altitude test will simulate ascent and descent rates, as well as a set altitude for an extended period of time, ensuring that the packaging can withstand its transport and reach consumers intact.

Dry Chamber Tests: A Dry Chamber Test is performed without liquid in a leak detector tank. This procedure is best suited for packages containing liquids, such as condiment sachets or bottles with lug-style and threaded caps. The package is placed within the chamber on an absorbent material and, when put under pressure, any leaks will result in the presence of liquid within the dry tank. The ASTM D5094 testing standard is performed in a dry tank environment.

While both seal strength and seal integrity tests are important when manufacturing product packaging, it is important to understand the strengths and limitations of each individual test. Though similar, each test has a separate application and will affect your packaging quality in different ways. Seal-Check offers custom leak testing and seal integrity testing solutions to ensure your packaging is at its best and can work with you to find the best equipment to meet your needs.

From fruit to pharmaceuticals, meat to medicine, and anywhere in between, Seal-Check is the most reliable solution when it comes to package seal integrity and leak testing equipment. Contact us now at +370 689 24325 or visit us at for more information or to request a quote.



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