subject: Seam Sealing Tape Standard Testing [print this page] Most people would expect a garment that had a label of 'waterproof' to completely protect them from the elements. This sometimes isn't the case. In the industry of textiles, there is a sliding scale of waterproofing. While many professional garments are given a higher rating due to the use of seam sealing tape, civilian and recreation garments have a lower rating and are less waterproof than those with the higher rating.
When waterproofing was new, the original process was the layer fabric with a solution in between. This created a relatively waterproof garment, but while it protected the interior fabric, it's exterior layers absorbed all the water. Now, modern waterproof garments are all about light, efficient and breathable fabrics and a focus on the use of seam sealing tape to lock. This locks out moisture on the exterior, but the lightness of the fabric allows for the wearer and the interior fabrics to release moisture out of the garment.
Fabric is not completely waterproof. Materials like metal, glass, formulated rubber and other solid objects are completely waterproof. Fabric is just very highly water resistant. In the manufacturing and testing process, garments are put through tests to determine how waterproof a garment is, and then given a rating based on the findings. Ratings are based on two different criteria
Rain Room Endurance Testing - One of the tests they use to determine a rating is the rain room endurance test. This test simulates how a garment will withstand rainfall and is used to begin to determine its rating.
Static-Column Testing - This is the test to measure the absolute water resistance of the entire garment, focusing on the exterior surfaces. Using a pounds-per-square inch conversion, or standard millimeter measurement, a tube with a one inch diameter is placed vertically on the garment. It is then filled with water and over a period of time, that water is measured to verify if any has leaked through the garment.
The results of the tests are articulated as 20,000mm waterproof or 20K mm. This may not make much sense the average buyer, but once you understand how and why the tests are run, you may be able to make your choice.
The results from these tests are combined by companies to put a garment through situations as close to real life as possible. They test how well a garment will stand up to light conditions (a rain storm), medium conditions ( a severe thunderstorm) and heavy conditions (water breaking over the side of a ship, fire fighters, etc.)
There is a drawback to laboratory testing though, and that is that real life situations vary immensely. It would be impossible to measure every possible variable in the lab.
To counteract that, researchers are working to improve the technology. Waterproof garments and seam sealing tape are continually being put through tests and improvements to ensure that moisture does not leak through the seams which are the weakest point of a garment. The seam sealing tape that is the most advanced and sophisticated utilize powerful adhesives (no PU adhesives) that can stand heavy moisture combined with heavy use. This provides the highest quality waterproofed garments and gear for use at work and in the field.
