bEHIND THE SEAMS
TESTING AND SCIENCE
How do we calculate WARMTH?
Using recognised scientific testing methods, we continually compare and test our welded seams against comparable alternatives. We use Intertek, a renowned, independent third-party quality assurance provider, to do the testing for us. They test comparable sewn and welded panels to determine which retains heat the best.
In a recent thermal resistance test, we created two identical down-filled pillows under BS EN31092-1993 guidelines. The only difference was the seam construction; one pad used Stealth™ welded seams, whilst the other was constructed using a comparable stitched alternative. Both samples used the same 100% Nylon woven fabric, weighing 62gm/sqm, and filled with the same 90% Grey Goose downfill using a baffle box construction.
The results were outstanding;
Stitched product warmth returned an insulation rating of 1.2 CLO – our Expio Stealth™ welded seams returned an insulation rating of 3.3 CLO*
With no puncture holes caused by the needle in stitching, our welded seam panel was over 90% more insulating than the stitched alternative. As a result, our Expio styles may be made using less insulation, meaning we can create lighter styles with the same or better level of insulation.
WHAT IS A
BOX-BAFFLE?
What’s CLO?
CLO is a value that describes the degree of insulation provided by an article of clothing. A CLO value of 1 equals the amount of clothing a resting human requires to maintain thermal comfort at a room temperature of 21 degrees Celsius, or 71 degrees Fahrenheit.
Used for our Down jackets
WHAT IS A
BOX-BAFFLE?
How do we test the STRENGTH of our styles?
We test the strength of our seams using a recognised pull method called a tensile strength test.
Specifically, we use an ASTM D1683 test method in seam engineering to determine the sewn seam strength in woven fabrics by applying a force perpendicular to the stitched seams until seam failure occurs.
The unit of fabric breaking strength is “Newton (N)”, which is used to evaluate the capability of the fabric to resist tensile damage.
In a recent test, we created two identical swatches comprising two parts, using the same 275gms 100% Nylon woven material. The only difference was the construction; one swatch used Stealth’s welded seams to combine the two parts, while a technician stitched the other.
The pull test was repeated by technicians in a laboratory three times, with the average breaking force noted in Newtons. The results were remarkable.
The stitched seam sample returned a tensile strength of 240.36N Our Expio welded seam sample returned a tensile strength of 385.03N
This particular test showed that our welded seams were 46% stronger in a pull test. The reason for this is simple: when seams are stitched, the sewing needle punctures holes through the material – these holes make traditional stitched seams prone to breakage and tearing.
