Thankfully I received several samples including one of silpoly. I made testing strip samples by glueing 27mm wide strips together with a 27mm wide glued overlap.Then I sewed on loops or hems to each end to provide anchor points for load testing. The addition of the hems was necessary because many of the fabric samples were too short to form hems on them.
The load testing was done by hanging a bucket off the test strip and loading it with 1-litre scoops of water as shown in the following video.
Glued silnylon load testing
Alas, my testing was a big failure as the fabric often broke before the glue bond did. I am reasonably certain that the fabric breakage was due to the stitched attachment of the hems.
We are often slow to publish failures as we may be struggling to understand the results or just too embarrassed . So, sorry for the delay and thanks to those that supplied the samples. Both success and failure hold valuable lessons so I report on these at last.
For most of the silnylons tested, the fabric failed before the glue bond did. This means that the glue bond supported a load between 4 and 8kg. One silnyon sample reached 13kg when the glue bond eventually broke as shown in the above little video. Perversely, this was one of my own silnylon (sample 9, grey) that I already knew had deficient bonding properties. So the true loading strength of the others could be very much higher.
I concluded that all the silnylons were capable of forming strong bonding with RTV silicone rubber (even my crappy silnylon). A better test method will be needed to find the true strength of the bonds. Such a method should avoid the use of stitching that could compromise the fabric strength.
Thanks again to all those who posted samples to me. For a more detailed report please follow this link.
Tim
