Kitesurfing, kiteboarding shop & school. Lessons - Durban, PE, J-Bay, Cape Town
After a good couple months of having my dining room table strewn with 20 different glues, expensive cleaning alcohol, test bladders (thanks Sin) and some other bits and pieces, I finally got to do the tests. I video documented a fair bit of it and maybe I’ll edit it together sometime.
I tested the polyurethane range of glues, like your Sestic cable glue and clear glues from most of the different manufacturers; there was about 7 of them that I tried. These are the glues that we have been using to date. Next was the different contact adhesives, about five of them. Then I gave the superglues a go, some pvc glues and a mix of some glues that I knew would not work but thought what the hell. Then also a couple that I had never heard of from obscure brands and that was a good idea as our winner came from that pool.
The tests were all done according to rigid scientific principles. Not, but what I did do was to give an equal playing field in that equal quantities of the glues were applied to two sides of the same bladder material. The material was cleaned with pharmaceutical alcohol and no roughening was done to the bladder material. My theory is that adding sandpaper to the mix would skew the results as it is hard to roughen evenly over a surface. I wanted purely chemical bond results. Mechanical bonding created by roughening the two surfaces would only increase adhesion in the end by the user thereby making the bond that much stronger. The tests proved that this was a good road to take.
A brief summary of the results is that the contact adhesives failed, the super glues failed and the polyurethane or clear glues delivered varied results but were, as expected, by and large the better glues. There were however two glues that stood out completely. A “Shoe” glue by Bostik and then the outright winner by a long shot “Vyna Bond” made by Performix.
Vynabond by Performix from what I can tell is an American brand, it can be used underwater, it looks and initially smells like a polyurethane clear glue, but like the Bostik “Shoe” glue it dries to a different smell. Clear glues have served us well till now but a general problem with polyurethane glues is that they don’t like too much heat and for the most part, excess heat is what is getting kite valves to separate from the bladders in the first place.
Out of all the glues tested Vynabond was far superior in its adhesion to the bladder material. Of the 20 glues it was the only one that adhered to both surfaces under limited weight pressure. All the other glues delaminated from one of the surfaces. It adhered so well that on separating, it tore out a circle from the bladder material.
The “kettle test” thanks Sin for this one, is the best way to bring heat (and water) into the equation without damaging the bladder material. (PS this is how you loosen old valves from the bladder; just hold them over a boiling kettle.) The polyurethane clear glues surrender their rights at this point in testing. The Vynabond was not affected by this test at all, so much so that I actually put the test patch into the kettle and stewed it around for a while. (The other glue that did well here although it originally delaminated on separation was the Bostik Shoe glue.) Vynabond’s stretch characteristics are also amazing. The glue seems to become one with the bladder, it’s impossible to get off.
Vynabond is available from Builders Express outlets. Tests are not completed yet, as a practical implementation is still to be put out there and I am yet to actually glue a valve onto a bladder. For patches and repairs already I can see it working, all you need is an old bladder to cut up and use as patch material or just use the glue itself for those pinprick holes. Performix’s Vynabond seems to be the answer, if you can’t get that one then Bostik’s Shoe glue is the next best, just roughen and clean the surfaces and you should be fine.
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