I wrote an article once and referred to the "dreaded polylon" and several folks did not understand why.
Polylon is nylon cloth bonded to polyurethane and is made for colorful raincoats. It works really well for that but don't put it into a player piano or pipe organ.
I used the term "Dreaded Polylon" because I have spent more time in the last 20 years RE-Restoring instruments rebuilt with Polylon and Perflex than I have spent restoring original leather and zephyr untouched instruments.
These include pipe organs that were rendered useless in less than 12 years by the unholy holes in Polylon creases. I have replaced Polylon in red, yellow, blue, purple/gray, black and several others. I have samples of the cloths I took off after 5-12 years of use and they all show the poly falling off the nylon at all creases and corners.
The only Polylon I have not yet had trouble with is the solid purple both sides that American Piano Supply sells. I was once talked into using it by a previous boss, but I no longer use it I just don't want to take the chance. I only use what I have left to seal seams, holes, etc.
Polylon must be glued on with PVC glue but I have seen it crawl off the pneumatic boards after some months. The polylon does not stick very well and then seems to just start flaking the polyurethane off after several years
Yes, PVC glue is obnoxious to get off, but I just submerse the glued item to be re-restored into Lacquer thinner until the glue turns into what looks like blobs of snot. I can then easily rub the PVC_E off the pieces with my fingers.
Perflex was another synthetic material that was adopted by the rebuilding field in the 1970's. It looks like surgical glove material. It was first made for the US military so they could make water bags out of it and toss them out of helicopters to troops on the ground without breakage. It worked really well for that just about nothing would puncture it. There was lots left after the Vietnam War and it was tried on pipe organ and player piano pouches and worked very well. The one drawback, again, was the gluing of the stuff showed it crawling off months or years later. There was a way to bond it to paper rings so the paper could be glued down though and that was done for years.
Once the original batch made for the military had run out, folks had another batch made and while it looked okay, it was not good for pouches. After 6 years of flexing, those pouches would develop crescent shaped cracks in them rendering them useless.
Ask me why my shop never uses any synthetics of ANY kind. We use no modern materials that have not been tested for at least 30 years. No contact cement...it falls off in 5-10 years and turns dark brown, too. No hot glue guns, except for hanging hammers, but none of it stays in the piano. We use some PVC-E glue as it has shown its ability to hold up for decades of use. We also use no polyurethane varnish, it rots the wood from the inside out. The reason is we have to stand behind our warranty for five years.
Polylon sounded like a good idea but turned out to be a disaster
Doug L. Bullock, 06-22-09 Copyright 1997-2009