: I think you might be using mylar, which is a polyester plastic. The simplest
: way I've been able to tell the difference is by lightly scoring the
: plastic with an xacto knife or single edge razor blade. Apply no more
: pressure than you would use to write with a pencil or ball-point pen. Then
: flex the plastic. Acetate breaks sharply and cleanly when gently bent,
: while mylar and similar polyesters need to be flexed several times and
: then may give a ragged edge. Polyester and mylar have pretty much taken
: over the market for acetate, but when I needed to cut a stencil, or a mask
: for airbrushing, I'd go with real acetate.

I tried your scratch and bend test and the results say 'mylar'. I checked the Pygmy Contruction Manual Packing List and it says "5' x 4" strip of mylar". My mistake, sorry, I'm a bad man. I hope I didn't mislead anyone. Never mind...

My reason for looking for an adhesive that would bond to both PVC and epoxy was that I was trying to install a 6" plastic day hatch in my epoxy over wood deck. I found several products whose label verbage was hopefull enough for me to purchase and test the adhesive, but all caveated "Test It" in the small print. Also I tried things that marine store salesmen suggested. Nothing adhered well to the PVC hatch. I ended up installing the hatch by bedding it in liberal amounts of 3M 5200 and fastening it in place with 5 #8 nuts and bolts. (That 5200 is messy stuff, it gets everywhere! I hope I never have to use it again.) The hatch, however, is a beautiful thing. I would do another day hatch on this winter's boat but Nick has placed the aft hatch on the S&GNH within reach, especially if I mount it with a hinge and a couple cam latches.

Since then I found that applying a blow torch to plastic for a moment (not enough for any melting or damage or discoloration) temporarily causes the molecular structure of the plastic to become more cooperative in the bonding process. This method is used to apply epoxy/fiberglass patches to repair plastic (PPE) kayaks.

: Well, what is the plastic you are trying ot bond to? If you are not thinking
: of teflon or polyethylene, there are a LOT of adhesives out there which
: might work. There are some new urethane-based glues which are pretty
: awesome. Look at the hardware store need the cunstruction adhesives like
: Liquid Nails. The "crazy glues" (cyanoacrylates) can work, too.

: How strong of a bond do you need? In most cases adhesives can be rated by how
: much tugging is needed to separate things when the bond area is one square
: inch. When you can't get a better rating on the PSI (pounds per square
: inch) scale you can sometimes improve on the bond by roughing up the area,
: effectively increasing the size of the bond area, or making a larger bond.
: Of course if you flex the bond and one piece is more flexible than the
: other you can effectively be putting a lot of pressure on a small area,
: thus exceeding the "strength" of the adhesive. I

: Theoretially, if you could cover a large enough area with the adhesive from
: post-it notes you could lift a car -- but that would be a very large area,
: and you wouldn't want to have someone start peeling the bond away from an
: edge.

: PGJ