Bending plastic binding

[JLT]

I searched the archives and found nothing, but I'm sure this has come up before.

When a luthier friend of mine retired from the craft about ten years ago, I inherited some black plastic binding (0.08" x 0.22") and I figured I would use it in Jim Abbiati's cutaway OM guitar, which I'm finishing.

I usually use wood binding for my builds, but I was intimidated by the sharp bends of the cutaway, so plastic seemed to be a better option. When I used it on the back, though, the plastic was too stiff to make the bends without a great deal of force. It got better when I used a heat gun (on low) to soften the binding so that it would bend, but found that the binding would develop a twist that was hard to get out. Now that I'm faced with binding the top, I think it's time I consulted the hive mind before possibly wasting a lot of the remaining binding on experiments.

What are the best ways of making plastic binding more pliable? Bend them as if they were wood, on a bending iron? Heat them at low temperatures, say in a very slow oven? Has anybody figured out a safe, consistent way to do this?

I don't have a fancy side-bending heater, nor do I even have a mold for this particular guitar, since it came partially assembled. And it occurs to me that the problem may be the age of the binding... it had been sitting in a storage locker in the summer sun for years, and might have hardened.

[Diane Kauffmds]

You shouldn't have to prebend plastic. It helps to put it on the guitar, without gluing, before actually installing it. Just tape it in place like you're installing it; it'll shape it. But if you feel it's too stiff, use a hairdryer as you're putting it on. Be careful. Don't overheat it.

I have to use plastic when I restore some guitars. It's always been pliable enough to easily install. I ran into some black plastic that was stiffer. I've never had a piece break. I'm sure you'll be okay.

[JLT]

Thanks, Diane.

This plastic is a LOT stiffer than just about anything else I've come across. I'll do some experimenting with it, to see if it really wants to go around that cutaway without giving me grief, and let you all know what I come up with.

[tippie53]

that is too thick and should be sanded to .065 if you need to bend it seriously boil some water and stick the cutaway end into it. let heat a few min then tape to the cutaway area and let cool A hair dryer may also work

[JLT]

Well, I did some experimenting this morning. I tried three methods:

1. Taped the binding onto the guitar and then heated it with a hair drier. I couldn't get the temperature higher than about 120* F and, when I removed the tape, the plastic returned mostly to its former state, although it did bend slightly. (All temperatures were taken via one of those laser thermometers.)

2. Put it into a slow oven at around 200* F (actually a solar oven). When I took it out, it was very flexible but when I taped it and let it cool, the bends straightened.... not as much as the first method, but enough to discard that idea.

3. Heated my bending iron to about 170* and bent the binding just as if I were bending wood, but without using water. The binding bent like a charm and, when it cooled, it stayed in that shape.

That was the end of the experiment, and since it had reached 90* in the shop, I called it a day.

[Bob Gleason]

Plastic changes with time. Pickguards curl, and binding stiffens and shrinks. I save all my plastic for those oddball repairs that might come along, even though I no longer do repairs if I can weasle out of them. For curves, old binding has not worked well for me. Old plastic binding is not worth messing with IMO.

[JLT]

Plastic changes with time. Pickguards curl, and binding stiffens and shrinks. I save all my plastic for those oddball repairs that might come along, even though I no longer do repairs if I can weasle out of them. For curves, old binding has not worked well for me. Old plastic binding is not worth messing with IMO.

Thanks for the info, Bob. My theory, if you want to call it that, is that the fifteen years the binding spent in that storage shed has "cured" it enough that most of that bad behavior will be in its past. I'm curious to see how it will be on the guitar, and since I'll be keeping it for a while to use as a "jam" guitar, I'll have the chance to see if the theory is correct.

And, if it fails down the line, I can always replace it with wood bindings. I've done that before.

[BlindBo]

Hey JLT. I was thinking the same thing John said. I’ve never used plastic binding over the stock 0.06”+/- thickness. 0.08 is 33% thicker and I’m not surprised it’s stiffer. I use some 0.08 wood purflings and they’re a bear to shape.
As opposed to Diane, I always try to pre shape my bindings (0.06”) by repeatedly running them thru my thumb and index finger to do some “thermal bendiing”. I find it easier to work with when I pre shape it if I’m doing a multi strand purfling/binding. Sounds like you got it solved.

[JLT]

Well, the binding is on and it seems to be working well. I used the bender to get as close to the contour of the bouts as I could, and have relied on glue to get the rest of the work done.

[JLT]

I spoke a little too soon...

After I started applying lacquer to the body of the guitar, I noticed a wee bit of buckling on part of the binding, causing it to lift out of its groove about 1/16" of an inch. I don't know if the lacquer softened the Duco cement that I had glued the binding on.

So I shot some CA glue into the gap and clamped it down real good. The next morning, the binding was staying in place without the clamp, so I resumed finishing the guitar. There's about seven coats of lacquer right now, and there's been no further issues with the binding. Two more layers and I'm done with it until the lacquer cures.