Ask the Expert: Vintage Guitars and Aging Plastic Parts

Hello, gentle readers. Lately, I’ve received lots of questions about issues stemming from aging plastics on old guitars. From curling pickguards to binding rot, it’s one of the things that people have to bear in mind when buying and playing older instruments.

Q: I bought a Martin 0-18 from the ’60s a few years ago, and I love it. It’s a sweet little guitar that’s the right size for me. There are a couple of cracks in the top that I’ve been nervous about getting repaired as they are right next to the pickguard, which is curling up at the edges. There is one under the strings and one at the outside edge. I don’t think it needs much else. Can I safely get these cracks closed up?

—Patty, New York, New York

A: First, I would count myself lucky if the only thing my favorite 60-year-old guitar needed was a little attention to the pickguard and a couple of top cracks! You’re starting ahead of the game.

Here is what’s happening with your 0-18: celluloid is unstable, and as time marches on, it’s bound to degrade. Exposing celluloid to moisture, light, air, and acids causes it to break down. In the case of old pickguards, this usually means shrinkage. The original footprint of the pickguard may start to show around the edge as it shrinks, or the edges may curl up (the technical term for that is “potato chipping”).

Your issue sounds like a classic example of a shrinking Martin pickguard. When the guitar was built, the pickguard was glued to the bare wood and finish was applied over it. As the pickguard shrinks, it pulls the wood along with it, usually causing a crack under the B-string and also sometimes below the waist. Trust me: your repair person has seen this before! To relieve the stress on your guitar’s spruce top, she will carefully remove the pickguard and repair the cracks as much as is possible. Then, she may seal the wood, and depending on how the old guard looks, either re-attach it or replace it with a good copy. There isn’t a lot of guesswork in this repair. Go get a diagnostic from a local luthier!

Got A Question? Uncertain about guitar care and maintenance? The ins-and-outs of guitar building? Or a topic related to your gear? Ask Acoustic Guitar‘s repair expert by sending an email to AG Senior Editor Greg Olwell, greg.olwell@stringletter.com, and he’ll forward it to our expert. If AG selects your question for publication, you’ll receive a complimentary copy of our popular The Acoustic Guitar Owner’s Manual.

Q: I have a 1975 Gibson J-45. The tortoiseshell binding is cracked and flaking off all around the body. In some places, you can see into the soundbox where it has completely chipped off! It still sounds good—it just doesn’t look so good. Can new binding be put on without affecting the playability and value of the guitar too much?

—Fred Green, Katy, Texas

A: Here’s another version of celluloid degradation. In the case of binding, you’re more likely to see the plastic fissure, crackle, and ultimately crumble off. Certain guitars are more prone to it (we see you, Gretsches), and you’ve got one of them. The binding on your guitar is deteriorating, and there’s basically no stopping it, or at least no one has developed a practical way to stop it that’s been put into common use. Once the process starts, it only has one way to go.

“Off-gassing” is another effect of the binding degrading. As the material breaks down, it releases a gas that causes a haze or a halo of darkened wood to appear near the binding (or heel cap, or pickguard) and in some cases is toxic enough to corrode metal hardware. The longer you wait to deal with this problem, the more effects of off-gassing you might expect to see. You say the guitar still sounds good, and if you like it and would like to play it once it’s healthy, it’s worth getting the repair done. If you are interested in selling it, a very usable vintage guitar like a ’70s J-45 with a neatly done repair will get you farther than a guitar with an attached future repair bill for the new owner. 

You may have to do some sleuthing to find the right shop, since not everyone will want—or be able—to deal with the smelly chemical off-gas when removing the remaining plastic. But once you get it back in your hands with shiny new healthy binding, I’m sure it’ll all feel worth it.

A Note About Celluloid

This early plastic was used to make almost everything. From buttons and jewelry to parts for appliances, celluloid began to be used in place of ivory, a much more rare and expensive material. Before the movie industry switched to acetate in the 1950s, one of its most common uses was film. With celluloid’s near-inevitable degradation, imagine what film archivists are up against! The only sure way to stall the process of decay is by keeping this material very cold. As anyone who’s been in a film vault can tell you: the temperature is freezing! Of course, this is not a very practical solution for older guitars. Not many things are still made from celluloid, but that short list includes table tennis balls and, you guessed it, guitar picks.

This article originally appeared in the August 2017 issue of Acoustic Guitar magazine.