Ask the Expert: All About Celluloid Rot—and What to Do About It

Q: I just inherited a beautiful vintage Gretsch acoustic from my uncle. It’s in great shape and spent most of its life stored in the case, but some parts of the binding look awful. There are lots of tiny cracks, like it’s crumbling to pieces. What is this, and can it be repaired? —Lev G., via email

A: Congratulations on the new (old) guitar! Your Gretsch is showing signs of what is commonly known in vintage guitar circles as celluloid rot. Essentially, this means that the plastic used for the binding is degrading. This is not due to any mistakes in handling, storing, or cleaning the guitar—the problem comes from the composition of the material itself. Let’s take a quick look at its history and chemical properties, and why this deterioration seems to happen.

Celluloid is one of the earliest plastics. Chemically similar predecessors emerged in the late 1860s, and by 1870 the material was on the market as “Celluloid.” As the name suggests, the primary base material is cellulose, a plant compound that is also the basic building block of everything from paper to clothing. The addition of nitric acid creates a material we all know by name—nitrocellulose—which has become legendary as the lacquer of choice for nearly every beloved vintage guitar brand. Celluloid was also used to develop the substrates for camera film and served an important role as a substitute for elephant ivory in products ranging from billiard balls to hairbrush handles.

In order to make a workable and flexible material, manufacturers added plasticizers to this formula, and the result was the very factory-friendly plastic binding that we know and love. It flexed and conformed easily to the curves on the guitar, glued quickly and easily with a range of adhesives, scraped and sanded well, looked beautiful, and bonded perfectly to lacquer. However, these plasticizers slowly migrate out of the plastic. To put it more simply, they vaporize and leave behind a shrunken and brittle result. This can happen relatively quickly in some cases—one of the worst I’ve ever witnessed was a guitar from the early 1980s.

Unfortunately, although the chemistry that causes celluloid rot is relatively well understood, the circumstantial factors that may affect it are still the subject of some speculation, even among repair and restoration professionals. Since the main culprit is the release of gases from the plastic, many believe that the rot can spread and contaminate other nearby guitars. Collectors of other vintage celluloid products—particularly straight razors and fountain pens—seem to widely subscribe to this theory. Others insist that storing the guitar inside a case will accelerate the problem, as the gases are trapped inside the case and not allowed to dissipate into the surrounding air. There is anecdotal evidence on both sides, but not any really conclusive proof for either case. 

Part of the reason for this speculation is that there seems to have been considerable inconsistency in celluloid manufacturing from batch to batch. East Coast guitar makers like Guild, Gretsch, and D’Angelico were likely purchasing from the same supplier, and thus those brands seem to represent a large percentage of cases of rot. (Gretsch is by far the most common that I’ve encountered.)

However, variables such as the type and quantity of adhesive used to glue the binding seem to be implicated, and these can vary from guitar to guitar, even within a particular brand. As a result, the problem is not always easy to predict by make or era.

One other potential culprit that has been identified is refinishing. Thanks to the chemical similarities between celluloid binding and nitrocellulose lacquer, some repair techs have suggested that refinishing a vintage guitar can potentially initiate binding rot, since the solvents in the lacquer will penetrate and soften the binding, making the molecular structure less stable.

Beyond the obvious cosmetic issues, celluloid rot can present other problems. The gases that escape from the plastic will attack the integrity of protein-based adhesives such as hide glue, which means that glue joints adjacent to the binding can open up or lose strength. Unfortunately, the longest glue joints on a guitar—those between the rim and the top or back—are directly in contact with the binding, so your luthier should always make sure to test or evaluate those joints prior to any repair. I’ve also seen cases where celluloid gases from fretboard binding will quite severely blacken nearby metals, such as the ends of frets.

Fortunately, for such a complicated problem, when it comes to repair, the course is clear: rotting binding needs to be removed and replaced. I have myself been tempted to try to fill and stabilize some lightly cracked celluloid in the past, but that is a short-term solution at best. And, as mentioned above, the solvents involved in doing touch-up work can make the situation worse.

Removal of rotted celluloid is fussy. Despite its chalky, powdery texture, it can take careful and precise work to cut it away without damaging the surrounding wood and finish. It has a potent odor and is highly flammable—I’ve even heard reports that it can self-ignite under certain conditions—so care is recommended at every level. Once degraded celluloid is removed, the guitar’s binding ledges have to be cleaned, taking care not to leave behind any little seeds of old rotted plastic that could potentially contaminate the replacement binding. It’s pretty common for people to save the little bits of binding or pickguard that fall off their guitars. If you do so, please handle and store them with caution. Or better yet, just dispose of these bits; there’s really no use for them.

Matching the aged, amber-tinted lacquer on antique binding is a real art, and I’ve seen some unfortunate examples of nicely replaced binding that was poorly touched up and looked terribly out of place. I always recommend taking good photographs of the old binding prior to replacement to serve as a reference point for color during touchup. We are trying to preserve these old instruments, and it is important to keep them looking correct.

The biggest question when restoring celluloid binding is whether to use celluloid for the replacement or substitute a different plastic that won’t potentially suffer the same fate. Newer formulations of celluloid are most likely manufactured with much better consistency and control than was possible in the 1930s and ’40s. However, if the choice is made to put new celluloid on an instrument, it’s important to keep in mind that it is not guaranteed to be immune to rot in the future.

Given the cost and labor involved with replacing rotten binding, many players choose to just live with it, or lightly tack-glue it in place to minimize losing the loose pieces. If you decide to leave it be, it’s best to play it safe and not put it on the rack right next to your three D’Angelicos. When the time comes to finally replace the rotted binding, I’d recommend shopping around to find a luthier with some experience and understanding of the specifics of this problem—it could make a big difference in the quality of the result.

Martin Keith is a luthier, repair and restoration expert, and working musician based in Woodstock, New York. martinkeithguitars.com 

This article originally appeared in the March/April 2020 issue of Acoustic Guitar magazine.