Kenneth Michael Guitars est.1978

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KMG "Success Kit" Installing bindings

Generally speaking plastic bindings and purflings are a bit easier to install than wood because they are more flexible. However, the process with the exception of the adhesive used, is very similar. The binding channel for the top and back are normally the same set-up, so the shallow, wider rebate for the purfling is usually routed last to avoid double set-up time.

While visiting the C.F. Martin factory I observed the binding techs carefully double and triple checking the depths of all the binding and purfling channels. Even though at their disposal was the most advanced routing equipment, this quality check was unfailingly performed. Irregularities in the channels were leveled with sand paper and files to make the rebates as precise as possible.  Make no mistake this procedure is mandatory if we hope to achieve professional results relative to binding and purfling installation.

When filing and or sanding to clean up the channels take care not to round over the edges, if the intersections are not flat and square, gaps will result.

As with all guitar construction operations, an organized work place is very important. Also, being able to hold the guitar in a stationary position is helpful during different stages of the installation process. Note the abundance of pre-cut masking tape in the picture – having this ready in advance speeds and simplifies the operation. I like the green 3M masking tape available at auto parts stores.

Small sticks and/or brushes can be used to apply the glue to the channels and the binding/purflings. Keep the coverage as even as possible. Work in 6-8 inch sections, as you apply the glue a portion the previous 8” section will no doubt break loose. For this reason it is mandatory that you re-check and re-tape your work while progressing around the rim. The bindings/purflings must be securely glued to the top or back plate. The alternative is, at best, a not so attractive repair especially when the light top wood is involved.

Because there is a butt joint in the binding visible under the neck heel my preference is to tape the binding "without glue" all the way around the guitar. This way I can cut the binding to length and make a perfect joint. I then remove the tape apply the glue and tape the binding in place.

The ends of the top trim fall under the fingerboard, so the installation can begin at the neck mortise slot and continue around the perimeter then trimmed at the end. It’s not mandatory, but a practice run with the multiple strips of binding and purfling is a very good idea. This affords a chance to uncoil the material and get a feel as to how the layers will line up before any glue is applied. The stack up of material causes a lot more resistance than the binding alone – extra vigilance is needed checking for gaps, spring back can even occur under the tape. So check and re-check.

The adhesive that we use for the plastic bindings contains a very strong solvent; consequently it tends to soften the binding and purfling material. Because perfect seams are so important I recommend that the binding installation be allowed to dry over night. The tape should be removed very carefully pulling it back at an angle to the grain. Usually with the green 3M masking tape removal goes without any problem. If there is too much resistance and splinters are coming off with the tape, a hair drier set on low heat should be used to warm the tape to aide in the removal process.

Sand paper is not a good choice for leveling plastic bindings, grit lower than 220 tends to imbed severe scratches. And sanding with 220 grit would make for some real slow going. When leveling a surface remember to focus on the area around the low spots – in other words all the HIGH area has to be removed and blended. Rubbing on the low spots just make the situation worse and in the end will produce a very visible defect.

Neck Prep and Assembly

I have found that a simple cabinet scraper blade is the tool of choice for leveling bindings
and purfling. When sharpened properly the blade has a razor edge that makes
completion of this process relatively quick. To help avoid damaging the wood surfaces,
round over all the corners of the scraper blade. Always hold the blade at a slight angle;
this results in a shearing action that takes very thin shavings with each pass. At some
points around the rim the bindings may be a bit low to the rim, the cabinet scraper can be
used here to remove wood from the sides as well.