Inlays on guitar or similar fretted instrument are visual elements set into the exterior wood. Typically, inlays are located on the fretboard, headstock, around the soundhole and on the pickguard. Inlays range from simple plastic dots on the fretboard to fantastic works of art covering the entire exterior surface of a guitar (front and back).
Fretboard inlays are used not only as decorations, but also as the markers to determine particular frets on fretboard. They are most commonly shaped like dots (circles), diamond shapes, parallelograms, isosceles trapezoids, shark fins or large blocks in between the frets. Dots are usually considered the easiest to make (and thus, somewhat less expensive), as making a dot only requires drilling a round hole and glueing a pre-cut piece of inlay material into it. Traditionally, major manufacturers have their own preferences in inlay designs and use them on overwhelming majorities of their guitar series: Fender uses dots, Gibson uses isosceles trapezoids — it's also a characteristic of rivalry between Fender and Gibson. Some manufacturers go beyond these simple shapes and use more creative designs such as lightning bolts or letters and numbers.
Smaller dots are also usually inlaid into the upper edge of the fretboard in the same positions, small enough to be visible only to the player. The simpler inlays are often done in plastic on guitars of recent vintage, but many older, and newer, high-end instruments have inlays made of mother of pearl, abalone, ivory, colored wood or any number of exotic materials. On some low-end guitars, they are just painted. Most high-end classical guitars have no inlays at all since a well trained player is traditionally expected to know his or her way around the instrument, however players will sometimes make indicators with a marker pen, correction fluid, or a small piece of tape. Fretless guitars may or may not have inlays that mark frets and intonation.
Another high-end solution involves putting LEDs or optical fiber in the fretboard and make inlays illuminate. This is becoming increasingly popular among the rock musicians that play gigs at dark venues with constantly changing stage lighting, as it allows them to clearly see the fretboard under any conditions.
On guitars, there are two popular fretboard inlay schemes:
Beyond the fretboard inlay, the headstock and sound hole are also commonly inlaid. The manufacturer's logo is commonly inlaid into the headstock and pickguard, if present. Sometimes a small design such as a bird or other character or an abstract shape also accompanies the logo. The sound hole designs found on acoustic guitars vary from simple concentric circles to delicate fretwork. Many high-end guitars have more elaborate decorative inlay schemes. Often the edges of the guitar around the neck and body and down the middle of the back are inlaid. The fretboard commonly has a large inlay running across several frets or the entire length of the fretboard, such as a long vine creeping across the fretboard. Most acoustic guitars have an inlay that borders the sides of the fretboard.
Some electric guitars (like the Fender Telecaster and Stratocaster) have a dark wood inlay – contrasting to the light colored maple – running on the back of the neck, commonly referred to as a "skunk stripe". Strictly speaking it serves a structural function, unlike merely decorative inlay, because it covers a cavity for the truss rod that runs the length of the neck. With one-piece maple necks the truss rod is fitted from the rear of the neck, as opposed to being fitted from the front where it is covered by a separate fingerboard. Even though some makers fit the truss rod from the front of the neck and do not require a "skunk stripe" on the rear, they emulate this appearance by inlaying a purely cosmetic "skunk stripe".
Some very limited edition high-end or custom-made guitars have artistic inlay designs that span the entire front (or even the back) of the guitar. These designs use a variety of different materials and are created using techniques borrowed from furniture making. While these designs are often just very elaborate decorations, they are sometimes works of art that even depict a particular theme or a scene. Although these guitars are often constructed from the most exclusive materials, they are generally considered to be collector's items and not intended to be played. Large guitar manufacturers often issue these guitars to celebrate a significant historical milestone.
Solid-body electric guitar's body inlaying is somewhat more common (as there's a plenty of wood to carve them down), but acoustic guitar's bodies and sound holes are occasionally also get inlaid. It is generally considered to be much more delicate work, as:
This is the decorative edge found around the body and/or fretboard of an acoustic or electric guitar. Its purpose is not merely decorative, however. Because of the construction methods, the edges of the body are typically the weakest point of the acoustic guitar. There is not much wood there, as the sides have to be thin to allow for bending, and the top and back have to be thin to allow the string vibrations to resonate. Trying to connect two thin pieces of wood at a 90 degree angle is an engineering challenge, so the binding is the usual solution to strengthen the construction. The corners are overbuilt, using a lining. Linings are usually made of mahogany or basswood, and are either solid or kerfed:
The purpose of lining is to increase the surface area for gluing the top, back and sides together. When the top, back and sides are all glued together, this is called the box. The edges of the box, where the top and sides, and the back and sides meet, now have a ledge cut out, for the binding to be glued into. The bindings primary importance is to prevent moisture seeping into the endgrain and causing checking, or small splits in the end of the wood, caused by changes in humidity. Most common materials used for binding are plastic, but any hardwood can be used, or any number of other materials. Popular on most instruments is laminated binding, where multiple layers of different coloured plastics are glued together to pleasing effect. White-black-white is seen most often.
Purflings, on the other hand, are purely decorative, and serve no important purpose like bindings. There is an additional, shallow ledge cut out, either butting up against, or fairly close to the bindings, on the top or back, which is then filled in a similar manner to the bindings. However, instead of solid materials, often patterned material is used, made up of different colour or dyed hardwoods, often in patterns such as herringbone or houndstooth. Also popular is abalone purflings, as popularized by the acoustic guitars of C. F. Martin & Company.