One harmonic technique you can use on the guitar involves using a pick. A pinch harmonic is one where you hold a pick very closely to its picking edge, so close that your finger and thumb rub against the string as you pluck it. Essentially, you pluck and graze the string at the very same time, producing a combination of a primary note and artificial harmonic. This all happens in the area between the neck and the bridge where you normally pick.
This technique takes some getting used to — you need to not graze so much that it cuts off the string, or too little that no harmonic is produced. Experiment with your pick placement between the neck and bridge to find a node that will produce a harmonic. Perhaps most important, this technique works best on an electric guitar with a lot of distortion and volume.
In the example below, whole-step bends are played at the seventh fret of the third string, the kind typically used in A-minor pentatonic. You can tell when to use a pinch harmonic because “P.H.” is printed above the tab line and the standard notation features diamond note heads.
As you watch this video of pinch harmonics, notice how, in the first measure, the bends are picked normally. In the second measure, the strings are grazed with the tips of the thumb and finger, and the fingers are slowly moved from a center position between the neck and bridge toward the neck, exciting different harmonics along the way. The bending is then discontinued and a phrase is played in the A-minor pentatonic, using pinch harmonics through to the end.
Pinching the pick and playing harmonics like this produces squeals and squawks that are common to hard rock and heavy metal music. One of the better examples of using pinch harmonics is ZZ Top’s “La Grange,” specifically the second solo beginning around 2:30.
You hear something very similar in Van Halen’s “Outta Love Again” at the 1:06 mark (along with just about every other Van Halen song). The more distortion is used, the greater the harmonics scream. For some of the “wildest” examples, check out anything by Zakk Wylde, like “Miracle Man” and “No More Tears,” which he recorded with Ozzy Osbourne. Pantera’s “Cemetery Gates” opens with a hard and heavy pinch harmonic filled riff.