Palm Muting: How to Mute Strings with Your Picking Hand
Palm muting - resting the edge of the picking hand near the bridge to slightly deaden the strings - is the same principle as muted strumming (see [[percussive-muted-strumming:the article on muted strumming]]), just applied to single notes and riffs on electric guitar instead of chord strums.
Where the "chugging" tone comes from
The edge of the hand (the pinky side) rests on the strings right at the bridge, a split second before the pick strike - just enough contact that the string doesn't ring open, while the note still sounds, only shorter and duller. That muted, chugging tone is exactly what's recognized in riffs across most rock and metal songs.
Why it's more noticeable on electric than acoustic
Distortion (see the article on starting electric guitar) amplifies any string noise, intentional or not - so on a distorted electric tone the difference between a muted and an open note reads far more sharply than on a clean acoustic sound. That's exactly why palm muting is practically a required skill on electric, not an optional flourish.
Finding the right amount of pressure
Too much palm pressure kills the string's sound entirely, leaving a dull thud with no pitch. Too little and the string rings almost open, with no audible mute. The right amount sits in between: the note is still recognizable by pitch, but noticeably shorter and duller than open.
Drill on one note, then a riff
Start on a single open bass string: play it in even eighth notes to a metronome, keeping the palm in the same spot near the bridge - the goal is a consistently muted tone on every hit. Only once that single tone is stable should you carry the technique over to a simple riff or a power chord (see the article on power chords).
Palm position decides everything
Shifting the palm slightly toward the neck gives a duller, more thudding tone with less pitch. Shifting it closer to the bridge leaves more ring and mutes less. Experiment with the palm's position by a couple of millimeters in each direction until the tone matches what a specific riff actually needs.
Try it in practice
Open chord trainer