Technique lab

Slide guitar

Same physics as harmonics, with a tube instead of a fingertip. You do not press the string to the fret. You stop the string in the air, exactly over the fretwire.

Three rules

Sit over the fretwire, not behind it. Behind the fret is how you finger a note. Over the fret is how you intonate a slide note.
Touch, don’t mash. Clack or thud means you pushed the string onto the fret.
Keep the tube parallel to the frets. Tilt and each string is a different pitch.

Vibrato is a small left-right rock on the target fret, not a big smear.

Setup

Action a bit higher than a shred setup — enough air that the tube does not slap frets.
Strings: .011+ electric; acoustic often .012–.013. Light nines collapse under brass.
Don’t rebuild the guitar on day one. Heavier strings first.

Material	Feel	Voice
Glass	Light, slick	Warm, smooth
Ceramic	Medium	In between
Steel	Smooth, firm	Bright, cutting
Brass	Heavy	Grit, sustain

Beginner pick: medium glass or light steel on the pinky or ring. Index-finger slide leaves nothing behind the tube to mute.

Muting

Fingers 1–2 rest behind the slide (nut side) and kill leftover rattle. Picking hand mutes strings you are not playing. Slide on six ringing strings at once is a choir whether you asked for one or not.

Standard vs open

Standard is good for single-string lines. A six-string barre is not a real chord because of the B-string major-third break. Open G or Open D makes a full-bar chord sing.

Open G barre map     Open D barre map
fret 0   G           fret 0   D
fret 2   A           fret 2   E
fret 5   C           fret 5   G
fret 7   D           fret 7   A
fret 9   E           fret 9   B
fret 12  G           fret 12  D

Five drills

One string, three frets. High E or B. Slide over 12, hold, slight vibrato. Then 7, then 5. Mute behind the tube.
Intonation test. Play the 12th-fret harmonic, then slide to 12. They should match.
Incoming slide. Start a fret below the target, arrive on the wire, stop.
Open-tuning bar. Open G or D. Barre 0, 5, 7, 12 — I–IV–V–I.
Two-string line. Slide only strings 1–2. Mute 3–6 with the picking palm.

Don’t press until it frets. Don’t wear the slide on the index and wonder why it howls. Don’t learn 40 licks before you can hit fret 12 in tune.

Printable one-liner: Slide sits on the fret, not behind it. Mute behind the tube. Open G or Open D if you want a barre to be a chord.