While cleaning out my email, I found some tips on slide playing that I sent to one of my son Ethan’s friends. It occurred to me that they might be useful to others too, so here they are.

Playing slide well is a combination of three things: being able to hear the note and how close you are to it, the muscle memory to get close to the note without hearing it, and the ability to adjust when you miss.

Remember that NOBODY on an unfretted instrument plays totally in tune all the time. Not Heifetz. Not Casals. Nobody. The trick is to develop good muscle memory and quick ears so that you adjust quickly enough so that the listener can’t hear when you miss.

I find that slide is best played with fingers (either with finger picks or bare fingers) rather than a flat pick, as you can use the fingers to damp the unused strings. Start with resting the little finger on the high E, the ring on the B, and so on. The thumb covers the low A and E. Dedicate a right hand finger to each string, and damp with the fingers that aren’t in use. It takes a while to get the hang of this but you will have very clean results. If you need to play fast quickly before you master this, alternate your thumb and first finger, using your palm to damp.

I put the slide on my little finger so as to be able to fret with the others. You may find that you have more control with your ring finger. Bonnie Raitt uses her middle finger. Try them all and see what works for you.

It’s a good idea to have a guitar set up for slide if you own more than one. That way you can raise the strings enough so the slide doesn’t rattle or fret out. I also recommend at least an .012 set for slide, and you should consider a wound third and heavier strings.

Tunings for slide are a whole other world, but apart from standard tuning you should experiment with at least open D (DADF#AD, low to high) and open G (DGDGBD, low to high). It’s a gross oversimplification, but open D sounds like Elmore James or Duane Allman and open G sounds like Keith Richards or Robert Johnson. The big difference is that in open G the third is on the top two strings while in open D the third is between the fourth and the third. In standard tuning the third is between the third and second string, so learning an open tuning means that the chord forms you know either don’t work, or produce a chord you don’t expect. It didn’t take me that long to find most of them in open tuning though.

Here are a bunch of slide exercises for any tuning.

Hit an open string, for example the low E, and let it ring. Then slowly slide up or down to an E on any other string and listen to the beat frequencies as you bring the note in tune with the open string. Take your time and try to relax your left arm.

Then do the same thing with fifths, fourths, thirds, etc. Spend a lot of time with each interval, hearing what it sounds like against an open string. Check your work often by fretting a note, then sliding to it.

If you have a good tuner, play plugged into the tuner, and observe what happens as you gradually bring the note in tune. Then go to another note without looking at the tuner and see how far off you are.

Then try the same thing in different keys, moving the drone chromatically up the neck. A loop or delay pedal is good for this. You can loop your drone note in any key and play all the intervals against it.

Then try going for specific intervals starting from each note of the chromatic scale. (Do each of these exercises on one string. If you can do it on one string, it translates to all.) Start on, say, F. Then hit an F an octave higher and go back down, both sounding the slide between the notes and muting it. Then go from F to E. Then F to Eb, etc. Then reverse the process.

Do NOT do these exercises fast. Do them slowly and listen and correct yourself. Train yourself not to get angry when you miss, but adjust.

After you’re sick of this stuff, play a simple tune with a diatonic melody. I like “Amazing Grace” or “Silent Night.” But pick one you really like, because you are going to play it OVER and OVER again until it glistens. Play it on one string first. Then two, then on however many strings you like. Play it in every register on the guitar, starting on every string.

Now experiment with the articulation. Play every note separately, as if they were fretted. You want to be able to simulate fretted playing with the slide, as the contrast will be much more effective when you start adding the articulations. Then start connecting the notes, sliding into them from above and below, and so on. Play the tune very slowly and LISTEN to the effect of the glissandos.

Once you can nail diatonic tunes, work on a standard such as “All The Things You Are” that has a simple melody and moves through a number of keys.

If you like blues or country slide, experiment with sliding up to just under the third, fifth, and flat seventh. Slide is about the infinite number of pitches between two points on a string. (So is string bending.) Try to find as many of them as you can, and observe how they make you feel emotionally.

Once you can play a standard in tune, start copying female singers note for note, inflection for inflection. Try to match their vibrato. How fast is it? How wide is it? Does it start at the beginning of the note or come in after the pitch is established? Slowing this stuff down can be really instructive.

Dionne Warwick is a good one to start with; classic phrasing, great pitch and time, without a lot of extraneous flash. But pick one or two you really like. The more melismatic singers like Patti LaBelle or Aretha are for more advanced study if you want to go down this path. I spent two weeks with an Aretha Franklin greatest hits tape once and it was one of the best things I ever did. You should do this with your regular string bending also.

Remember that tempered tuning is not the same as the intervals generated from the overtone series of a vibrating string. Learn to hear both, so that you can play “in tune” with a keyboard or a tuner, or “in tune” with your vibrating strings and harmonics. Thirds in particular are slightly different in each case.

To develop your vibrato, start slow, with quarter notes on the metronome. Move up and down equally distant from the center pitch. Then systematically speed it up a few beats at a time. Like delay, vibrato is very effective if it has a rhythmic relationship to the beat. Don’t be wedded to this concept but be aware of what you can do with it.

Once you have all this together, if you want a real challenge, you can start learning things like bebop heads or Bach cello suites on slide. Hours and hours of family fun! But no matter how far you get, do basic intonation work (intervals sounding against a reference pitch) at least fifteen minutes a day. In my experience, intonation, vibrato, and sight reading are the musical skills that deteriorate fastest if you don’t practice them consistently.

This should keep you busy for a while!