Slides - What they are and how they work
A
slide operates somewhat like a moving fret, altering the vibrating
length of the string and therefore changing the pitch. A slide can be
almost any fairly hard, smooth object held against the strings by the
fretting hand. Early country blues players are said to have used steel
knives, probably fairly heavy work knives. The knife handle would have
been held in the hand with the thick, blunt back of the knife against
the strings. However the favourite weapon of choice was the broken off
neck of a wine or beer bottle, slipped over one of the fingers of the
fretting hand.
Like so many
things today, modern glass bottles often don't resemble the sturdy
glass bottles being made in the 1920's when the slide style was born.
The musicians of the time were just being practical and using what came
to hand that seemed to do the job, but it turns out that the old
bottles were almost perfect for slide playing. The hard heavy glass had
plenty of inertia and Its internal acoustic damping factor was low,
so notes would sustain well. The glass surface moved easily over the
strings and did not wear. The outer curvature was just right to serve
as a witness point for one end of the strings and the inner diameter
was right for the finger.
Many cheap
glass slides made today are too light and soft and don't have a bottle
neck's natural flare, which allows for playing inside slide notes with
the outside strings open. The extra weight at the top of a bottle neck
slide due to the flare also helps develop a smooth vibrato.
Some
people
prefer brass or steel slides and Lowell George, the slide guitarist with
Little Feat, used a steel socket wrench. Most metal
slides don't have the bottle necks organic shape and have parallel
sides.
There has been a recent vogue for ceramic slides and these can offer a slightly different tone to glass or metal.
For lap style
playing as distinct from bottle neck slide, a solid slide is used.
These are either in the form of a bullet slide - a 17 to 20 mm round
bar about 80mm long with one domed end - or a 'Stevens bar' a solid
metal bar that looks a little like a piece of miniature railroad track,
also about 80mm long. The bullet slides can be made of metal - often
plated steel - glass, or even plastic.
Which Finger?
For
the slide
beginner there is always the question of which finger to use for
the slide, and this does affect choosing the right slide since
the inner diameter that's right for the small finger will be too small
for, say the ring finger. There isn't really a right or wrong choice of
finger, but using the small finger does mean it is relatively easy to
slide up over the body, particularly on a 12 fret to the body neck.
Using
the
other fingers frees up fingers in front of the slide for fingering
fretted notes and the slide is arguably in a more secure positon
between the fingers. However the little finger does seem to be the most
common choice and if the player chooses to both fret and slide (most
do) using one of the other fingers for he slide does mean that the
playing technique varies a little, depending on which finger is chosen.
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