There are at least a couple of historical threads that led to the phenomenon of slide guitar as we know it now. One was the African-American instrument called the Didley Bow. These were homemade, one-stringed instruments played with the right hand plucking a wire & the left hand sliding a glass or metal object along the wire to change the pitch. Slide guitar also developed, apparently independently, in Hawaii too, as the lap steel guitar (check out our friend & Musical Questions participant Scott Houston here— Scott’s a lap steel player). Tho the lap steel itself isn’t a really common blues instrument, it’s important to blues history because the Hawaiian music fad of the early 20th century had a big effect on all forms of U.S. popular music. When W.C. Handy, composer of “St Louis Blues” first heard a slide guitarist at the Tutwiler, MS train station in 1903, he described it as follows:
A lean loose-jointed Negro had commenced plunking a guitar beside me while I slept... As he played, he pressed a knife on the strings of the guitar in a manner popularized by Hawaiian guitarists who used steel bars....The singer repeated the line three times, accompanying himself on the guitar with the weirdest music I had ever heard.
Slides originally were pretty much any handy glass or metal object (because of those materials’ resonant capacities); bone was also used. When glass was used, it typically was the cut off neck of a bottle—hence the term bottleneck slide. In the videos below, no one is playing with a true bottleneck, but Mississippi Fred McDowell is playing with a glass slide. A variation on this is a glass medicine bottle, such as the glass Coricidin bottle used by Duane Allman. Coricidin isn’t available any longer, but replicas are made, & of course, you can buy pre-made glass slides too. Other objects that were commonly used were jackknifes (see the Mance Lipscomb video); pieces of copper tubing (Son House) & socket wrenches (see Rory Block).
The slide doesn’t “fret” the strings in the way that a finger would; it glides over the top of them, & the frets are really superfluous except as position markers. Tho some people play slide style with the guitar in standard tuning, it’s much more common to play with the guitar tuned to an open chord, usually either D major or G major. For non-guitarists there, that means that if you strum all 6 strings with no string being fretted, a major chord will sound—thus as the slide moves up the neck you move from one major chord to another (in standard tuning, the 6 unfretted strings don’t play a common chord). This is handy because it means that the player doesn’t need to use any left hand fingers, & in some styles, it would be virtually impossible to do so—Bukka White, you’ll notice slides the long nail he’s using across all 6-strings constantly, while Mance Lipscomb also never frets any strings in playing his “knife blues.” Mississippi Fred McDowell, Son House & Rory Block, on the other hand, fret a number of notes while playing. All three of these players wear the slide on the ring finger, which leaves the index, middle & (theoretically at least) little fingers available for fretting; some players prefer wearing the slide on the pinky & having the index, middle & ring fingers free to fret strings. Conventional wisdom holds that it’s easier to control the slide when it’s worn on the ring finger, however.
Hope you enjoyed this overview. Now for the real thing: some music from five great slide players! & if you want a bit more slide guitar, check out my post on Ramblin’ Thomas’ version of “Poor Boy Long Ways from Home” (really a completely different song than Bukka White’s) on Just a Song.