When playing slide guitar, different materials used on your strings will create slightly different tones. If you are after a smooth slide with long, clean sustain, you should try a cut-off bottleneck, which was Ry Cooder’s choice. If you are aiming at something less atmospheric and with more “bite,” go for the classic metal slide. A non-round surface like a blade can bring out a more “grating” sound by slightly scraping the thicker strings, while plastic round containers will create a more dull sound. Bone slides tame the bright overtones for a moodier tone. Heavy brass slides work better on the acoustic guitar’s “harder” strings, while the softer strings of the electric will require a gentler action and lighter slide. Assuming that you know that when playing in this style you don’t have to press the strings down to touch the neck, bear also in mind that damping the strings behind the slide with the free fingers on your left hand will give you a cleaner tone without too many ringing notes.