Hawaiian slack key guitar (kī hōʻalu) is a truly unique and special acoustic guitar tradition. Kī hōʻalu, which literally means “loosen the key”, is the Hawaiian name for the solo style chosen, exclusive to Hawaii. In this tradition, the strings (or “keys”) are “loose” to produce many different tunings, usually containing a major chord or a chord with a seventh major note or sometimes one with a sixth note. Each tuning produces a persistent sound behind the melody and has characteristic resonance and fingering.
Slack key legend Cyril Pahinui says that when he met and played with Chet Atkins in Nashville, Tennessee, Atkins told him that the tunings he used in slack were what Atkins considered open tunings. The knowledge and popularity of the slack key guitar further increased with the release of several great slack key albums in the 1960s by Leonard Kwan, Ray Kāne, Atta Isaacs and Gabby Pahinui on Margaret Williams' Tradewinds label. At age 13, after two years of learning Uncle Raymond's nahenahe (sweet sound) style, I met Sonny Chillingworth, another legendary master of Slack Key's art. George Kanahele did a lot to raise awareness through his publications, music classes and concert sponsorship, including the historic 1972 Slack Key concert.
Influential teachers Raymond Kane and Sonny Chillingworth, who worked hard to teach and transmit the art of Hawaiian Slack Key to the next generation, were very strict about it. To this day, every key Slack artist draws on the traditions of the area in which they grew up and the music of their ʻohana (family), adding to it their own individual way of playing. It's like having a mini symphony at your fingertips. It's a way of tuning (or adjusting) the strings to a chord so that the musician doesn't have to use an entire hand just to hold a chord.
This frees up the hand that moves with the fret, while the hand that touches the pointer establishes an alternating bass pattern on which a false rhythm and main melody are played. Essentially, it's the art of simulating multiple instruments simultaneously on a single guitar. The Hawaiian Slack Key guitar is a rare art form; among the traditional Hawaiian arts, it ranks as one of the least known and least practiced. It expanded the limits of the loose-key guitar, turning it into a fully evolved solo guitar style, capable of creatively interpreting a wide variety of traditional and popular Hawaiian standards, original guitar parts, and even pieces from other countries.
These trends are deeply rooted in the weak-toned guitar, as an accompaniment to vocals, as instrumental compositions or as interpretations of vocal pieces. The band Gabby Pahinui from the 1970s is a good example of the complexity of the sound that Slack Key can achieve. There's a mystique surrounding loose-key guitar music: it's very personal and can have a very magical feel to it. More loose-key guitar recordings are now available in Hawaii, on the mainland and other countries, and several guitarists are touring more frequently outside of Hawaii.
Pahinui learned directly from his father, Gabby Pahinui, whom many consider to be one of the creators of Slack Key. As a child growing up in O'ahu, I had the immense fortune to learn from some of the leading practitioners of the Hawaiian slackkey guitar. The loose tradition received an important boost during the reign of King David Kalākaua, responsible for the Hawaiian cultural revival of the 1880s and 1890s. Almost all loose keys require retuning the guitar strings relative to the standard ones (EADGBE), and this usually (but not always) means lowering or loosening several strings.
It's a colloquial phrase that basically means playing with open tunings.