It’s not as if Japanese avant-garde sludge outfit Boris isn’t intentionally saturating the market strictly to capitalize on the trio’s recent elite status among indie scenesters in North America. It’s just that they’re so damned prolific. Still, those who were drawn to the dulcet tones and funereal drones of the near-masterpiece Pink a year ago and found themselves interested in whatever the band was going to release in the future quickly learned that saying you liked Boris was one thing, while being an actual fan required a different level of commitment as a consumer entirely. In fact, in the last 12 months, it’s easy to understand why so many people might be turned off by the sheer volume of Boris’s releases alone.

Since the North American release of Pink last May, we’ve seen such discs as the massive-sounding double CD Dronevil Final (requiring the simultaneous playback of both discs), the Vein EP, limited edition releases The Thing Which Solomon Overlooked 2 and The Thing Which Solomon Overlooked 3, the terrific collaboration with drone masters Sunn O))) called Altar, and Rainbow, a collaboration with Japanese guitar whiz Michio Kurihara. With separate US, UK, and Japan versions, special double-CD releases, and limited edition gatefold double vinyl LPs, Boris completists are forced to fork over exorbitant amounts of cash just to keep up. But the thing about Boris that sets them apart form other insanely prolific acts with insanely obsessive fans is, their many releases are always worth checking out.

Rainbow is certainly no exception. Expanding from a trio to a quartet, one would expect the end result to be massive-sounding, but in fact, this album is one of the most disciplined albums Boris has ever put out. Sure, we get the odd swell of drone waves, sludge riffs, and monstrous rhythm section work, but the threesome of bassist Takeshi, guitarist Wata, and drummer Atsuo serves primarily as a supporting act to Kurihara, whose virtuosic guitar work evokes comparisons to the soulful/ear-melting versatility of Neil Young. In addition to Boris’s holding back just a touch, they’ve come up with some of their best vocal melodies to date, the combination of vocal hooks and searing guitar solos completely side-stepping the more primal feel of Pink.

A perfect example of the band’s restraint with Kurihara at the helm is on the opening track “Rafflesia”, which may be stylistically similar to the more blissed-out moments on Pink, but instead of overpowering us with a My Bloody Valentine-like assault of feedback underneath Takeshi’s soaring lead vocals, the band pulls back on the reins, allowing both Kurihara and Wata to offset more powerful chords with cleaner, trilling notes, creating a more introspective mood instead of just pure aggression. “Shine” delves into even mellower territory, acoustic guitar and Takeshi’s plaintive vocals gorgeously underscored by distant, chiming feedback, the intensity increasing gradually, but never quite hitting the boiling point. “Starship Narrator” has the foursome going space-rock on us, the robust rhythm section of Takeshi and Atsuo enabling Wata and Kurihara to explore more spacious guitar tones while retaining the song’s insistent mood. “My Rain”, meanwhile, is a luminous two minute interlude of interweaving guitar melodies over a backwards-masked percussion track.

On two songs in particular, Boris manages to completely outdo itself. “You laughed Like a Watermark” is the most accessible song they have ever recorded, a seven-minute mellow rocker that turns off the distortion completely in favor of a more classic rock ‘n’ roll sound similar to Crazy Horse, the song propelled to gorgeous, euphoric heights thanks to Kurihara’s blistering, jagged solo runs. “Sweet No. 1”, meanwhile, is reminiscent of the band’s more epic moments, but here, they pull back yet again, retaining their trademark intensity, but allowing Takeshi to provide a brilliantly catchy vocal hook, and Kurihara to absolutely let loose with his best solo work on the record. It’s a testament to Boris’s versatility, as both songs sound completely different from the band’s past work, yet still sound like the Boris that so many people adore.

The only slight disappointment with Drag City’s North American pressing of Rainbow is that the pretty, borderline whimsical “...And I Want”, which concluded the Japanese release, has been replaced by the dour “No Sleep Till I Become Hollow”, which ends the album on a comparatively downbeat note. A minor gripe, though, as the previous eight tracks are worthy enough, proof that not only is Boris one of the more consistently reliable bands in rock today, but for all the side projects and special editions, their ever-expanding back catalog always shows tremendous artistic growth. Who knows what they’ll come up with a couple months from now?