The cover imagery of Paper Airplane, Alison Krauss’ first album with longtime collaborators Union Station since 2004, is a calculated visual abstract of the nature of this musical partnership. Surrounded by the earnest gentlemen of her band in their minimal 19th century attire, Krauss is glamorous and ethereal. She seems poised on the cusp of floating gently away from their sepia company and the spartan field tent they occupy. The evident wind-machine manipulating her golden locks diminishes the effect of the Civil War-era setting, but then Krauss would tend to upend such purposeful anachronism even without any unseen modern trappings.

Despite their central role in the popular re-emergence of bluegrass over the last couple of decades, the alliance between the silver-voiced Krauss and the elaborate, rustic technicians of Union Station has always been marked by a productive tension between the faded rural world and the modern urban one. Krauss’ tone of tensile delicacy and exquisite rise-and-fall phrasing has become a staple on both pop and country radio at least partly because it tenderly shifts the axis of bluegrass away from the past and into the present, and she has pulled along her collaborators as well. Bluegrass, like all country music, is at its heart inescapably nostalgia-reliant. But country’s great leap forward in the corporate music marketplace was predicated on the genre trading a measure of its traditional longing for the brazen, polished immediacy of contemporary pop, and bluegrass was not entirely immune to this seismic change.

Krauss and Union Station are rarely brazen or immediate, but theirs is most certainly a very polished sound. As lovely as their songs (a mix of traditional tunes and originals penned by Robert Lee Castleman) can be, they sparkle with such precise and contemporary production that the essential, rough-edged alchemy of the genre is lessened. In a live setting, the banjo work of Ron Block and Jerry Douglas’ Dobro resonator guitar lines gallop away in rapid backwoods fury, but such virtuosity feels more assembly-line on studio recordings (for this reason, a 2002 live double album remains my favorite release by Krauss and Union Station).

Paper Airplane doesn’t challenge the formula, even if it features ample ghostly romance and impeccable melodic arrangements. The title track is also the lead single, and it isn’t hard to see why: this sort of hermetically-sealed prettiness is hard for radio programmers to resist, and why wouldn’t it be? Krauss wrings every scrap of available beauty out of the chorus with smooth confidence; resistance may not be futile, but it’s rather cumbersome. A stronger cut is the elegiac Richard Thompson cover “Dimming of the Day”, featuring a signature solo from Douglas; “Miles to Go” is also notable, sliding by with subtle rhythm. And, as always, the numbers featuring the soaring Appalachian tenor of Dan Tyminski (best known as George Clooney’s singing voice in the Coens’ bluegrass love-letter O Brother, Where Art Thou?) ramble away on a whole different wavelength. Tyminski’s vocal showcases are invariably more traditional in both their sound and subject matter than those sung by Krauss. The rolling, banjo-heavy “Dust Bowl Children” is the best of his tracks, although “Bonita and Bill Butler” has a bit more verve to its storytelling.

Coming after the striking creative departure of Raising Sand, her spare and haunting Grammy-sweeping collaboration with Robert Plant and producer T. Bone Burnett, Krauss’ reunion with her old mates feels well-worn and familiar. And, it might be said, overly so; an old shoe being slipped on with nary a conscious thought of how it might look. To be sure, the attempted follow-up to Raising Sand was an apparent bust. Plant humorously blamed the failure on an excess of craft services (public conflict and discord are less desirable in adult-contemporary circles than, say, in hip-hop) and then cobbled together some other Nashville musicians to make the fantastic Band of Joy album last year. Krauss’ retreat to more familiar creative surroundings is understandable, if perhaps not as praise-worthy. Her partnership with Union Station has been a fruitful one, in its way, but after giving us glimpses of more, she’s also made us expect more. Paper Airplane is sufficient, but doesn’t ever slip the bonds imposed upon it.

• Multiple songs MySpace