Post-rock, as a genre, has always been difficult to define or explain. Yet, for Portland-born Grails — whose members now live in three different cities on two different continents — definitions and descriptions grow even more complicated as the years pass. Ostensibly a post-rock band by default of their catalog of instrumental music played in the rock idiom, Grails have long existed in the narrow overlap between psychedelic rock and film scores, with elements of ambient, trip-hop and metal. The music that Grails make is complicated and nuanced — not the kind of sound that one files away under one label so easily.

Chalice Hymnal, out this week via Temporary Residence, is the first full-length from the band in six years, as well as their most eclectic to date. The group’s various members have spent the time since 2011’s Deep Politics engaged in other projects: Emil Amos and Alex Hall in beat-driven project Lilacs & Champagne, Amos in solo project Holy Sons and doom metal band Om, and Zak Riles as a farmer in Kentucky. And based on the sound of the album — which veers between mournful, string-driven dirges and guitar-heavy freakouts — that time was also spent absorbing as diverse an array of musical influences as possible.

Hall, Riles and Amos took some time to answer questions about their unintended hiatus, the freedom of being an underground band and the ambiguous musical space they occupy. Soundtrack our interview with a full stream of Chalice Hymnal.

Six years have passed since Deep Politics — the longest gap between any two Grails albums. How much of that time was spent working on new music, and how much of it was spent on separate projects?
Alex Hall: The gap wasn't really planned at all; just lots of other shit going on and life changes. Emil moved to New York, and I moved to Germany. Zak started a farm in Kentucky, and a band called Watter. Emil and I put a lot of work into Lilacs & Champagne, and also Om and Holy Sons for Emil. But it feels amazing to bring Grails back from the near-dead; we're super excited now for the next chapter of the band.

After Deep Politics, was there a specific direction that you felt pulled toward, stylistically?
Zak Riles: Like any Grails record, it’s a reflection of the records we've been listening to, and the songs get pulled in those directions. For me, it’s been so long that I had to ask myself what Grails even sounds like, and then try to incorporate the new techniques I’ve learned into that sound.

There’s a song on the album called “Deeper Politics”; is there any deeper connection between this album and your last?

AH: It’s not to be taken very literally; it’s just fun to create narrative threads that run through the records. Like watching a TV series and having favorite recurring characters that make unexpected appearances. It pulls together the cosmology of the band and makes the records more exciting for us to work on.

On the note of politics, to what degree do they play into the music you make? The world looks a lot different now than it did in 2011.

AH: As an instrumental band, any overt political message would have to be slapped on, applied in the way of a bumper sticker. Which wouldn’t really suit the vibe of the band. But any music that helps people get out of bed in the morning and keep their heads up might be considered political these days.

Since everyone is involved in other bands, does it require a bit of extra effort to bring everyone back together to make a Grails record? Do you call a summit meeting?
ZR: It does require more effort, mainly because we all live in different cities. There are a lot of emails, group calls, texts, etc. It was much easier back in the days of meeting up down at Magic Gardens [a legendary Portland strip club that recently closed].

Grails aren't a band that does lots of long stretches of touring, and it continues to look that way for the time being. Do you intend to keep limiting live performances?
 The band has never been a major source of income, so we’ve never felt compelled to hit the road for months at a time. And, as ever, the primary focus is directed toward the studio, but I think we feed off of the energy that’s generated by the live version of the band to stoke our excitement for the recording process.
Emil Amos: We all grew up worshipping at the altar of local underground bands, so we didn't take the idea of "ascending" into the larger music world very seriously. Our "business model" will probably always be tied to the way we saw bands like Sun City Girls take advantage of the freedoms that being an underground band can grant you.

Because there seems to be no limit, in a way, to what Grails can be musically, does that present its own set of challenges?

EA: I was in a studio session the other day, and someone asked me what I've been working on — it was an odd challenge to try and explain what Grails is. I think I said that the band has been around for 18 years, and that the new record is something like if you flipped French '70s softcore porn soundtracks upside down, framing them in an evil, insidious atmosphere. So, the challenges are all within the realm of rendering what's stored in your imagination. The fact that this band has been allowed to do whatever it wants from the very beginning is really what's kept it alive for so long.