The Sword have a logo that reeks of 70's-grade LSD and jeans worn for weeks on end; the sort of logo that wouldn't look amiss on an old pulp fantasy paperback, or an album cover found in the loft of a disreputable uncle. This is a good thing. I believe in honesty in advertising, and the Sword are letting the packaging describe the contents.

They take the stage with little ceremony; four hirsute stoners looking slightly shell-shocked and barely out of their teens, scrunched up near the front edge of the stage by the headline act's kit. A mumbled greeting, and then the music starts.

And it's huge. Monstrously so.

Granted, the Sword aren't going to win any prizes for originality, but nor is anyone else in this relentlessly post-modern musical climate. Nowadays you succeed by doing something that's been done before, but doing it bigger, better and with your own unique top-spin. The Sword seem to understand this.

The Sword also understand how the music they love needs to be performed. The name you give to that form of music depends on which angle you come at it from: it's been called sludge rock, doom rock, desert rock and stoner, and probably a few other names along the way. The defining characteristics are stately nodding tempos; simple monolithic riffs played on drop-tuned guitars; deep deep bass that makes your cock shake around in your trousers, and vocals that only serve the purpose of filling in that part of the audio spectrum. Pure metal, boiled down and rendered to the bare essentials, with none of the wankery, frills and bombast that frequently get bolted on top; the sound of the 70's turned up to eleven.

The Sword have practised these songs, and they play them tighter than a rush-hour tube-train. The drums thunder and rumble, pinning down the heaving slabs of guitar and bass and holding the whole edifice together. It's as if they're trying to summon the ghost of Tony Iommi from a Valium coma, all the while completely unaware he's not actually dead yet. It's relentlessly powerful, almost architectural stuff, decorated with howling bluesy hooks at the end of each four bars or so and punctuated with drum fills that Animal the Muppet would be jealous of. The riffs never outstay their welcome, either, moving into a new section or theme at just the right moment to avoid losing the audience's attention. I find myself wishing they had done the soundtrack for the 'Flash Gordon' movie instead of Queen – if I ever get the chance to ride a rocket-ship to another dimension, this is exactly what I want on the stereo. To judge by the enthusiastic audience response during and after each lengthy track, I am not alone in this opinion.

And that's it. Their twist, their unique selling point, is that they don't have one. They don't need one. The music speaks for itself – as it has to, for we hardly hear ten words scattered between a short set of long songs. The Sword have strength, they have pace, and they have an astute sense of movement that evokes long journeys - be it through space, along desert highways or down to the bottom of the bong-water. Give them a year or so, and they'll have a stranglehold on their subgenre too.

Especially when you consider that they're touring as support to one of the best known and longest running stoner bands in the history of the style. Clutch have managed to avoid the untimely splits, issues-and-rehab see-sawing and early burnout that removed a lot of their original contemporaries from the running. Clutch are survivors. They've never been huge, but they've been consistent, selling out mid-sized venues year after year, putting in the hard slog on the festival circuit, paying their dues.

And with age comes experience, stamina and growth. Clutch are confident, but not cocky, almost to the point of being somewhat self-deprecating. Seemingly powered by beer-guts and facial hair, they perform for well over an hour, with no breaks and no encores. They've found their own niche, developing over time into a high-octane interpretation of Deep South roadhouse blues-rock, heavy as hell but deceptively light on its feet.

Because Clutch have learned the value of space in their music, the value of breathing room. Where the Sword erected a solid wall of overdrive, Clutch produce something that sounds impossible when put into words – they make metal with grooves. While there is always something happening, there is never too much going on at once. The songs move from crunching all-out intros, through verses marked by muted guitars and judicious cowbell usage, into moments of deceptive calm, the brief eyes of five-minute musical storms that blow into town from the Gulf Coast and wreck the neighbourhood. The vocals exhort like a whisky-befuddled street preacher, and the guitars have wah-wah drenched solos wrenched and squeezed from them. It's like watching a fight in a biker bar – brutally compelling, despite the risk of getting too close.

They've added some new tricks, as well. A few songs have brief Hammond organ sections, and the addition of a hyperactive harmonica player adds an extra layer of sleaziness to the last three or four songs. It's music to drink and nod along to, wryly knowing hill-billy heavy metal that takes itself seriously enough to be a polished and powerful performance, but lightly enough to not fall prey to the leather-and-studs imagery that lesser bands need to make themselves look tough. Clutch are the real deal, and their toughness comes from well-polished musical skills and a ferocious dedication to their profession – they have attitude, and no mistake, but it's not forced, fake or foolish. It is easy to imagine them still touring the same venues in a decade or so, a little greyer and thicker round the middle, but still doing what they do and putting everything they have into it. In a world full of fifteen-minute next-big-things, it strikes me that they have a damned sensible business model, as well as an untainted product that improves with age.


The photographs that accompany this article were taken by Katie Anderson exclusively for Pennyblackmusic