Business reporter, BBC News
As the production line grinds to its own industrial beat, it's clear that music formats don't get any more physical than this.
Downloads and iPods are all very well, but for many musicians, your latest song just hasn't been released until it's been forced on to a small, grooved plastic disc at a pressure of more than 2,000 lb per square inch.
The Wombats and Franz Ferdinand are among the artists whose seven-inch vinyl records are being sleeved and boxed at the Portalspace factory in Hayes, on the edge of west London.
As it happens, they are the latest in a venerable tradition.
The 45 rpm single is about to reach its 60th anniversary and despite repeated predictions of its demise, sales are rising once again.
"Have a feel of that," says a passing engineer, handing over a white vinyl off-cut that has just been trimmed from the edge of a newly-manufactured disc.
It is warm to the touch - literally hot off the presses.
"That'll warm you up on a cold day," he says. "And we can recycle that and use it again."
Hue and cry
Most people think of records as being made of black plastic, but it turns out that coloured vinyl is as old as the seven-inch single itself.
The first 45 rpm disc, Texarkana Baby by country-and-western singer Eddy Arnold, was issued by RCA in the US on 31 March 1949.
It was made of green vinyl, as part of an early attempt to colour-code singles according to the genre of music they featured. Others included red for classical music and yellow for children's songs.
But such novelty features were left behind when the advent of rock and pop turned the 45 into the music industry's most prized product.
Seven-inch sales peaked in the UK in 1979, when a staggering 89 million of them were sold, but once the CD hit the market, vinyl of all kinds went into sharp decline. In 2001, annual singles sales dipped below 180,000.
The Portalspace factory has experienced both the highs and the lows of the single's history. It used to be EMI's main manufacturing site, churning out million-sellers by the Beatles and Queen, among others.
At its zenith, it employed 14,000 people, but EMI sold off the factory in 2000 when it decided to get out of the vinyl business. Now Portalspace has just 30 employees on much smaller premises.
Roy Matthews, who used to run the factory for EMI and is now Portalspace's general manager, says production of the seven-inch format dwindled to "almost nothing" at one point, but is now healthy again.
"Although we almost pronounced its death eight or nine years ago, it's now revived itself enormously," he says.
That rebound is reflected in UK sales figures for seven-inch discs, which have now risen to more than one million a year, most of them pressed at Portalspace.
But who is actually buying all these singles? According to the British Phonographic Industry, which represents the British music business, a new generation of bands is attracting younger buyers.
The BPI says the "popularity of bands such as Oasis, White Stripes [and] Arctic Monkeys" is reviving sales of the seven-inch, while record companies are also credited with using "innovative" strategies to highlight the format.
In 2007, the White Stripes and their label, XL Recordings, gave away a red vinyl single mounted on the cover of the NME weekly music magazine.
It came in a gatefold sleeve with space to hold the band's commercial release, Icky Thump - a promotion that resulted in the highest sales for a vinyl seven-inch in more than two decades.
Another XL artist, 24-year-old singer-songwriter Jack Penate, is an especially keen fan of the 45, despite the fact that he wasn't even born when the format was in its heyday.
To launch his career, he released a limited-edition single that featured a unique Polaroid photograph stuck to the front of every copy.
As well as making singles, he also collects them and even DJs in clubs using just seven-inch records.
"What I love about seven-inch singles is the sound quality and the warmth, and also that they're physical, and I will keep them forever and I cherish them. They're not throwaway," he says.
"I always feel that if you download music, you rarely listen to it over and over again, whereas most of my singles have been played hundreds of times."
The BPI admits that seven-inch singles may be even more popular than its figures suggest, since they are based on shops that report to the Official UK Charts Company, which compiles the weekly Top 40.
As it acknowledges, many singles are sold through specialist retailers, which do not necessarily have their sales figures canvassed for the charts.
At one such retailer, Rough Trade East in London's Brick Lane area, seven-inch singles are prominently displayed.
The shop's co-owner and manager, Nigel House, says they are an important part of its stock.
"They get people into the shop, buying records," he says.
"Obviously, you make more money selling a CD, but there's nothing like seven-inch singles, especially for the music aficionados.
"They're tactile, they have fantastic sleeves, they sound great, they're concise. Pure pop."
But despite the healthy sales figures, today's vinyl record buyers may be treating their purchases as cult objects, rather than actually playing them.
HAVE YOUR SAY I can still remember the excitement of buying a vinyl single on a Saturday morning Claire Herbert
"A lot of the kids who buy these seven-inches probably don't have record players," says Jack Penate. "I think it's a lot more that they love looking at them.
"For them, it's something from a lost era. Maybe it makes them feel more like a real fan. They've got something physical, instead of MP3s, which are completely 'non' - there's nothing to hold or see."
That lost era took another step further into the past recently, with the demise of one of the most important stockists of old vinyl singles.
Beanos of Croydon, in south London, used to be the biggest second-hand record shop in Europe, with its Singles Bar department boasting copies of virtually every seven-inch to make the charts since their inception in 1952.
But the shop has been struggling to survive for the past two years, and is set to close by March 2009. Beanos has already disposed of its last remaining singles, with only CDs and vinyl LPs still in the racks.
Owner David Lashmar plans to open an indoor market in the same building, but he admits he will miss his 30 years as a dealer in seven-inch 45s.
"Back in the late 1950s, buying a seven-inch single, having it at home, taking it down the youth club and impressing the birds with it was a really important thing to do," he says.
"That was all I could afford. A seven-inch single was pitched dead right. It was an indulgence, but it would give you status."
Those heady days will never return. But for many music lovers, the snap, crackle and pop of vinyl remains very much alive.