Deep in the bowels of the NGV, artist Patrick Pound and curator Maggie Finch are sorting through boxes of vintage photographs. Sourced from eBay and junk stores, Pound is mounting them for framing, arranged in very specific themes.

One series features images of people reading. Here, a studious Victorian-era portrait. There, a holiday snap of a bored dad reading the paper in a hotel room. Another collection is people listening to music. The next is themed around light: glowing lamps, changing lightbulbs, a streetlight.

Pound is an artist with an unusual practice. He doesn’t take photos, or paint, or sculpt, or make videos. He collects and arranges. His new show at the NGV, The Great Exhibition, is an odyssey through his many collections of photos, objects and artifacts. It runs as part of the gallery’s sprawling Festival of Photography.

The show is enormous. There are 311 works from the NGV archives, some of which have never been displayed, and more than 4000 pieces from Pound’s own trove. The oldest thing is an Egyptian comb, which dates to about 1500 BC. The most recent is from February. The name of the show, The Great Exhibition, is grand and more than a bit tongue-in-cheek. “I love that extreme, mad idea that you could sum up the world in a single exhibition,” he says. “It’s hubris disguised as humour, really. It's tragicomic but it’s also melancholy.”

His selections from the NGV’s vast archive complement his own collections. It’s a rare chance to see David Hockney alongside a fourth-century Chinese mirror, or a Sidney Nolan alongside a used VHS tape of Titanic. Pound isn’t necessarily interested in stuff of historical importance, or of great artistic merit. He was considering using a Picasso from the collection, but hasn’t. “He didn’t make the cut,” he laughs. Pound laughs a lot when discussing his work.

Instead of Picasso he’s gone for forgotten holiday snaps, cheesy portraits and tacky advertisements. It’s a conceptual project, but a playful one. “I’m not taking the piss out of things,” he says. “The works survive on their own merits. I love the way the meaning of things can change. I like making photos do things the photographer didn’t mean them to.”

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It’s a path he began nearly 30 years ago. “I was collecting material to inform my work, and eventually the collections became the work,” he says. “I stopped interfering with them.” As his practice has grown, it’s become more than just a collecting habit. Pound now accommodates his trove of images and paraphernalia across an offsite storage unit, his studio, and his house. It’s all “crazy full”.

Does he consider himself a hoarder? “No. Because it’s work,” he says. “I’ve segued my obsession into an art practice. That legitimises it.

“But my family definitely do.”

He’s constantly searching online for material. He puts every search through Google Translate to make the search in different languages, broadening his reach. "The internet is one vast unhinged family album,” he says. “It’s international, across class race and gender."

I meet Pound a couple of weeks before his NGV show opens. He still isn’t finished adding things in. “I’m always buying,” he says. He gets out his phone and checks eBay. “I’m buying right now.”

He’s bidding on a 1950s photo of two people with their back to the camera. It’s just gone to $6.05. He bids again. Then it’s on to a hand-coloured photo of a man in a suit, taking a photograph, shot through a distorted mirror. His face is hidden behind a camera. “This is a beauty, and it’ll go for quite a lot,” he says. “Sometimes I’m up against proper collectors of photography.”

Finch, the curator, seems nervous that he’s still adding to the show. Everything needs to be formally catalogued, and with more than 4000 pieces, Pound isn’t making it easy. He picks up a shopping bag and admits that he’s just also brought in more: a few newspapers so he can cut out images of the Oscars Best Film blunder.

I tell him I can imagine him walking through his exhibition on the day of the launch, blu-tacking more work. Finch glares at us across the room. Pound laughs.

Patrick Pound: The Great Exhibition is at NGV Australia until July 30.