He made his fortune with industrial hardware and used it to collect priceless art, from medieval treasures to modern masterpieces by Pablo Picasso, Henry Moore and Andy Warhol.

German billionaire Reinhold Wuerth, 80, known as the "screws king" for his global business empire, has since the 1960s built up one of Europe's largest and most glittering private art collections.

From Friday, 400 of his works go on show in Berlin's Martin Gropius Bau gallery under the title From Hockney to Holbein - a crowning achievement for Wuerth, who built up the family business from his humble beginnings in the postwar years.

Among the highlights of the show, set to run through Jan 10, will be David Hockney's season cycle, sculptures by Moore, modernist masterpieces by Picasso and Edvard Munch, and a 16th-century Madonna painting by Hans Holbein the Younger.

Wuerth, who retired from running the group in the 1990s, has focused on the almost 17,000-piece collection as his enduring passion.

"That's the only thing I'm still keeping for myself," he says, with his eyes lighting up.

Were it not for his expensive passion, Wuerth would be the archetypal corporate patriarch of the German "Mittelstand", the often rural-based and family-run businesses that make up the backbone of Europe's biggest economy.

Born in 1935, he started as an apprentice in the small hardware business, selling screws and bolts, which his father Adolf had started in 1945, as Germany lay in ruins after its World War II defeat.

When his father suddenly died in 1954, Wuerth was 19 years old. He took over the family business, which at the time had just one other employee.

Germany's postwar "economic miracle" saw sales explode, with growth of 60-70 percent a year, as the business started to deliver its goods directly to mechanics, workshops and building sites.

"Everyone needed screws and bolts," Wuerth recalls.

Last year, the Wuerth Group - which makes assembly and fastening materials for the auto, construction and engineering sectors - employed 68,000 people and operated in some 80 countries, with an annual turnover of more than 10 billion euros ($11 billion).

"I would never have believed that we would one day be that size," says one of Germany's richest men.

Wuerth started his hobby in the 1960s, and has built up an art collection that spans many epochs and styles, with cubists, expressionists and contemporary artworks abundantly represented.

"Wuerth's talent lies in finding works - often directly from the artists - and in establishing connections," says the host venue in advertising the show, calling the businessman "a collector of collections".

In 2011 he laid down more than 50 million euros for the Madonna painting by Holbein the Younger, in postwar Germany's most expensive art purchase.

Since the 1990s, works owned by Wuerth have been shown in some 15 European galleries and museums, including in France and Switzerland, as well as in company sites.

"Mr Wuerth wants everyone to enjoy his art," says the director of the collection, Sylvia Weber.

Wuerth says that over the years his passion for art had "contributed greatly to the development of the group.

"People see that we're not just boring industrialists obsessed with growth," he says.

(China Daily USA 09/15/2015 page9)