No match for the visual stimulation we get trawling through digital junk mail on the internet, the brochures targeted an audience in much the same way as online merchants do today.

Before computers and television, machinery merchants used rail and roadside mailboxes to carry their advertisements to educate, entertain and persuade their rural clients. The library's ephemera officer Catherine Aldersey says the advertising they left behind gives insights into how people furnished their homes, what they needed to grow wool and wheat, how much money they had, the language they used and what was foremost on their minds.

Faded and sometimes mice-eaten, the material's value is rising. "The main value of ephemera is it's a primary source of material that tells the truth of the moment," Ms Aldersey said. "It gathers together massive insights with different points of view, unequivocal proof of a particularly moment in time."

Booklets and brochures sprang from manufacturers in the capital cities that flourished from wool and grain booms. Geelong may be reeling today from closures in aluminium and car-making factories, but in those bountiful years preceding commodity crashes the Victorian city was making trucks and tractors, potato planters, harrows and ploughs, all complemented by a huge spare parts industry.

From the 1900s, catalogues invite their readers, who rarely came to the big cities, and who needed machinery and may have bought clothes as an afterthought, into their pages with cover pictures of multi-storey emporiums on corner blocks. Inside the booklets are location maps and instructions how to organise and pay for rail freight.

Enterprising leaflets encouraged farmers to visit stores, spread the word on their products and pass on invitations to neighbouring farmers.

Today's Harris Scarfe's online catalogue shows bedroom, bathroom and kitchen appliances, men's shoes and women's underwear. Its forerunner, the Harris, Scarfe, Limited catalogue out of Adelaide in 1936 has saddles, ironmongery, harnesses and bridles for horses and camels.

A Sunshine harvester brochure from 1924 includes a long price list, others have technical drawings rich in detail that people kept to help research other products and to refer back to when they needed service or spare parts.

The McEwans mail order is a thick book with an index of every item you would expect to find at a major hardware store including clocks, fire buckets, horse shoes and a full colour paint chip sampling section at the back.

A network of ephemera scouts and library staff look out for material, most especially brochures that complete a series or an era, and can only imagine who will come searching for it in future - the social historian, biographer or PhD student writing his thesis on tractors. A typographer once came looking for design ideas.

"I get calls when people are doing cleanouts, moving house, downsizing or moving into a nursing home, or a relative has passed away," Ms Aldersey said.

"We walk a fine line, we know people could be making money from what they have on eBay, but feel it is better if publicly available. People entrust [ephemera] to us to look after and make it available to the public."

Material does not have to be in pristine condition, but useable. In deciding what to keep and what to pass over, the library avoids being too judgmental.

"In 20 years' time a Bunnings catalogue will become more fascinating with the passage of time," Ms Aldersey said.