The institution had put out a call, on social media and from the stage of the march at Parliament House, for participants to drop off their protest signs so they could be preserved and added to its collection, all vital - and vibrant - pieces of social history ephemera.

More than 100 signs were dropped off, but also other protest pieces including a leather jacket with the names of women on the back and a baseball cap, explaining the wearer had marched for the women who couldn't. There were also black brooms with signs attached and a toilet seat asking: "When will this crap stop?"

Thousands of people attended the march on Monday outside Parliament House demanding action on "gendered violence".

National Library's assistant director-general responsible for collections Kevin Bradley and Dr Shirleene Robinson, director of curatorial and collection research, said the response was heartening and confirmation the protesters trusted the library to preserve history as it was happening.

"They were at the door as the march was breaking up," Mr Bradley said.

The library also collected digital items related to the march, part of its mission to document events - not just keep books.

"The signs will become part of our ephemera collection which will stand with many of the other things people can use to document, research and understand events that have gone on in Australia," Mr Bradley said.

The signs could be used in a future exhibition, but none was yet planned. They could also be requested for viewing in the reading room. The signs would be stored in-house at the library, rather than at its Hume or Mitchell warehouses, like most of its Australian material.

"There's no reason this kind of material couldn't be brought out to a researcher in the reading room," Mr Bradley said.

"But we also have a program of digitising our collections and placing them online and making them available."

Dr Robinson said it was important the library collected material that was part of the nation's social history.

"This movement has generated a lot of really rich and creative posters and I think for the future it will be really important for people to access those, to get a sense of what people were feeling at the time and to connect with that part of Australia's past," she said.

"I think that it was quite inspiring for us all to see people bringing their material to the library and hearing from the women who were dropping off their posters that they were really delighted that they were going to be kept for the future. It's a really lovely thing for us at the library, too, to know we were part of collecting that material."

Mr Bradley said the library decided to collect the signs from March 4 Justice, as soon it was announced, also commissioning photographers for the Canberra and Melbourne marches to further document the events.

Some of the protesters included their names and contact details on the signs, keeping the door open in the future for their oral history of the event to also perhaps be collected.

"That just shows a great awareness of people of how important these records are," Mr Bradley said.

"That's something we've seen quite often, there is a trust in what the library can do and an awareness that we are an organisation that cares for these things but collects without bias or favour. We just collect, broadly, to document."

With the march in Canberra taking place on a bright, sunny autumn day, the signs were in mint condition, with no rain or other damage

"I think there was a real sense, as people were dropping these off to us, that they would be looked after," Dr Robinson said.

"There was a feeling this was an important moment in Australia's history and they were pleased the library was doing what it always does and making sure that was represented in its collection.

"The interesting thing is a lot of these weren't created to be kept in perpetuity and it'll be interesting work again for the people who do the conservation and preservation in the library to make sure they do endure into the future. And I know they are looking forward to that challenge."

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