Storage, Display and the Ninety Per Cent

The ninety per cent figure has a source, and it is a survey

The claim that museums show only a fraction of what they hold is repeated so often that it has become a slogan, usually without a number attached and never with a citation. The number exists and it has a literature. A joint UNESCO and ICCROM international survey in 2011 found that around ten per cent of museum collections were on display and ninety per cent in storage. A study of museums in England and Wales published by Keene and colleagues in 2008 reached a comparable figure of eighty per cent stored. Two decades earlier, Lord and colleagues had estimated eighty to ninety per cent across UK museums, disaggregated in a way that is more useful than the headline: archaeological museums around ninety per cent, art museums seventy to eighty.

The most recent measurement, published by Corona in the journal Collection and Curation in 2025, gives an average of seventy-four per cent of collections in storage and twenty-six per cent exhibited in galleries. Of the stored portion, about thirty-two per cent was made accessible through some form of visible storage, leaving roughly half of a typical collection genuinely unseen. The same study found visible storage in seventy-eight per cent of small museums, fifteen per cent of medium-sized ones and only seven per cent of large ones, and identified the constraints directly: seventy-one per cent of respondents reported inadequate staffing and sixty-eight per cent insufficient budgets.

Those figures differ from each other because they measure different populations, and the honest summary is a range rather than a point. Somewhere between seventy and ninety per cent of a typical collection is not on view, the proportion is highest for archaeology and lowest for painting galleries, and it has not moved much in thirty-five years.

The reasons are structural, not negligent

The most common misreading of the ninety per cent is that it represents hidden masterpieces. It does not, and the composition of collections explains why. The British Museum holds on the order of eight million objects and displays around one per cent of them at Bloomsbury; that figure is dominated by coins, potsherds, flint tools, seals and prints, categories collected in series precisely because the series is the evidence. Displaying a hundred thousand Roman coins individually would not teach anyone more than displaying two hundred well.

Light is the second constraint, and it is absolute. Works on paper, textiles and photographs have cumulative exposure limits, which is why print rooms rotate rather than hang. A drawing shown for three months every five years is not being withheld; it is being kept legible for the next century. Watercolours, dyed fabrics and albumen prints all sit under the same regime.

Space is the third. Galleries designed in the nineteenth century for collections a fraction of their present size cannot absorb a hundred and fifty years of accession, and the alternative to storage is not display but disposal, which the professional codes restrict severely and for good reason. The proportion in store is a direct function of the fact that museums acquire faster than they build.

Open storage has become a building type

The institutional response of the last decade has not been to display more but to make storage itself visitable. The Depot Boijmans Van Beuningen in Rotterdam, opened in 2021, holds more than 155,000 objects across fourteen storage compartments and describes itself as the world's first publicly accessible art storage facility. Access is by online ticket, with short guided walk-ins into the compartments themselves limited to about thirteen people and lasting roughly ten minutes. The model is deliberately not a gallery: visitors see racking, crates and climate zones, and the point is the infrastructure.

V&A East Storehouse opened in Stratford on 31 May 2025, designed by Diller Scofidio and Renfro across four levels and some 16,000 square metres, holding more than 250,000 objects and 1,000 archives from a museum collection of around 2.8 million. Entry is free and daily. The significant innovation is not the building but the booking system: Order an Object lets a visitor request up to five items two weeks in advance, with a projected capacity of 25,000 appointment slots a year, seven days a week. The Department for Culture, Media and Sport provided a principal grant of 50 million pounds, with further support from the Garfield Weston Foundation, the Foyle Foundation and Frederic Jousset.

The Louvre's Conservation Centre at Lievin, inaugurated in 2019 next to the Louvre-Lens, was built for a different reason and reveals a different problem. The Louvre sits on the bank of the Seine, and in a flood there would not be time to evacuate works from underground storage covering nearly 10,000 square metres. The centre consolidated holdings previously scattered across more than sixty locations inside and outside the palace, and was planned to hold around 250,000 works by 2024. It functions as a study centre where curators, conservators and external researchers consult objects, and the Louvre has stated it could shelter works from countries in armed conflict at the request of the owning states.

Digitisation changed what access means, and what it does not

On 29 March 2021 the Louvre published its collections database online with more than 482,000 entries, covering works on display, works on long-term loan to other French institutions, works in storage, and the MNR paintings recovered after the Second World War and held pending restitution. For the first time the museum's holdings could be interrogated by anyone, including for objects nobody could physically see. The parallel in provenance research is the Getty Research Institute's index of the historic art market, which has made auction records searchable at a scale no library visit could match.

What digitisation delivers is discoverability, and discoverability is the binding constraint for researchers far more often than physical access is. A scholar who can establish in an afternoon that an object exists, where it is, what it is catalogued as and what its inventory number is has had the expensive part of the work done. The request to see it is comparatively cheap.

What digitisation does not deliver is examination. A photograph will not show you a panel's join, a canvas's cusping, a pentimento or the difference between abrasion and glazing, and the technical questions that decide attribution and condition require the object under raking light. The Corona figures on staffing and budget explain why the gap persists: making stored objects retrievable on demand is a labour cost, and it is the cost museums are least able to absorb.

What the open-storage decade has actually changed

The display ratio has not moved. V&A East Storehouse did not increase the proportion of the collection on formal display; it increased the proportion that a member of the public can lay eyes on, which is a different and arguably more useful metric. Rotterdam did the same. The Corona study's distinction between the thirty-two per cent of stored material made visible and the fifty per cent that remains in closed depot is the number to watch, because it measures the thing these buildings were built to change.

For a researcher the practical consequences are concrete. Object-level online catalogues mean the first search should be the museum's own database rather than the literature. Appointment systems at Rotterdam, Stratford and Lievin mean that a stored object is now bookable by an outsider rather than obtainable only through a curatorial contact, which removes a barrier that quietly shaped who did provenance and technical research for a century. And the shift of storage out of city centres, to Lievin, to Stratford, to purpose-built resource centres, means the object you want may be sixty miles from the gallery that owns it.

The ninety per cent was never the scandal it was reported as. The scandal, such as it was, lay in the fact that nobody outside the building could find out what the ninety per cent contained.