What happened to Ben Franklin’s three-piece suit?

Last spring the Smithsonian announced that it had added the 230-year-old outfit to its permanent collection at the National Museum of America History. But now the silk getup that Franklin wore as a diplomat in the salons of Paris is nowhere to be seen. Who decided to replace it with the gold damask frock of a Southern aristocrat?

Why is the Hirshhorn Museum displaying Jean Dubuffet’s ‘The Soul of Morvan,” a gnarled little man made of grape wood and vines mounted on a slag and tar base, but not the same artist’s “Butterfly-Wing Figure,” a collage made from, yes, butterfly wings and considered by some to be one of the collection’s most charming items?

Why isn’t Johannes Vermeer’s tiny but dazzling “The Girl With the Red Hat” on view now at the National Gallery of Art?

Walking across the National Mall, you’re tempted to think that architects and legendary collectors shaped Washington’s museums, and they did. But curators, who make the thousands of this-but-not-that judgments, who pluck one work from the storage vaults and send another away, shape them even more.

Benjamin Franklin, with his unadorned clothes and speech, and his fur cap, quick wit, and humble charm, came to symbolize for many what it meant to be an American during the Revolutionary War. In Paris to help negotiate an alliance with France, Franklin stood out at the court of Louis XVI with plain clothing such as this silk suit. (Harold Dorwin, Smithsonian)

Together, the city’s curators have something like 140 million things to choose from but no more than 1 percent of these are on view. Most of the rest are in exile, awaiting a chance to return.

Light sensitivity keeps many things in the closet. Works on paper — watercolors, drawings, etchings, photographs, maps, documents — deteriorate. At the Corcoran Gallery, for example, the rule is that a photograph on display for six months must go back in storage for six years. The museum, like many others, has a space devoted to photographs, but the pictures are constantly changed.

The story’s the same with Franklin’s clothes; light has already faded them from the original plum to a husky brown. The suit can be shown only for a few months at a time, so when it goes back into storage, curators rotate in another garment from the same period.

Curators don’t have a lot of wiggle room in choosing how long such objects can be displayed.

When it comes to the most famous works, curators don’t have much leeway either. People who go to the Phillips Collection expect to see Jean Renoir’s “Luncheon of the Boating Party,” which shows rosy-cheeked revelers at a café on the Seine. One of the most famous pictures in Washington, it never goes into storage. The same goes for the Wright Brothers airplane, the Hope Diamond and the National Gallery of Art’s jewel-like paintings by Vermeer. (The National Gallery occasionally loans its Vermeers to other museums, which is why “The Girl With the Red Hat” isn’t up.)

And some items almost never get out of storage. The Freer and Sackler Galleries, which hold the Smithsonian’s collection of Asian art, own lots of pottery shards. They’re invaluable for scholars, but not much to look at.

Between “Luncheon of the Boating Party” and the rarely seen shards is a vast array of objects in the middle — items worth showing off but not musts. That’s where curators earn their keep.

Their decisions sometimes come down to what kind of conversations a work can have with other art around it. Dorothy Kosinski, director of the Phillips Collection, talks about creating “constellations” of art. Her metaphor captures a magical thing about museums: Artworks can take on new meaning because of their relationship with nearby works, just as three bright stars take on added meaning when we see them as Orion’s belt.

At the Museum of American History, curator Paula Johnson and three other curators are building an exhibition around Julia Child’s kitchen. Their aim is to get people to think about how America’s eating habits changed in the last half of the 20th Century. They have included some odd items: a TV dinner, a ’60s TV tray and — one of Johnson’s favorites — a Krispy Kreme Ring-King Junior doughnut machine. She is also hauling out bottles of two California wines that won international respect for American winemakers when they won first place at a blind tasting in Paris in 1976. (The breakthrough wines: 1973 Chateau Montelena Chardonnay and 1973 Stag’s Leap Wine Cellars Cabernet Sauvignon.)

Her constellation will send all sorts of ideas Ping-Ponging around people’s heads: the influence of French cooking on Americans (Julia’s pots and pans), America’s growing sophistication (wine), how culture reshaped mealtime (why talk to Mom and Dad when you can stare over your food at the TV?) and our sugary preoccupations (hello, Krispy).

In recent years, museum curators have begun to mine their own collections more and more.

“The days of the blockbuster exhibition are over,” says Philip Brookman, chief curator at the Corcoran Gallery of Art. Economics have shifted, particularly the cost of insuring borrowed masterpieces. Lending museums are tired of coughing up their most famous pictures, too. So permanent collections are coming to the fore.

Washington’s largest permanent collection — and one of the largest in the world — is at the Smithsonian’s National Museum of Natural History, which has 127 million items, 12 million of them beetles.

The collection is so vast the museum staffers can’t dig through its entirety. So they reverse-engineer displays, explains Jonathan Coddington, a spider expert who is acting director. First, they decide what scientific stories they want to tell. Then they find the objects that best convey the story. And because science is less fickle, an exhibition, once up, can stay up for 20 years.

Art curators do much more shifting. How each one deploys a collection is shaped by a museum’s mission. The Hirshhorn, says Chief Curator Kerry Brougher, is a progressive institution that tries to stay on the leading edge of art. That may mean displaying only one or two of its many paintings by Thomas Eakins, whose masterful realism captured important images of the late 19th century, and more wall drawings by Sol LeWitt, whose work in the second half of the 20th century explored geometric forms.

But shouldn’t there be ways people can see treasures that are in storage?

It turns out, there are.

First, most Washington museums are putting digital images of almost everything in their collections online. You can search the Hirshhorn’s site and see both of the Dubuffets mentioned above and find out which one is on display. (The fragile “Butterfly-Wing Figure,” which needed a rest, will be back next spring as part of a special collage show.)

Second, at many museums, it is possible to make an appointment to see items in storage. The National Gallery’s works on paper and photographs departments and the Freer’s Asian art staff are among those that allow any person access to the collections, though you do need to make arrangements in advance.

But the most innovative solution is something called open-storage galleries. The American Art Museum is one of a handful in the country that employs it. The museum has packed about 3,300 artworks into 64 glass cases. Visitors can cull through case after case of works they would never see otherwise.

Inside a drawer on the third floor, you can press a button and open a glass-topped drawer that contains an elliptical ivory box with a painting—watercolor on ivory—of a woman’s eye. The image is little bigger than a thumbprint. Because it is so delicate and small, it wouldn’t normally be on display. But because it sits in a dark drawer until visitor opens it, the eye can always be there.

Painted around 1800, it is believed to be a man’s reminder of his secret lover. The lover’s identity remains a mystery, and looking at it is a reminder of the thousands and thousands of secrets stored in the vaults of the city’s museums.

John Pancake was arts editor at the Washington Post from 1996 to 2008.

Food: Transforming the American Table

“FOOD: Transforming the American Table, 1950-2000” opens Nov. 20 at the Museum of American History.