A Persian carpet decorated with swirling vines and vibrant flowers that was stored for decades by the Corcoran Gallery of Art sold Wednesday for more than $30 million. That sum, fetched at a Sotheby’s sale, shattered the previous record for rugs sold at auction. But it won’t help the struggling Washington gallery overcome its financial woes because the money must be used for future acquisitions, not to help the bottom line.

The winning bid for the Clark Sickle-Leaf Carpet stunned viewers and participants at the sale, in which 25 rugs and carpets were auctioned off to raise money for new acquisitions of American and contemporary art at the Corcoran Gallery. The anonymous bidder, who participated by phone, paid $33,765,000 for the 17th-century Persian piece, which came from the bequest of William Clark, the industrialist and U.S. senator who donated more than 200 works of fine art and rugs to the Corcoran upon his death in 1925. Before Wednesday’s sale, a blue leaf-patterned 17th-century rug from southeast Iran held the global record, selling for $9.6 million at Christie’s in London in 2010.

“I thought it might sell for 10 or 15 million dollars,” said Mary Jo Otsea, the auctioneer and senior consultant for rugs and carpets at Sotheby’s. The auction company estimated the carpet would sell for between $5 million and $7 million. “No one ever expected to see it on the market. Its beauty and rarity — the closest comparables are in museums.”

Which is why, Otsea believes, the carpet sold for such a high figure. Rarity pushes the value of art up, and most Persian carpets are subdued in patterns and hues. But the roughly 8-by-6-foot carpet is said to be the epitome of the “vase” technique, perfected during the Safavid dynasty in Persia. It was last displayed in Washington at the Sackler Gallery in 2003 and the Corcoran Gallery in 2006.

The Sotheby’s sale also comes as the classical carpet market — carpets made during the 16th and 17th centuries — is booming. A decade ago, only the most famous Persian rugs would sell for seven figures at auction. But collectors in Asia and the Middle East are investing in Persian rugs with the same enthusiasm they are showing for rare, valuable contemporary works. Museums in the Middle East are also investing in Islamic art collections, including the Museum of Islamic Art in Doha and the Guggenheim Abu Dhabi, now under construction. And renewed interest in Islamic art in the West has probably contributed to prices, too, with the 2011 opening of the Metropolitan Museum of Art’s New Galleries for the Art of the Arab Lands and last year’s opening of the Department of Islamic Art at the Louvre.

The Corcoran Gallery of Art’s Clark Sickle-Leaf Carpet, from the collection of William Clark, was sold at auction for $33 million. (Collection of William A. Clark; Courtesy Corcoran Gallery of Art)

As for who bought the record-breaking rug, it’s anybody’s guess. Sotheby’s never talks, and the Corcoran doesn’t know.

“It could have gone to the [Persian] Gulf countries, to Europe or to an institution being built somewhere,” said Peggy Loar, interim director of the Corcoran. “In terms of patrimony, or where these carpets came from, there’s great interest in bringing them home.”

“Islamic art museums want carpets from the golden age of carpet weaving, so that sector of the market has become increasingly more desirable,” Otsea added.

The auction brought in nearly $43,764,750 but Sotheby’s will take a portion. The Corcoran will not release the total proceeds, and Sotheby’s does not disclose its contractual arrangement with sellers. The sale was expected to net the Corcoran $6.7 million, the estimated minimum value of the 25 pieces on the auction block. The 16th- and 17th-century rugs from Persia, India and Egypt all sold for more than double their high estimates. Another valuable piece, the Lafões Carpet, an Isphahan carpet from Central Persia, raked in $4.6 million, far higher than its $800,000 to $1.2 million estimate.

“It was a great day for Oriental carpets and the Corcoran,” said Loar. “So many of these carpets had not been turned over to dealers since the 1930s, and there’s so few on the market in this field. It brings together everyone who’s interested in them.”

It’s good news for the Corcoran, a gallery that has been mired in financial struggles for much of the past decade. In 2005, the gallery shelved a Frank Gehry-designed wing with an estimated cost of $200 million after fundraising efforts fell by the wayside. Last June, the Corcoran considered selling its Beaux-Arts building on 17th Street NW after announcing that the building needed more than $100 million in renovations. Its operating budget is also in dire condition; according to financial records, the Corcoran ran a $7 million deficit in 2011 and would have incurred the same deficit in 2012 if not for the $18.8 million sale of a parking lot. Despite financial woes, Harry Hopper, chairman of the Corcoran’s board of trustees, said the timing of the sale was not directly related to the Corcoran’s ongoing financial woes.

As for whether the Corcoran will miss the carpets, Loar said the Corcoran is pleased to pass them on to collectors or institutions able to exhibit them. The carpets were stored off-site in temperature-controlled units, and while they were well-maintained, preservation was costly.

“I will say, since we don’t have any specialists in that area, it wasn’t as difficult for us [to sell],” Loar said. “These carpets deserve love, whether from a private collection or institution, and need to be stored properly. It’s an enormous financial investment to do that if not central to mission.”

Museums often deaccession, or sell, works that have been donated and no longer fit with the ethos or specialty of the institution. Many of the rugs, including the Clark Sickle-Leaf, have been in storage for years because they don’t mesh with the Corcoran’s contemporary exhibitions. The Corcoran’s deaccession policy prohibits it from using the money for operating expenses in accordance with museum standards. The money will go to an acquisition fund, which Loar said will enable the Corcoran to “follow through with a more focused vision that includes American arts, photography and design.”

David Montgomery contributed to this report.