The National Gallery of Art has around 3,500 paintings in its collection, and almost all of them are on permanent view in the galleries.
At last count the NGA also had 108,000 old master and modern prints, etchings, drawings, and other works on paper — by artists ranging from Albrecht Durer, Rembrandt van Rijn, William Blake and Giovanni Battista Piranesi to the American impressionist Mary Casatt and Pablo Picasso.
None of them is on permanent view.
Because the latter works are highly susceptible to damage by overexposure to light, the gallery stores them in specially constructed, climate-controlled boxes in darkened rooms — a museum within the museum. European works are kept in the I.M.Pei-designed East Wing, and American works in a similar space in the West Wing.
Out of sight doesn't mean inaccessible, however. Visitors can view any work in the collection in study rooms attached to both storage facilities, provided a request is made in advance to 202/842-6380. The museum receives more than a thousand such requests every year — and it's not just children with school projects.
Recently, said Gregory Jacmen, the print room supervisor, Durer's 1514 engraving "Melancholia" has been in great demand not so much because it's one of the most famous, but because it is featured in Dan Brown's latest novel, "The Lost Symbol," set in Washington. (In the novel, the main character, Langdon, examines a square of "magic" numbers in the picture.)
"Normally we show [prints] loose, but we had this one ddframed to keep it safe from too much handling," said Mr. Jacmen of the Durer. Other requested favorites include prints by Rembrandt and the wood engravings of the English poet and artist William Blake. The most popular American works include prints by Paul Revere, James McNeill Whistler and Casatt.
Parts of the print collection can also be seen in reasonably frequent gallery exhibitions. "It's a gigantic collection, and while we can't show everything, we can show many different things," says Andrew Robison, who is Andrew W. Mellon senior curator of prints and drawings. "We interchange, and the challenge is to create exhibitions which explore different areas of the collection. That gets the collection to the publc."
A display of the prints and drawings of the baroque master Giovanni Benedetto Castiglione (1609-1664) closed July 8, and an exhibition of works on paper produced in Augsburg, Germany, during the Renaissance is scheduled to follow on Sept. 30.
Called "Imperial Augsburg: Renaissance Prints and Drawings 1475-1540," the exhibition focuses on a period of innovation in print-making techniques in the Bavarian city that was seat of the Hapsburg court. Included in the show are some of the first prints in color, a technique developed by the printer Erhard Ratdolt (1447-1528).
German prints are less well known in the U.S. because American collectors have generally concentrated on the works of French and Italian artists. So in January we are on more familiar ground with "Drawings, Watercolors, Pastels From Delacroix to Signac" from the collection of Arkansas industrialist James T. Dyke — many of the works given to the gallery.
The gallery's works-on-paper collection began with 400 prints donated by five collectors in 1941 and has grown exponentially through donations and an active acquisition policy. According to Mr. Robison, the NGA acquires or receives as gifts about 1,000 prints, drawings, and other graphic items every year, compared with 30 paintings over the same period.
"On a piece-by-piece basis [prints] can be cheaper," acknowledges Mr. Robison, "but on an aggregate basis, prints can be quite expensive."
The NGA made its biggest purchase to date of prints and drawings in 2007. This was the Ratjen collection (from the estate of Lichtenstein banker Wolfgang Ratjen), which includes 66 Italian drawings from the High Renaissance until the end of the 18th century and 119 German drawings from 1580 to 1900. Among the Italian works is what the gallery calls Canaletto's "finest surviving drawing," "The Maundy Thursday Procession Before the Ducal Palace in Venice" (1766).
The NGA has not revealed what it paid but, Mr. Robison says, "it was very clear to all of us, including the trustees, that this was a great opportunity."
Such purchases have given the National Gallery a preeminence in works on paper collections outside of Europe — and sometimes even including Europe. For example, the NGA has more than 3,000 pieces by Piranesi, whose collection of Rome views (Vedute) were the sought-after picture postcards of their time for wealthy travelers on what was known as the Grand Tour to Italy.
"What we've done with the Augsburg show has astonished even some German friends because we've been able to mount it almost entirely out of our own resources, having built up the collection over the course of time," says Mr. Robison. "In fact, the general director of all the museums in Augsburg wanted to borrow the exhibition — for Augsburg. But we already have three venues planned."