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With Chemistry And Care, Conservators Keep Masterpieces Looking Their Best

Senior conservator of paintings Ann Hoenigswald works to fill in elements of Paul Cézanne's <em>Riverbank</em> c. 1895 in the National Gallery of Art's Paintings Conservation Lab in Washington, D.C.
Liam James Doyle
Senior conservator of paintings Ann Hoenigswald works to fill in elements of Paul Cézanne's Riverbank c. 1895 in the National Gallery of Art's Paintings Conservation Lab in Washington, D.C.

Behind the scenes at major art museums, conservators are hard at work, keeping masterpieces looking their best. Their methods are meticulous — and sometimes surprising.

The painting conservation studio at the National Gallery of Art in Washington, D.C., is filled with priceless works sitting on row after row of tall wooden easels, or lying on big, white-topped worktables.

The studio is where I first met Senior Conservator Ann Hoenigswald years ago as she was fixing the sky on one of Claude Monet's impressions of the Rouen Cathedral in France. Bits of paint had flaked off over time, and Hoenigswald was carefully mixing her blue to match the old master's. Seeing the painting outside of its fancy frame, it felt like being inside the artist's studio. (I greatly wanted to try my hand at filling in some tiny bare spot in Monet's sky, which had once been covered by paint. Of course, the thoroughly professional Hoenigswald politely refused to hand over her brush.)

Conservators must take classes in studio art, art history and chemistry. Sometimes guidance comes from artists themselves. For example, Vincent van Gogh wrote to his brother Theo, asking for specific shades of paint — Prussian Blue, Ultramarine, Geranium Lake. Painters in earlier centuries rarely left such clues.

Conservator Michael Swicklik peers through thick lenses that give him a 3-D view of a 15th-century canvas that Italian Renaissance artist Fra Angelico may have painted. They can't be sure, because The Entombment of Christ is in awful condition — freckled with pocks where paint flecked off, and the gold on the saint's halo has worn away. The entire surface is dulled from varnish that's aged to the color of caramels.

Swicklik gets to work with cotton, solvent mixture and a bamboo stick. (Sometimes they just use spit, which gets grime off nicely!) He focuses in on the caramel-colored varnish obscuring the saint's robe — moving over the surface in very light circles, to avoid abrading the paint.

Varnish is the enemy here. Painters, dealers or buyers often put a clear coat of it on to preserve a painting, or give it a nice sheen. Jay Krueger, Head of Painting Conservation, says over time the varnish ages and actually changes the colors of the painting.

"You remember that sky being blue and it's kind of green now, or, you'd remember that this was a lovely silvery dress and it's yellow now," he says. "It's just a matter of that surface, that transparent layer, discoloring over time. So it'll turn reds more orange, it'll turn blues kind of greenish. It darkens the light colors and, in an odd way, it flattens out and lightens the dark colors."

There are all sorts of chemicals involved in the quest to remove the offending varnish, so big blue vacuum tubes — they look like elephant trunks — hang from the ceiling, sucking up fumes and smells.

"You don't want a 40-year career cut short because you're in a room full of open solvents," Krueger says.

The solvents are tailored to meet the needs of a particular painting. Conservator Joanna Dunn is wearing blue rubber gloves to protect her hands from the strong solvent she's working with. Looking through a very fancy microscope, she bends over a 16th-century Tintoretto called Summer. The big canvas — it's more than 3'x6' — shows a zaftig blonde, reclining in a field, her right breast peeking out from her pretty pink drape. For some reason, a parrot turns his back on her. Armed with cotton swab, skinny stick, solvent and a scalpel, Dunn goes after the usual suspect: Varnish.

Joanna Dunn works to restore Jacopo Tintoretto's <em>Summer</em>, c. 1555. The blue vacuums suspended from the ceiling assist with ventilation.
Liam James Doyle / NPR
Joanna Dunn works to restore Jacopo Tintoretto's Summer, c. 1555. The blue vacuums suspended from the ceiling assist with ventilation.

"This coating is so old I can't dissolve it without harming the paint," Dunn explains. "So the way to do it is to soften it with the chemicals that I'm using, and then ... it becomes gelatinous and I can push it off with the scalpel."

She does this all verrrrrrry carefully. At some point she'll put down the scalpel, pick up a paintbrush and fill in any spots that are missing paint.

"I'm only going to put my inpainting in the area where the paint is missing," she says. "I'm not going to cover any of the original paint."

In addition to varnish, conservators also need to get rid of paint that was applied in earlier restorations and then replace it with colors that match sometimes centuries-old originals. They hope to leave these canvases in better shape so that future conservators have an easier time of it when their turn comes.

Every day, these conservators hop between centuries and styles to preserve masterpieces for future art-lovers. A few years ago, Hoenigswald had a 19th-century Mary Cassatt on one easel, and a 16th-century El Greco on another — and they almost seemed to be in conversation with each other.

Mary Cassatt was a great admirer of El Greco's work, Hoenigswald explains: "I was practically in tears thinking: Oh my god, if she ever thought she'd literally be side by side ... it was a very emotional."

Moments like these, she says, can make these behind-the-scenes conservation studios feel downright magical.

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The National Gallery of Art in Washington, D.C.
Liam James Doyle / NPR
The National Gallery of Art in Washington, D.C.

Nationally renowned broadcast journalist Susan Stamberg is a special correspondent for NPR.