Housekeeping: The Thinker

Geneva Griswold, the former Andrew W. Mellon Fellow in Objects Conservation, talked with us about how she and her colleagues keep Auguste Rodin’s sculpture The Thinker looking its very best. 

Photo by FAMSF

How often does The Thinker get a good scrub?

The last time was about four years ago. During maintenance we apply a wax coating, and every year we assess the surface to see if we should re-apply or adjust the coating. We’re always monitoring this sculpture so we know if there are significant problems. Ideally, by waxing a sculpture annually you create a surface that’s very easily cleaned and maintained.

Ideally, by waxing a sculpture annually you create a surface that’s very easily cleaned and maintained.

Photo by FAMSF

What kind of products are under your (metaphorical) sink?

First we use a cleaning product called Sulfonic to wash the sculpture twice with sponges to remove the general grime and then dry with towels. Sulfonic is a non-ionic detergent, and it has no colorants, no additives, and nothing else that will stick around on the metal.

Then we gently heat the surface of the metal with a propane torch to identify where the old wax remains. We heat the sculpture very slowly, area by area, starting at the bottom to avoid shocking the metal. Heating the sculpture gets it ready to receive the layer of fresh wax.

The wax we use is a mixture of microcrystalline wax called Polywax 2000. We can pre-tint the product by adding a pigment, or add a solvent to make it just soft enough to dip a brush in. In this case it was a 10%-90% combination of waxes, one harder and one a little softer, to get the right consistency. The harder the wax the more durable it will be, and the softer the wax the easier it is to apply.

We apply the wax with bristle brushes, and then buff it with rags, getting softer and softer, until finally you use nylon pantyhose to buff it to a sheen. You're basically pushing wax into the metal's pores.

With The Thinker, you can see his big toe is bright and shiny because people rub the wax and the patina off.

Photo by FAMSF

Where are the trouble spots?

When the bronze is blazing hot, getting into the armpit or the back of the leg is tough. Removing the wax in those crevices is really difficult.

With The Thinker, you can see his big toe is bright and shiny because people rub the wax and the patina off. That’s an area that we need to come back to and address continuously. It’s also an aesthetic issue--it looks like he’s stubbed his toe!

How does the sculpture get dirty?

At the Legion of Honor it’s primarily the proximity to the ocean, in addition to pollution like car and boat exhaust and organic material like leaves. Salt is the number one thing that corrodes metals, so you want to make sure you have every centimeter of the sculpture covered. There’s salt in the air, and the low fog makes the water condense which could lead to corrosion.

Photo by FAMSF

Do you have any cleaning secrets?

In terms of choice of the coating, you need to understand what patina the artist intended. For example, was it brown, black, or bright turquoise; was the tone even or more mottled? Knowing that helps us to choose what wax to put on and helps us even out the tone.

When do you know your work is done?

You want to achieve an overall even coat with the wax and then polish the surface until you get a smooth, glossy appearance. It almost gets to the point where you don’t see the wax, but you get a glowing, saturated surface.

Tracy Power, owner of Tracy Power Objects Conservation, was the head of the project, assisted by Geneva Griswold and conservator Teresa Millas. The project was overseen by Lesley Bone, Head Objects Conservator at FAMSF.

Housekeeping is a series in which we ask our conservators to tell us more about the behind-the-scenes tasks that are part of maintaining the Museums’ collections.