Art conservation is a union of science and art. Here's the process behind restoring a 125-year-old painting.

Restoring a piece of art goes beyond just freshening up the work of art. Part of the process is making sure that it can be restored again in the future.

"I think every time you treat an object, there is risk involved," Narayan Khandekar, director of the Straus Center for Conservation, said. "And so what you want to do is when you treat it, you are reducing the risk in the future."

"You do it hundreds of times you get used to it," Drew said. "Initially, it's definitely scary, but you just get more confident the more you do it."

Using pliers to remove the painting from the frame allows the canvas to come out and be restored without hindrance. While the painting is restored, another person works on restoring the frame.

The edges of the canvas stay bent from decades of being stuck in the same position. Drew cuts silicone release paper, puts it on the rigid edges, and presses them with an iron. This process releases the folds and flattens the canvas. 

After the vacuum, Drew will wipe the canvas with a vulcanized sponge to remove what the vacuum could not pick up. 

The sponges are specially made for conservation work and are more porous than normal sponges, according to Drew. This way, the sponges can pick up dirt and debris that may be more ingrained in the canvas.

Drew said some of the paintings that come into Center Art Studios come from social clubs in New York. The artwork that came from places like these can sometimes be in a public setting for decades and be exposed to smoke and tobacco that accumulate on the surface of the painting.

The initial surfactant cleaning is to take away the surface impurities before any of the varnish or paint below is impacted. The cleaning is done using cotton swabs in small circular motions over the whole painting.  

Restoring a painting isn't just working with clues left by the original painter, but also the decisions and mistakes of past conservators. 

According to Drew, industry practice now involves detailed notes of the materials and techniques used to restore a piece. The hope is that these notes will stay with the painting into its new life for years to come. 

Often, Drew and other conservators are not as lucky and run into inexplicable decisions made by past conservators. Sometimes it is a faulty repair, like in the painting Drew is working on, or sometimes the material simply ages poorly.

"[People] would use materials that would change differently from the original materials because they weren't thinking about reversibility, they could be quite difficult to remove," Khandekar said. "Now,  we want to use things that stay soluble that can be easily taken off without damaging or changing the original material."

The blacklight is one of many ways to learn about the underlayer of a painting. Conservators put varnish on a painting as a protective coat, which can enhance certain elements of the painting itself. 

Understanding what lies underneath by using a blacklight helps conservators develop new approaches to strip the varnish and begin the restoration process. 

The 24-person lab at the Harvard Art Museum uses a variety of tools to develop a better understanding of the artwork. One machine — the Fourier Transform Infrared Spectrometer — uses small diamonds and rays of infrared to examine what materials have been used, as well as determine what materials should be used in the future.

Drew works in small discreet areas on the surface of the painting with various combinations of solvents. Using the blacklight, she can see whether or not her approaches are working. 

"You start off with something you're pretty sure won't work," Khandekar said.

From the smallest point, conservators work their way up to stronger solutions until they find the right combination. If the test cleaning window reflects back purple, Drew has successfully cut through the varnish and can proceed. 

"I save the face for last in this instance, mostly because it's the most dramatic part of the cleaning process," Drew said. "And it's good motivation to keep going, we want to get to the face."

The patches on the painting are left behind from past restoration jobs. During a restoration job, patches are added to hide or repair rips in the canvas.

In this instance, the old patches are replaced for the same purpose. New patches of linen are adhered to hide holes and repair rips in the surface of the canvas. 

The middle of each side of the new strip lining and the original stretcher are marked. Once marked, the painting is lined up and tacked back into the stretcher using a tacking hammer.

The isolation varnish works as a barrier between the original paint and whatever new paint will be put onto the painting to restore it. 

The varnish being used is a "reversible, non-yellowing, conservators varnish that is easily removable," Drew said. 

According to Drew, a common misconception is that the original material is used to restore a painting or piece of art.

Drew uses paints that are specially made for conservation and can be removed easily. If a mistake is made or the wrong color is chosen, it can be easily removed without affecting the original paint underneath.

For instance, using oil paint to restore oil painting would result in chipping and flaking. Instead, there are specialty paints like B-72 acrylic that are easily re-soluble and removable, Khandekar said.

While the molds are fitted and shaped to the edges, the rest of the frame is cleaned and cracks are filled in with the same water-based putty.

The frame is retouched and shellacked to preserve the restoration. 

Restoring a painting is no quick and easy process. A common misconception people have when they come to Center Art Studio is how much time it will take. But the process can be as satisfying for the owners of the paintings as it is for the conservators. 

"You have to sort of be thinking of new solutions to problems that pop up, so that's fun. That kind of keeps you on your toes," Drew said. "I also just love the different parts of the process, especially of cleaning a painting ... it's like you're revealing a beautiful image underneath that's been obscured for decades."