How Art Conservators Clean Paintings?

When the Rijksmuseum in Amsterdam disclosed its intention to begin restoration work on Rembrandt's The Night Watch in July 2019, it garnered international attention. This masterpiece has been restored previously. However, what sets this occasion apart? This time, art enthusiasts will have the unique opportunity to witness the restoration process firsthand, as it will be conducted openly within the museum for the public to see!

This project is expected to cost millions of euros and will take years to be completed. For connoisseurs the world over, it is exciting to be able to see a work of art up close and personal, at its most vulnerable. It gives them the feeling of being close to the art and the artist.

The Night Watch by Rembrandt

The Vagaries of Time

Fun fact, Night Watch is not the original name of the painting. It was not painted as a night scene! Over the years, it had accumulated so much dust that it seemed to be depicting a night scene.

Paintings are cultural emblems that narrate the story of mankind and its evolution. However, the rigors of time leave their sordid effects on these works of art. Paintings age; they start looking old and faded because of dirt. The surface of a painting can be damaged by water and mildew as well. Sometimes, the extent of the accumulated dust and grime is such that the original work is not visible at all.

A painting undergoes a lot of wear and tear not only at the front, but at the back, and between the fabric and the frame as well. Besides, incidents of vandalism also leave their mark on them. These exquisite pieces of art need to be conserved, and, in some cases, restored to their original grandeur.

The Resurrection of Lazarus by Caravaggio

Caravaggio’s The Resurrection of Lazarus is another masterpiece that has had to undergo the painstaking process of restoration. The painting had been restored multiple times, and repeated applications of varnish had made it turn yellow over this period. When this piece was handed over to the team of conservators, they had to use solvents to dissolve the varnish. The thick yellow layer had till then totally obscured the beauty of this spectacular masterpiece.

How Art Conservators Clean Paintings 2

The Ressurection of Lazarus

Conserving Art for Posterity

Art conservation involves cleaning as well as restoring the painting to its former glory. Cleaning is one of the most demanding aspects of art conservation. Conservators need to have years of training and experience before they can get to work on restoring great works of art. An art conservator needs a thorough understanding of art, history, and chemical materials.

Water-soluble materials that have been used in a painting tend to absorb water and moisture like a sponge. The paint fibers swell up and cause tension on the overlying paint, causing it to flake off. If water is used to clean such a painting, the paints might get washed out, causing irreversible damage. Conservators need to know how water and solvents react with paint materials before deciding on proper cleaning methods.

Getting to Know the Painting

Experts in conservation try to devise the least invasive method for cleaning to retain the originality of the work. In the initial analysis, conservators study about the paints, pigments, and fabrics used in that era. Much like a doctor, they scan the entire surface of the painting using X-ray technology to study variations in paint texture. Seems scientific, doesn’t it? Well, there’s more.

To assess any paint loss, conservators use infrared imaging and cameras with fixed wavelengths on every bit of the painting’s surface. Spectroscopy is used to replicate the composition of the original paint. This is so that any cleaning routine can be tried on a replica of the paint material before using it on the original piece.

The Cleaning Process

The simplest way is to clean dirt off painting is by brushing and vacuuming. Water-based systems are very effective at dirt removal. However, these cannot be used for all types of paintings. Aqueous solutions in the gelled form are more effective since the cleaning solution and the surface can be kept in contact for a longer time. Detergents and chelating agents are equally effective at washing off the dirt on paintings.

Once the original varnish is cleaned off with solvents, a new coat of non-yellowing varnish is applied to the painting. This helps keep the original work intact and any retouching can be applied over the varnish. Amazing, isn’t it? To paint over the lost parts of the painting, dry pigment with non-yellowing solvents is used.


The Night Watch has been vandalized three times; even after repeated restoration effort, the knife marks are still visible. The marks left on these masterpieces over time are like the wrinkles on the face of an old woman. They tell stories of a life well-lived and much-traveled. Whether it is an oil painting or a watercolor, go ahead and buy them and add some art history to your collection. Protection Status
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