The Science of Art Restoration

Over the lockdown, there was a niche craze on the internet that I came across - people were spending hours watching Baumgartner Restoration’s YouTube channel. Imagine a work of art painted during the renaissance era, maybe something depicting Mary, Mother of Jesus. A curator gets hold of this work, and offers the assessment: Medium: oil on wood, condition: severe craquelure with visible gaps on the paint surface [Translation: it’s flaking, cracked, and looks beyond saving, as very old paintings tend to be]. And yet, through some miraculous divine intervention by the hands of an art restorer, the painting of Mary returns to market, in a far better shape and valued in the tens of thousands…so how does this all work?

The image that immediately pops into our head is that of a person hunched over a canvas, brush in hand, delicately touching up a masterpiece. But the reality of restoration is far more dynamic and, dare I say, a real work in progress. Restoring art is a process filled with collaboration, scientific knowledge, artistic precision, problem-solving, and so much time.

The Inevitable Decay of Art

No artwork is immune to time. The materials used—whether wood, textile, canvas, or stone—each deteriorate in their own way. Even within categories of material there’s a spectrum; there are better quality paints for example that are able to stand the test of time better. 

Organic materials are vulnerable to moisture and pests; paintings fade, crack, or warp due to fluctuating temperatures and light exposure. If you've browsed our marketplace, you may have come across the term "foxing", it refers to the brown spots that appear on aged paper due to oxidation. Even murals suffer water damage when walls absorb too much humidity.

Lo Manthang, a historic walled city in Nepal's Mustang district, has been the focus of significant art restoration efforts. The city's ancient monasteries and temples, adorned with intricate murals and artifacts, suffered from centuries of neglect and environmental damage. Roof leaks and crumbling walls have been affecting stunning murals created by monks that speak of years and years of history, some even pre-dating the written word. In recent years, international teams of conservators have undertaken the meticulous task of preserving these cultural treasures. 

Their work involves cleaning and stabilising delicate paintings, repairing structural damages, and training local artisans in conservation techniques to ensure the sustainability of these efforts. In the traditionally male-centric Buddhist society of Lo Manthang, Nepal, art restoration projects have provided unprecedented opportunities for women to engage in cultural preservation. It was during the restoration of the 15th-century Thupchen Monastery, the American Himalayan Foundation initiated a program that trained local community members in conservation techniques. This initiative was inclusive, allowing both men and women to participate. As a result, women in Lo Manthang began to take on active roles in the restoration process, contributing to the preservation of their cultural heritage. 

Art restoration techniques are ever-changing, and in the case of these monasteries, restoration may require blending ancient techniques with modern understanding. And history has shown the consequences of poor restoration techniques. Back in the 19th century, restoration techniques involved covering entire paintings in wood-ash, then wiping it off with water. 

This resulted in the formation of an extremely alkaline substance which was harmful to the painting. Today’s restorers are far more knowledgeable and equipped, and I’m glad to contribute to their progress as I waste away watching their content on YouTube.

And so it begins…

I want to start by correcting a general misconception. Restoring an artwork is not about making it look new—it’s about stabilising the artwork whilst respecting its original integrity. 

Let me break this down. The process begins with a thorough examination, where conservators analyze the medium, pinpoint causes of deterioration, and determine the best course of action. It’s a thorough process requiring knowledge about chemistry, material science and physics.

Part of the first steps in conservation is imaging the artwork using X-rays, ultraviolet (UV) light, and infrared reflectography. These tools allow conservators to see beneath the surface, revealing underlying sketches, hidden layers of paint, and areas of past damage. This step is crucial, guiding conservators on how to proceed without causing further harm.

Art restorers go about their practice with the guidance of the principle of reversibility, meaning that any interventions can be undone without harm. Meaning that as conservators work, they ensure that they are able to trace back to the exact original brushwork of the work. This procedure was what caused the famed restoration of Da Vinci’s the Last Supper [1] to last 20 years. 

Cleaning and Stabilising the Artwork

Once the process is mapped out, the actual restoration begins—often with a painstaking cleaning process. Because works of art are intricate, the accretion of dirt and grime requires a great amount of careful consideration while cleaning so as to prevent damaging the work. Where artists are afforded the luxury of erasers and layers, the finished art does not give the conservator the same amount of grace.

The layer of varnish artists often use, ironically as a means of protecting the artwork, causes an additional problem for the restoration. As varnishes are chemically different from the material of the art as well as the pigment, conservators have to meticulously pick out the solvents to be used so as to not damage the artwork. Even the slightest mistake can cause irreversible damage, which means there’s literally no room for error. 

Piecing them all back together

After dealing with surface accretion, the artwork must be carefully stabilised before restoration can proceed. In the case of a painting, this means meticulously reassembling each flake of paint, ensuring every fragment aligns perfectly with the rest. In some instances, gentle heat may be applied to help the pieces bond, but this requires precise control and an in-depth understanding of the materials involved.

Physical damage caused by natural elements—such as UV exposure, water damage, or paint loss—must be addressed through specialised techniques tailored to the specific artwork. Often the piece is removed from its original frame and mounted onto a more stable stretcher to preserve its structural integrity throughout the restoration process.

Reintegrating Lost Details

Only at this stage does the conservator actually pick up their brush.

Inpainting is where artistry meets science most directly. Missing areas of paint must be colour-matched with extreme precision, using pigments that will remain chemically stable over time. Restorers also mimic the artist’s brushwork to maintain authenticity. However, in keeping with the principle of reversibility, these new additions are done in a way that allows them to be distinguished under UV light, ensuring future conservators are able to differentiate between the original and restored sections. This is so that future conservators can remove old restoration work so as to apply any better future techniques/solutions on the artwork.

All of this to say that a vast amount of comprehension and knowledge is required on the restorer’s part–different techniques, as well as different styles of art, in all the infinite forms that it takes. Restoration is not about altering art; it is about safeguarding the stories and techniques of the past, ensuring they continue to be seen, studied, and appreciated.

The Intersection of Art and Science

Through the intersection of art and science, we do not merely restore paintings—we restore history itself. Every careful brushstroke, chemical analysis, and structural repair is a step toward ensuring that future generations can experience the artistry and craftsmanship of the past. In a world where time inevitably wears away even our most treasured creations, art restoration stands as a testament to our dedication to preservation—not just of objects, but of the stories they tell and the legacies they hold.

Written by Fithriah Hashim

[1] - the story of the 20 year long restoration of the Last Supper is not without controversy. It has sparked the question: at what point in restoration does an artwork stop becoming an original?