Conservation offers one of the most intimate views into the artwork–not only into the technical process but into the mind of the artist. Since one of the jobs of the conservator, amongst others, is to physically touch a work of art, to remove dirt, extract stains and reduce previous overpaint from its surface, or to minimize scratches and repair tears and cracks, their judgment and treatment can be consequential. 

The first step therefore is to get to know the work, its history, and the history of previous conservation interventions, if this has been the case. Depending on the condition and the nature of the issue, measures are taken to bring the work into a healthy condition and as close to the state it was in when the work was originally completed. In general, the goal is to present the work in an authentic condition, while acknowledging its history and age. The principle here is: as much as needed, as little as possible.

Initially, examining and assessing the condition of the work. A conservation response might be required if there are any unstable aspects to the work, however, it is also possible that damage or changes in the work have created an aesthetic consideration. Typically, the conservator would urge any stabilization treatment that might be necessary to limit or prevent loss of original material. The treatment of aesthetic issues would be made in concert with the conservator and owner/agent for the painting in keeping with the artist’s intent. Additionally, conservation may encompass long-term environmental suggestions and planning for safe stewardship.

Conservators are not only concerned with conservation treatment, but also with preservation. Preservation entails maintenance such as checking the environmental climate levels (the average for paintings is 68-72 degrees F / 55 - 60 % relative humidity (RH)), the light levels (no direct sunlight), as well as a proper space for installation, e.g. no delicate artworks in narrow entrance ways.

It may be the case that the paint is lifting from the canvas without anyone noticing it. Or parts of the painting have been inpainted or otherwise restored. Inpainting or touch-ups can often only be determined by the use of a UV examination lamp.

We would recommend that a painting be examined by a conservator. A base-line condition report for the painting, identifying any potential concerns would be created, and that would function as a basis for comparison over time when the work is periodically re-examined.

It’s a bit of a language game. In the UK, our profession is called ‘conservator-restorer’, in German it is named ‘Restaurator’. In the US, the general distinction is that the aim of the restorer is to return an artifact to its former or original perfect state, whereas the approach of the conservator is to preserve not only the physical object but also respect and ensure the historicity, and its signs of age.

Another way to describe the difference in treatment is that conservation is concerned with everything: from preservation over cleaning and securing the physical substance of an object, without introducing any new material to the object, e. g. inpainting paint losses, to replacing impaired or missing parts in sculptures or installations. Restoration, however, includes the completion of an object to an unimpaired or perfect condition.  

Traditionally, colorfield paintings or monochrome surfaced are very hard to restore. Imagine the rubbing of a dark leather handbag against a monochrome painted surface, or a fingerprint on a ‘Monochrome Bleu’  painting by Yves Klein. Once the colorfield is interrupted, the aesthetic illusion of space is gone and the attention is caught in the imperfection. It has happened that a visitor in a museum had to sneeze in front of a multi-million matte monochrome Ad Reinhardt painting–a total loss for the insurance. A puppy dog recently chewed on a wooden sculpture by a famous minimal artist and a forklift in an airfreight hangar punctured two paintings in a shipping crate on loan to a museum. 

It is not so much a matter of what the material or medium might be but more related to the way in which the materials have been used, the intention of the artist, and the overarching aesthetic of the work.

That really depends on the nature of the artwork and issue at hand. Conservation and restoration include detailed word- and image documentation, before and after treatment, often with multiple tests for the use of solvents or other applications usually executed on specifically constructed dummies. Conservation treatment can last from one day to multiple months or years–often longer than it took to make the work in the first place. 

This question touches on the broader question of: who makes the decision on restoring the work, and what are these decisions based on? It is usually the owner who makes the decision of whether to restore a work of art, often based on the value. The conservator, however, then makes the decision about what needs to be done to the work. Sometimes the artist is involved in this decision, but their imperative role is limited due to the Visual Artists Right Act (VARA).

It may be inadvisable to treat or intervene in a work of art if that intervention would be counter to the artist’s intention and/or aesthetic.

In historical works, the material (canvas, wood, oil paint etc.) are implemented by the artist to represent an image–a landscape, personage, a bowl of fruits–while in contemporary art the material IS the image. 

Instead of painting the fruit of a lemon, an actual lemon becomes part of the work. This in itself is a challenge in contemporary art, to deal with organic matter (fruits, chocolate, elephant dung, donuts etc.).

In Joseph Beuys’ last multiple Capri Battery (1986), for instance, an electrical socket with a yellow lightbulb is plugged into an actual lemon. Here, the lemon is used for its inherent natural acidity, which in combination with the copper in the electrical socket can produce energy (physically and metaphorically). According to the artist, the lemon (battery) has to be replaced after 1000 hours (approx. six weeks). This signifies that contemporary art often needs permanent maintenance, which poses a problem in many museum institutions.

I think one of the biggest developments in conservation has been the introduction of gels and other and ph-modified applications for cleaning delicate surfaces. Instead of physically removing dirt and grime using swabs or sponges, the foreign material (stains, dirt, fingerprints etc.) will be extracted in a capillary reaction. 

Like other fields, conservation benefits from research and advancements made in all material science and aesthetic areas of study. A good example are the huge strides made in the cleaning of acrylic paint films, previously not fully understood. Some of the significant advances in conservation are the direct result of progress in analytical imaging, and in the food, drug, and cosmetic industries alongside research and materials developed for the needs of electronic engineering.