If you ever catch sight of museum staff applying their saliva to a world-famous painting, don't be too surprised—it's actually a highly effective method for cleaning artworks.
Staff are cleaning an oil painting.
The Ig Nobel Prize in Chemistry for 2018 was awarded to a study from 1990:
Human saliva is an effective cleaning agent. In fact, this cleaning method is quite ancient, possibly with a history of thousands of years, and today saliva remains one of the most convenient and effective cleaners for some art museum curators.
Saliva contains various enzymes, such as amylase, lipase, and lysozyme, which can partially digest food entering the mouth and break down food debris between teeth, also exhibiting antibacterial properties.
Therefore, saliva can also clean dust, dirt, and other foreign substances on paintings. Some believe that saliva, with its slight warmth and weak acidity, is particularly effective in removing dirt. Sometimes, calling it "spit" can make some people uncomfortable, so it is also referred to as a "gentle enzymatic solution."
However, when using saliva to clean paintings, some saliva tests must be performed on the artwork, testing whether the materials used in creating the artwork dissolve in water in inconspicuous areas and corners.
Then, several cleaning agents, such as saliva, water, and others, are compared to determine which one is most effective in removing dirt before actually using saliva for cleaning.
In an art museum in the United States, conservators used saliva to clean a painting, leather items, and a saddle.
The restoration process simply involves using cotton swabs dipped in one's own saliva to clean objects, without the need for ventilation like other cleaning agents. Conservators also noted that while some may find it a bit gross, after cleaning in this manner, "we further clean the surface of the painting and keep it dry for a long time."
Source: Reference 6
Katrin Radermacher, a painting conservator at the Kunsthalle Mannheim in Germany, mentioned that in the past, various materials were used to restore artworks, such as milk, beer, vinegar, turpentine, and even sand, but none of these are recommended materials.
Today, some surface-active agents used for cleaning have excessively high concentrations. Therefore, the most appropriate solution she ultimately chose was artificial saliva and distilled water.
A painting cleaned with saliva, with the removed dirt depicted above.｜Reference 4
However, in 2020, the once-considered hygienic practice of cleaning with saliva was no longer recommended. Dental experts at the University of Queensland in Australia suggested that during pandemics, saliva might harbor bacteria and viruses, contributing to disease transmission. Therefore, the practice of saliva cleaning also needed to be reconsidered.
The entire saddle is cleaned of stains using saliva.
Hence, due to safety and health concerns, local museums in Australia no longer employ this cleaning method, with experts suggesting the use of artificial saliva in the future.
