October 12, 2023

Sofia McGrath

10th Grade

The Young Women's Leadership School of Queens

Science is involved in numerous aspects of our day-to-day lives. Even seemingly simple processes that may be overlooked can have intriguing scientific explanations backing them, including paint varnish. What is paint varnish and what does it have to do with science? Varnish is a relatively transparent liquid coating composed of either synthetic or natural solutions. It primarily serves as a protective layer on a painting, enhancing the final product's overall aesthetic through the intensification of its pigments. Science plays a significant and fascinating role in how varnish affects a painting, the properties of varnish, and how it changes over time. 

Paint Varnish has been in existence for centuries. Initially, the accepted idea was that John Wykc invented varnish following his distinctive and realistic oil paintings. After this idea was disproven, a new idea arose that the practice of varnishing began during the Medieval art period of the material mimesis. In his article, Marijolijn Bol describes how artisans embellished wood and metalwork using varnish and glaze to imitate gold and precious metals. Similarly, Medieval panel artists used this technique to produce a look mimicking that of materials such as enamel, silk, and so on. 

Throughout time, resourceability and an evolving art style allowed for a variety of materials to be used for varnish– in actuality, by the time of the early Renaissance, materials such as egg white, resin, insect secretions, and fossil and tree resins were used. Despite a decline in usage during the 19th century, varnish has continued to be used today by artists and restorers. The ability of people in history to create and use varnish came from their understanding of scientific properties such as refraction and reflection, which were essential in the creation of varnish. 

  There are two broad categories for varnish: synthetic and natural varnish, which have a few key differences. Natural varnishes are made of animal and plant material. They are vulnerable to deterioration when exposed to the environment, which may result in a loss of transparency, yellow discoloration, and cracking. Therefore, many artists and conservators have to replace them over time. Natural varnishes tend to have a low molecular weight, thus solving low viscosity. According to the Natural Gallery of Art, due to these properties, it produces a higher saturated and glossier result than synthetic resin. On the contrary, synthetic varnishes which were first created by Leo Baekland are made out of petrochemicals (chemicals obtained from natural gas). They are more stable and can be manufactured in large quantities and are therefore more widely available. Thus the question arises: why are they more stable, yet, may lack the same quality of saturation and depth as that of natural varnish? This is due to science. Unlike natural varnishes, synthetic varnishes are produced through polymerization. Polymerization is the process in which small molecules chemically combine to form a large chainlike or network molecule. Due to this process, polymeric resins tend to be more stable than natural resins. Nevertheless, they produce viscous solutions even at low resin concentrations, resulting in a high-viscosity solution and a greater molecular weight. This high viscosity and molecular weight cause lower saturation in the varnish.

As time persists, varnish continues to develop and advance, as well as our understanding of the scientific processes involved in varnish making. As a result of acquiring more scientific knowledge, properties of varnish such as flexibility, durability, gloss, and protective ability can be improved upon and more easily manipulated, giving artists, conservators, and/or the general public additional options for varnishes.