The Chemistry of Art Preservation

Introduction

YouTube Video

The chemistry of art preservation is a very complex project. Nevermind the extent of artifacts that conservation applies to; ancient pottery, furniture centuries old, even hieroglyphics need to be preserved! I focused my project solely on oil or acrylic paintings.  There are many procedures a preservation scientist can choose from, such as organic solvents and responsive gels for cleaning pieces and several techniques for actually restoring the paint on pieces. Museums and history have always fascinated me, so I combined the two to learn about how conservation saves old pieces. How is life affected by the saving older pieces for our prodigy to enjoy? It is for the simple reason that I can walk into the Louvre and see Leonardo Da Vinci’s work with my own eyes. And thanks to the science behind conservation of art, your children can too.    


Composition of ...
  • Organic Solvents

    • Different compounds of hydrogen, oxygen, and carbon

  • Lead-white paint

    • A toxic white paint

    • 2PbCO3-Pb(OH)2

  • Methyl Cellulose

    • An adhesive

    • C6H7O2(OH)x(OCH3)y

  • Polyester Terephthalate Film

    • Resin used in synthetic fibers

    • C10H8O4


Main Chemicals, Compounds, Components

  • Multispectral Analysis

    • Infrared radiation to ultraviolet fluorescence

    • Multispectral Analysis is a portable device that allows researchers to analyze works of art without damaging the pieces by moving them into a lab. Using a range between infrared radiation to ultraviolet fluorescence light, multispectral analysis allows conservationists to see writing that was too damaged to be seen with the human eye, take stock of pigments with out a sample from the physical painting, and  helps identify forgeries by studying techniques and technology of the time.

  • Synthetic Resin

    • C10H8O4

    • Synthetic resins protect the original piece from the humidity, light, and dust it is subject to on a day to day basis. Thanks to the molecular weight of synthetic resin, the development of paint for touch ups on the paintings has made leaps and bounds.

  • Natural Resin

    • A hydrocarbon secretion from plants

    • Natural resins are very similar to synthetic resins, the main difference being natural resins are most authentic for oil paintings. They also darken the colors of paintings. Natural resins do decay over time.


Chemistry's Role

Chemistry is a double-edged sword and it cuts both ways in the art world. Due to many chemical reactions with older oil paints and the even the canvases they were painted on, the art pieces deteriorate. Fading colors cause the art to look completely different from the original. But chemistry has also increased the development of better tools for preserving and conserving art than ever before. A plethora of synthetic resins have been designed to enhance color, create the gloss similar to the original natural resin. Just like natural resins, synthetic resins have a low viscosity and molecular weight. But synthetic resins have the upper hand; they are soluble with less harsher solvents which means they damage the painting less when they are removed.

Chemistry had also allow us to go back through time. Multispectral and x-ray analysis have been designed to show minute details in the art, even the artist’s fingerprints! Thanks to the light spectrum, we can see the technique and technology of the time, as well as what chemicals have been used in previous conservation attempts. Chemistry plays the most important role in art preservation (both as the antagonist and the hero), save for the art piece itself.


Background Research

Natural resin is a collected plant secretion of hydrocarbon. It is placed over the painting to protect it as well as add a gloss to the painting and darken the pigmentation. Synthetic resin act similarly to the natural resin are more soluble. They are designed in a lab and used in conservation labs in museums and with private investors. Multispectral Analysis is a portable device that allows researchers to analyze works of art without damaging the pieces by moving them into a lab. Using a range between infrared radiation to ultraviolet fluorescence light, multispectral analysis allows conservationists to see writing that was too damaged to be seen with the human eye, take stock of pigments with out a sample from the physical painting, and  helps identify forgeries by studying techniques and technology of the time.


Resources

  • Smithsonian Museum Conservation Institution

  • http://www.si.edu/MCI/english/learn_more/taking_care/

    • Taking Care of the Painting

      • Made up of: support, ground, paint, and coating

      • Fabric or wooden panel

      • Ground- smooth surface and absorbs excess binding media of the paint

      • Layers of paint

      • Coating- protects painting from dirt and moisture

        • Synthetic or natural resins

    • Displaying Paintings

      • Dirt & Heat

        • Heat dries up the materials of the painting and acts as a catalyst in the natural aging process

        • Heat softens paint

        • Heat rises and brings grit and dirt with it

      • Water & Moisture

        • Weakens paint adhesive

        • Especially bad for the support and ground

      • Humidity

        • Low Relative Humidity

          • Minimizes chemical change

          • Makes paint brittle and increases the possibility of mechanical damage

        • High Relative Humidity

          • Minimizes mechanical damage

          • Prone to the growth of biological organisms

          • Mold growth (often black spots) especially prone to acrylic paintings

        • Change in Relative Humidity

          • Wooden panel slowly concaves

      • Light

        • Fugitive dyes and colorants (in the paint) eventually discolor under UV light.

        • The wavelengths and intensities of light used in displaying graphic art are okay for paintings

  • The Painting Guide

  • http://homepages.ius.edu/dclem/ptgguide/ptggd10.htm

    • Ground- The first layer of the painting that serves as a barrier between the canvas and the painting

      • Used on canvas, while gesso used on supports

      • Can be textured or in a multiple of colors

      • Acrylic grounds

    • Gesso- mixtures of smooth and coarse plasters applied in layers

      • Then- gesso/gypsum was applied to rabbit skin to make gesso sotile (soft) for panel paintings

      • Now- blend of white chalk and polymer emulsion for acrylic and oil paintings

    • Binder- a material in paint that allows it to stay on the surface

      • Oil paints- linseed/ dry oil

      • Acrylic paints- acrylic polymer emulsion

  • Preservation and Restoration of Art

  • http://www.scientiareview.org/pdfs/202.pdf

    • Ch. 16: The Chemistry of Art Preservation

      • Fading colors cause the picture to look completely different

  • Preserving the Past for the Sake of the Present: The Science Behind Art Conservation

  • http://www-scf.usc.edu/~uscience/art_conservation.html

    • Organic Solvents

      • Carbon-based compounds get rid of old and darkened varnish

      • Carbon-based compounds are hydrophobic

      • Solubilize hydrophobic varnish

    • Responsive Gels

      • Respond to chemical, electrical, mechanical, thermal, light-induced, or chemical stimulation

      • A mixture of enzymes, modified pure solvents, compounds with cleaning capabilities

  • Chemistry and Art

  • http://pubs.acs.org/cen/coverstory/7931/7931art.html

    • Natural resin vs. synthetic resin

    • Oxidation caused the resin to become difficult to remove and more insoluble

    • Conservation scientist is an actual job

    • Reversible painting- putting on a synthetic resin and then touching-up the painting; that way, if there is an error in the touch-up it can easily be reversed before contact with the original painting

  • How Are Chemicals Used in Art Restoration?

  • http://www.xperimania.net/ww/en/pub/xperimania/news/world_of_materials/art_restoration.htm

    • The Beginning of the Restoration Progress

      • Overall examination of the work

      • Review of the context and period when art was made

      • Studies techniques and materials at that time

      • Identify aging mechanisms

      • Must identify key elements in work; pigments,colorings,additives, varnish

      • Recognize the cause of deterioration (humidity, light, human touch, etc.)

      • Best techniques and methods of preserving the art

      • Chemistry makes this process a whole lot easier!

  • Art Conservation Glossary

  • http://www.theconservationcenter.com/conservation-services/art-conservation-glossary

    • Lead-white paint- a toxic white paint

      • 2PbCO3-Pb(OH)2

    • Methyl Cellulose- adhesive and  consolidant

      • C6H7O2(OH)x(OCH3)y

    • Mylar- a brand name for a polyester terephthalate film

  • Polyethylene Terephthalate Film

  • http://en.wikipedia.org/wiki/Polyethylene_terephthalate

    • Resin used in synthetic fibers

    • C10H8O4


About the Author

Kallie Bradley is a young chemistry student at Senior High. Although she may have struggled with wrapping her mind around chemistry in the past (and probably the future), she thoroughly enjoyed this project. Kallie is in fact interested with becoming a museum curator in the future. Right now, though, she enjoys running cross-country, reading, and food.


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