There are many technical terms used to describe the properties of paint. A little chemistry know-how can help you become a better painter—but don’t worry—we’re not talking about balancing chemical equations or memorizing the periodic table here! This ongoing series of mini-articles will help you get to know your medium on a deeper level. Paint Talk: Part I is about Lightfastness.
How to Interpret Artists’ Quality Paint Labels
Have you ever wondered what all the symbols and numbers on your paint tubes mean? Reading your paint labels can be like reading a nutrition label on a food package—there’s a lot of information there, but what to make of it? Many of the numbers on your paint tubes represent standardized information about the paint's chemical properties. For example, if you're trying to match a particular color across brands, and each company uses a different proprietary color name, you can match the same color index number between brands. If you're looking at Studio or Craft paint, you might not be so lucky—only the highest quality paints list all of the paints' attributes. Information can vary from brand to brand, but most labels displayed on artists’ quality paint reveal the following information:
- Paint swatch of the actual paint
- Color name
- Pigment(s) and index color numbers
- Lightfastness or permanence rating
- Manufacturer’s Color Number
- Series Number
A Paint Swatch to Show Opacity
Most tubes have a swatch of the actual paint near the cap so you can see the opacity and vibrancy of the color. In art stores, professional paints are usually displayed with a larger swatch on the shelf to give artists a better idea of what the paint will look like once it’s dried.
Artists’ quality paint should have a swatch painted over black stripes to demonstrate opacity. Synthetic pigments, like Quinacridone Red, tend to be thinner and more transparent than natural pigments. Natural earthen colors like ochres and umbers are more opaque and have great coverage because they are so dark and flat. Synthetics are great for glazing.
Some paint tubes also label the transparency/opacity of each color with a letter. For example, Sennelier uses the following letter labels on the outside of their paints to describe opacity: T for transparent colors, S/T for semi-opaque colors, and O for opaque colors.
e.g., Cadmium Red, Phthalo Green, Ultramarine Blue, etc. Every tube of paint, not matter the quality, should list the color name! Color names can vary from brand to brand--some are very staightforward-sounding and reveal the raw materials used to make the color; others are quite creative and some sound very scientific. We will eventually publish a special blog post about color names and their histories, so stay tuned!
Pigment(s) and Index Color Numbers
The types of pigments used in the formula may be listed on the tube. Index color number is not a concern to most painters, but it’s fun to know about the origin:
In the 1920’s, the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists decided that there needed to be a standard classification system for pigments. Paint companies and other pigment manufacturers use a variety of proprietary and generic names for their colors. This scientific classification system was invented so that we would have a reliable international standard to identify colors by chemical structure. This system makes it easier to study historic colors and to manufacture new colors in the future.
Lightfastness or Permanence Rating
AA and A, or I and II indicated colors with high permanence. Artist quality paint won’t degrade as much over time from light exposure. The American Society for Testing and Materials determines lightfastness and sometimes a specific ASTM color number is included here as well.
Manufacturer’s Name and Additional Numbers
Companies like Golden, Winsor and Newton, and Liquitex will also use their own numbers to identify the color or pigment, in addition to the Color Index Number.
Artists’ Quality paints are grouped into different price bands based on the cost of the raw materials used to produce them. The more expensive the raw materials, the more expensive the paint. Manufacturers often split artists’ paints into series, like Series A and Series B.
Paint series can also be grouped by number. Higher letters or numbers often indicate a more expensive paint. Cadmiums are generally the most expensive, in the 7-9 range. Paint made with less expensive raw materials like umbers will be labeled Series 1 or 2.