Each paint tube label varies depending on what company manufactured the product. Each label should contain the name of the company that manufactured the paint, the color that is inside the tube, the binder or vehicle that the colored pigment is suspended in, the amount of paint in the tube and the country in which the paint was made. There should be an indication of whether or not the paint is student-grade or artist-grade material.
Artist's grade paint, which is typically higher quality, will be more expensive because it contains a higher concentration of pigment and higher quality oils are used.
The transparency or opacity of the paint may also be listed on the label. This can be important information for artists who want transparent glazes or layers of paint that allow the more opaque colors to show through. The more opaque paints do not allow light from other pigments to show through, creating a more solid paint with higher coverage.
The ASTM rating system (The American Society for Testing Materials) is the most widely acknowledged and trusted system for oil paints. Tubes of paint will list different types of rating systems, including numbers, stars or letters. The ASTM system rates paint using a class system from I-V, with Class I recognized as the best quality paint with the longest lifespan and a high rating of lightfastness, meaning the paint will not fade for hundreds of years. Class V paints may fade after only two years. Artist grade materials are considered as Classes I, II and III.
Another well respected rating system in the art world is called Blue Woolscale. Similar to ASTM, it can be found on labels and rated between 1 and 8. The higher numbers are more lightfast and permanent. Blue Woolscale 7 and 8 are excellent with the ability to last longer than 100 years without fading.
Oil paint contains pigments and oil. The pigments, both natural and synthetic, can vary dramatically in their lifespan on a canvas. Pigments that rate low on the paint series number scale are considered "fugitive" colors, meaning, they will not hold their color for several years. If a color such as yellow ochre, which usually receives a high series number, is mixed with sap green, which is a fugitive color, a responsible rating system will rank the final mixture based on the least lightfast material.
Oil in paint is usually linseed oil, although safflower, poppyseed and walnut oil can also be found. Paint manufacturers are always looking to advance products within the industry and new oil mixtures can be found coming out in product lines regularly.
Student often use inexpensive paint to experiment and create exercises with. They are similar to professional oils, but contain lower pigment concentrations. They usually have a more limited range of colors and the more expensive pigments are recreated into hues, which may not have the same characteristics of full-strength colors.
Professional artists paint contains a high-quality full pigment load which is suspended in a binder. Usually the binder is linseed oil mixed with a drying agent such as safflower oil. Artist's paints can usually be used directly out of the tube without mixing in any thinner or medium for flow. The best quality paints resemble butter. With a wide range of colors available, it is not necessary to mix colors, as they are already available pre-mixed. Too many colors are mixed together can dull paint.