As a plein air painter, an interesting topic that has played an important part in my life is color, specifically the color of paint. For most of my adult life, I worked in the paint industry as a color matcher, and as a chemist. A color matcher designs colors for various industries, and in my case, it involved developing touch up paint. I think we all know what touch up paint is as you can purchase small bottles of it at hardware stores, appliance centers, and even at automotive parts stores, but its also available at the industrial level for a large number of industries.
As a color matcher I had a process for matching colors that were to be used in industrial, or commercial products. This process involved the companies sending manufactured parts to us, and I, or we, developing formulas either a computer, or in my case, by using my eyes and training. Generally, we preferred that the matching of colors be done as inexpensively as possible, but it had to be accurate. Sometimes your only choice was to use expensive colors, but whenever possible, especially when it involved grays, brown, beiges and the like, inexpensive choices could be made. And believe me, there were a lot of grays, beiges and browns. In those cases, our first choices were usually white, black and some combination of red and yellow oxides.
Because of this, I’ve always understood the blending of colors to be simple unless, for some specially reason, a greater degree of difficulty arose. For example, we really tried to avoid metamerism. Metameric colors develop when the pigments used too make the paint change color in different lights. This is not something that an artist normally worries about, although the issue did arise for me at one time when I was creating a mural. I ran short of yellow in the middle of painting the mural, and bought a second tube. But when I finished the two panels of the mural, and took them outside, the yellow on one panel was significantly redder than on the other. Obviously, I had bought the wrong color of yellow, but that meant that I had to repaint the yellow portions of the mural I had already finished using this second tube. Light can play tricks on a painting, but as long as artists pay attention to what products and pigments they are using, this shouldn’t be an issue.
Another way I see the blending of colors is that almost all grays are basically white and black, and that the grays they create, lean towards a bit of a blue shade. I mention this because many artists tend to use complimentary colors to develop grays, or the dark colors used in painting shadows, while I prefer to simply develop the color I see in the simplest way, rather than impose art school color theory upon the blended colors in the painting.
A good example of this is the use of violet and ultramarine blue in creating dark shadows. Much of this is color theory and a way of creating colors that has arose with Impressionism in the late 19th century. It is taught in many art schools, but not everyone agrees. Some artists prefer to keep it simple as I do, and to be truthful, unless an artist’s intent is to create unrealistic colors in a painting, such as was done with some of the Post-Impressionists, its probably not necessary. But it really is more of a personal choice than it is some kind of rule of artistic law.
I do use ultramarine blue, although it was never used where I work. Chemically, it is not a lightfast color, in the way that phthalocyanine blues are. Instead, I came about it in an attempt to find the right blue to use in painting sky. I think a lot of artists find it that way. I too found that it also worked for shadows, but I rarely blend it with violet. My brother, who is school trained as an artist, prefers using Prussian blue instead. I think the reason I never used that color is that when I was shopping for the right blue, I found that the vast majority of blended blues available in oil paints were simply endless combinations of white and phthalocyanine blue. “Phthalo” blue was what is used what is primarily used as a blue in industrial coatings. It’s a durable, man made pigment, and its relatively cheap. Some lines of oil paint had close to twenty different blends of white and phthalo blue. This is something you have to watch for. These days, the number tinted oil paint I find being passed off as colors are much less than there use to be. That’s good if we want artists to know how to blend their colors.
One last thing I should mention is that pigment choices are pretty strong on the cool side of the palette, but its much more difficult to find what you want on the warm side. Because of this, most artists prefer to use cadmium colors. They are bold, and they are very bright. They are also very expensive, and for those who are concerned over health issues, they are more dangerous than other colors, so you need to be careful when you paint.
There are around 200 known pigments, which is a lot less than you might think. The Phthalos make good greens, blues, and even a blue violet. Quinacridones make a good cool red as well as good violets. But the only really good red is DPP red, a recently developed color that costs a heck of a lot of money. If you’re old enough, you’ll remember that red from all those Dodge and Chrysler ads back in the 1990s.
As for oranges and yellows, one standby is the diarylide colors, which are really sensitive to fading, but they do have one benefit. The cadmium colors tend to look a little dirty once you add white them, while the diarylides do not. They maintain a cleanliness of color when added to white. So does Hansa Yellow.
My intent in this is simply to explain that there is more than one choice in deciding which colors an artist may use in painting a picture. At the same time, while there are choices, they may not seem as limitless as we would like them to be. There are colors that were once used that have been abandoned for one reason or another, such as the instability of the color in light, or because of chemical dangers. So, in other words, we do the best we can with the pigments we have and the choices we make.