A hue is the actual color of something, such as naphthol red, sap green, or ultramarine, or any name we give a pigment or combination of pigments. Essentially, a hue is what we more often refer to as color, though hue is more technically correct.
And yet, the word hue in the art world is far more complicated than that simple definition. It's important for painters to understand all of its meanings and uses so you know what you're buying for paint. It doesn't matter if it's an oil, acrylic, watercolor, or any other type of paint, this applies to all of them.
The first definition of hue is that it refers to a color family. For instance, all those yellow tubes of paint in your art box are yellow hues and all the blues are blue hues.
In this sense, the word hue refers to color, but it does not distinguish if it's cadmium yellow, yellow ochre, or Naples yellow. They are all yellow hues because they appear in the yellow family of color on the color wheel.
Paint manufacturing is where the word hue really gets confusing. First of all, you must remember that paint is made by combining pigment with a binder. The amount of pigment in a paint can vary from one manufacturer to another and within different quality grades. The word hue is often used to distinguish these.
You might, for instance, see hue on a tube of student-grade or more economical paint. Pigment is not cheap, so to cut costs, the paint makers will use less pigment in paints that they want to sell for less. Quite often, they make up for this with fillers to bulk up the paint without affecting the color and dyes to match the desired color.
The resulting paints tend not to be as lightfast or have the archival durability as professional-grade paints. In this instance, the word hue on a paint label is not the most desirable thing and many artists call these "cheap imitations." This is why your art instructor may recommend that you upgrade to professional paints as soon as you can afford to.
There are, however, many instances where hue on a paint label is not bad at all. Those lower-grade paints led to a lot of confusion for artists and many misconceptions that all hue paints should be avoided by serious and professional artists. The reality is that sometimes hue is absolutely necessary so we can enjoy our favorite colors.
Paint has been around for centuries and many of the most common colors we use today are known as "historical colors." These include Prussian blue, cadmium red, hooker's green, and most of the paints we consider "standards." The problem is that the original pigments used to create these colors are not always available.
The reasons for the availability issues of some pigments vary. Some pigments, such as Prussian blue and hooker's green, are known as "fugitives," meaning they are not naturally lightfast. Others, like cadmium red and cobalt blue, are toxic. Still, other pigments may be too expensive to source, such as quinacridone gold and manganese blue. In some cases, such as Indian yellow, the process of sourcing the pigment is viewed as unethical or inappropriate (it was made from bull urine).
All of this means that the true source of the pigments originally used to create paints of these historical colors is gone for one reason or another. To keep artists happy and continue to offer those tried and true colors, paint manufacturers now have to mix pigments to replicate the original color. These recreated paints are labeled as a hue on the tube.
It is very likely that other pigments will someday be replaced with hues as well. To make it even more confusing, some colors are only available as hues. Gamboge hue is a perfect example of this because it is not found as a natural pigment.
As long as you are buying professional-grade paints, hue is a good thing. Without that word, all of these paints would not exist. The good news is that reputable manufacturers have taken careful steps to accurately reproduce the paint colors without the known issues associated with the pigment. This means you'll get high-quality paints that are safe to use, lightfast, and produced in an ethical manner.
It's a win-win for artists, really. The problem is getting past the stigma of those low-grade hues. Yet, if you shop smart, it shouldn't be an issue. It's just one more reason why you really need to understand pigments, colors, and how paints are made. After all, paints are the most important tool for painters.