The Unique Characteristics of Watercolor Paint

Watercolors in pans
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Watercolor is a medium known for its transparency and fluidity. There are three kinds of watercolor paint - tube, pan, and liquid. The following are some of the characteristics common to all watercolors.


Like all paints, watercolors come in student grade and professional grade quality. The professional grade has a higher concentration of pigment and better permanence ratings. Student grade paints use more fillers and may use cheaper pigments, making them more affordable, but not as satisfactory in terms of color, intensity, and permanence. 

Lightfastness and Permanence

Lightfastness, or permanence, refers to whether the pigment can withstand exposure to light and humidity without fading or altering in color. This is graded as excellent (I) to fugitive (V), under the rating system of the American Society of Testing and Materials (ASTM) and is denoted on the paint tube label. Fugitive, a rating of V, indicates that the color will bleach very quickly. Here are directions to perform your own lightfastness test. It is wise to use only those pigments with a rating of I or II in order to avoid any fading or discoloration.


Watercolor paint is identified as transparent, semi-transparent, semi-opaque, or opaque. The semi-transparent and semi-opaque watercolors may also be called translucent. Transparent watercolor means that light is able to shine through the paint onto the white surface and reflect back to the eye, creating colors that seem to glow. It is the white of the paper glowing through the transparent paint that gives watercolor its luminosity. Opaque color blocks the light, preventing it from being reflected off the paper, resulting in colors that are somewhat duller in appearance.

You can test the transparency and opacity of your paints by drawing a black line, using a sharpie or black acrylic paint, across which you paint the colors you want to test. Transparency/opacity is determined by how much black the paint hides. If it hides none, then it is transparent, if it hides much of the line, then it is considered opaque. Keep in mind, though, that the beauty of watercolor is that it is generally a transparent medium, so it is difficult to achieve complete opacity with watercolor paints alone.

You may also test the transparency of your colors by creating a grid of overlaying colors.


Water is the solvent that is mixed with watercolor paint to make it the right fluidity and concentration, whatever the type of watercolor paint being used. How much water you mix with the paint will determine how intense the color is as well as affect its transparency. Different hues can be created by mixing colors on the palette. Once the paint has dried, the water evaporates, leaving a color that is a little lighter than when wet. 


Watercolor is reactivated when wet, unlike acrylic paint that has a plastic polymer binder, so can be reworked at any time after drying as long as it hasn't been sealed with a varnish. This will render it waterproof and protect it from environmental factors such as light, humidity, and dust, but will also make it unworkable. Until then, you can add color to a color that has dried in order to strengthen it or create another hue by mixing it with another color.

Watercolor is a great medium for many subjects and purposes. Experiment with some watercolors on your own to learn some of their properties and characteristics.