Do you struggle to create consistently bright, clear colors in watercolor painting? Are you sometimes surprised that you’ve mixed a dull, flat color from two seemingly bright paints? How can you avoid mixing ‘muddy’ color? Keep reading to find out.
WHAT IS MUD?
What exactly do we mean when we talk about mud? A muddy color is defined by Zoltan Szabo as “any combination of colors mixed too thick, or too many colors mixed or glazed together – especially two complementaries, or reflective blues with browns – resulting in a lifeless, dull and generally unpleasant color.” ( Zoltan Szabo’s Color-by-Color Guide To Watercolor, p. 13.) More specifically, a muddy color covers and obscures details of what it is painted over.
Instead of the clean, bright, transparent color we desire, we end up with heavy, dull, opaque gunk.
There are varying degrees of mud, and there are several ways to make mud. Therefore, a solution to avoid mud is complex – not one simple rule will be able to solve the problem of mixing muddy paint.

KNOW YOUR PIGMENT CHARACTERISTICS.
Knowing a paint’s attributes, however, puts you a step ahead in being able to avoid muddy color. By being familiar with whether a pigment is transparent or opaque, staining or non-staining, reflective, saturated, sedimentary, light or dark valued, for instance, you will begin to be able to predict how the paint will behave.
DEFINITIONS.
First, let’s be clear on what these terms mean!True transparent colors allow light to reflect through them from the surface of the white paper. A TRANSPARENT color maintains its luminosity or brightness, and does not build up into a thick layer. Since a transparent color lets light through, it is possible to create the illusion of a ‘glow’ of light in a painting. No matter how dark you mix these pigments, they will NOT go muddy. (Common transparent colors are Permanent Alizarin, Quinacridone Rose, Aureolin Yellow, Viridian, Phthalo Blue, Phthalo Green.) SEMITRANSPARENT paints, such as Winsor Yellow, Indigo, Da Vinci Mauve, are almost as clear as transparent paints, but will maintain luminosity through fewer layers than true transparent colors.
In contrast, an OPAQUE watercolor pigment blocks the light and prevents luminosity. While thinning an opaque color can make it somewhat more transparent, it will then lose intensity (strength). In general, you cannot see the white of the paper through an opaque paint. The more opaque a color is, the more it blocks the white of the paper, particularly if it is layered. When too much opaque is used, it can build up into a thick muddy layer. Opaque paint will also become muddy if applied with other opaques or with their complementary (opposite on the color wheel) pigments. Some opaque colors include Cerulean Blue, Indian Red, Light Red, Cadmium Yellow, Cadmium Red, Cadmium Orange, Burnt Umber, Sepia.
REFLECTIVE watercolors (like Cobalt Blue, Ultramarine Blue, Cadmium Red, Winsor Red, Permanent Rose) may go muddy when used in heavy blends or when overmixed. However, reflective paints behave more like transparent pigments when diluted, allowing them to glow.
SEDIMENTARY colors, such as Cobalt Violet,Manganese Blue, Ultramarine Blue, Cerulean Blue, the umbers and siennas) have a grainy texture (often granulating) because they are made of heavier particles that sink in water. These paints can be used to create a textured effect.
STAINING TRANSPARENT pigments, such as Indian yellow, Phthalo/Winsor Blue, Phthalo/Winsor Green, Prussian Blue/Antwerp Blue, Phthalo Violet, are bold and intense. They are NOT easily lifted from the paper. Because they are transparent, they will NOT produce mud IF mixed with other transparent colors. Mixed full strength, they create rich darks.
Still other pigments, like Lemon Yellow, Gamboge, Quinacridone Rose, Cobalt Violet, Sap Green, or Ultramarine Blue, are LOW-STAINING and transparent to semi-transparent. Intensity of these colors is average, and they can be partially lifted. If you wish to lift one color of a mixture and reveal a second color underneath (e.g. by blotting out clouds or scraping paint back to create rock texture or a tree trunk), then combine a staining pigment with a non-staining pigment.

CHOOSE PAINT BY PIGMENT NOT JUST COLOR NAME.
Warning! Be aware that color names can be deceptive. For instance, some ‘raw siennas’ are not really raw sienna at all, but are made from the yellow ochre pigments. A ‘sap green’ in one brand looks different, is made from a very different combination of ingredients, and of course, behaves differently than a ‘sap green’ from another company. You cannot count only on the color name to give you knowledge of how the paint will behave.
Instead, consider the actual PIGMENT used in the manufacture of the paint. Each pigment has been assigned its own letter and number to distinguish it from other pigments. On tubes of watercolor pigment, look for the pigment LETTERS and NUMBERS printed on each tube to tell you what the paint is actually made from – companies often include this information in small print on the tube. The letters indicate the pigment hue (color); for example, PB means ‘pigment blue,’ and PR stands for ‘pigment red.’ The numbers that follow the letters are those assigned internationally for that pigment material; for example, a true viridian paint contains PG18 (or ‘pigment green number 18), not something else that might look like viridian.
For example, Cadmium Red is made from PR108 (Pigment Red #108), while Pyrrol Red and Winsor Red are both made from PR254 (Pigment Red #254). A paint pigment has an individual personality and IS NOT interchangeable with or an EXACT match to other similar-looking paints. Since each pigment is unique, different pigments will vary in their characteristics, even though they may be mixed together to represent a ‘certain’ color. In other words, not all pigments behave the same or mix well together.
CHOOSE AS MANY SINGLE PIGMENT PAINTS AS POSSIBLE.
In order to have more control over color mixing, try also to have the majority of the paints on your palette manufactured from SINGLE PIGMENTS. Jean Dobie (in Making Color Sing, p. 10) recommends a “pure pigment palette” to avoid the frustration of “struggling with a pre-mixed commercial color that you can’t seem to make vibrant enough.” Again, pigment information is on each paint tube.

LEARN ABOUT YOUR OWN PAINTS.
Once you understand paint characteristics in general, you must become familiar with specific paints on YOUR palette. Without knowing about your own paints, you can’t know what to expect when mixing them together, or whether they’ll make mud. Which of your paints are transparent, staining, unsaturated, etc.? To figure this out, you can test your paints by creating a color chart. First, draw a line with a black permanent marker (or waterproof India ink). Allow to dry. Paint swatches of medium dark paint over the black line. Transparent colors won’t cover the black line. Opaque colors will. Staining colors will look quite dark. (See Below.)
Or check the color charts provided by paint manufacturers (e.g., Daniel Smith or Winsor Newton) that include a color swatch and describe characteristics of each of their paints. These will tell you how transparent, staining, granulating, etc. a paint is, and often the actual pigments used. If you’d like more in depth information about paints/pigments, go to handprint.com, https://www.handprint.com/HP/WCL/waterfs.html. Another resource, although somewhat dated, is The Wilcox Guide To The Best Watercolor Paints, (2000), available at amazon.com.


SECRETS WE’VE LEARNED.
Now that you have this knowledge and information about your paints, we can get specific about how to avoid muddy colors!
1.) If you mix a transparent color with another transparent color, you will NOT make mud.
2.) Mixing a transparent color with an opaque color (when not mixed too thickly) will usually not create mud. However, when too much of the opaque is used, it can build up into a thick, muddy layer.
3.) If you combine two or more opaque colors, mud will result.
4.) Complementary colors mixed too thickly to create a very dark color can result in mud, especially if one of the colors is opaque, or if a reflective color is a part of the mix.
5.) The earth colors (umbers, siennas, ochres) usually don’t mix cleanly with other colors, since they contain black, and mixes containing them tend to result in grayed mixtures.
6.) Similarly, triads (blends of three paints, a triangle of colors on the color wheel) combine all three primary colors and can result in mud when mixed thickly from colors that are not transparent. Using EQUAL amounts of the three primaries in a mix will create a dead neutral color. Instead, have one of the three colors predominate to blend a more lively, interesting mixture.
7.) Muted color (although not necessarily muddy) results from not paying attention to color bias in your mixing. If you are unfamiliar with color bias, refer to ‘The Color Wheel, Color Bias, and Color Mixing in Watercolor (7/2/2019), https://leemuirhaman.com/2019/07/02/the-color-wheel-color-bias-and-color-mixing-in-watercolor/.
8.) The trick to avoiding mud in middle values is to remember that middle values can lean light or dark. To mix a middle value that leans light and is NOT muddy, combine an opaque and any number of transparent colors. To produce a dark middle value that is NOT muddy, mix an opaque pigment with a staining transparent. (Powerful Watercolor Landscapes by Catherine Gill, p.121.)
9.) You will also tend to make mud if you have chosen to use a pre-mixed tube of gray or black instead of mixing the color from single pigment paints.
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I love all the knowledge you give freely. It is so informative and easy to grasp. Thank you for sharing your gift with us!!
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What a wonderful comment! Very supportive. Glad I could help.
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