A lot depends on the medium you are using.......creating muddy mixtures with wet paints is a fairly easy thing to do and a great deal will depend on the quantity and type of colours being mixed. Creating a muddy effect in pastels, therefore, ought to be less of a problem, since they are a dry medium and no mixing on a palette is required...yet the subject STILL comes up.
So ..let's glance briefly at wet mixing.
When you mix, say, ultramarine blue (reddish blue) and alizarin crimson (blue-red) nearly all of the yellow rays present in the light that strikes the pigments are absorbed and a bright purple or violet will be the result. BUT when you mix ultramarine blue (reddish blue) with a cadmium red (orangey-red), which contains a good deal of yellow, the yellow in the cad red will change the mixture in a very different way, and it might become muddy-looking to your eye. So, the moral of the story is to understand colour rules. There are vast numbers of books available to you, so there is no excuse NOT to know colour rules! Applying them is another thing. Trial and error can work...but UNDERSTANDING works better.
A few things to think about:
- If you mix complementary colours together, (do you know what these are???) you will usually end up with a greyish or brownish mix....which can be lovely, but not if you do not want this! ( What looks muddy in one painting, may be quite different used in a different context.)
- Do you understand "Triads" ?- again, worth looking up. Having said that.....
- Too many colours in a mix, and too many layers of paint, will almost certainly result in a muddy finish.
- If you want a sparkling, transparent watercolour painting, then opaque and earth colours in watercolour can quickly "interfere" with a mixture because they have very little transparency. So, if you used, say, yellow ochre instead of raw sienna, you may feel that the mix you created is absolutely not what you had intended, despite the fact that yellow ochre and raw sienna seem to be quite similar!
- which of your pigments are transparent, non staining?
- Which are stains?
- Which are opaque sedimentary pigments?
Another few handy thoughts..................... Did you know that Winsor Blue is forty-five times stronger than French Ultramarine?
Are you aware that it is a COOL colour blue, leaning towards yellow?
Did you know that Winsor Yellow is opaque, while Aureolin is transparent?
Did you know that Burnt Sienna is fairly transparent despite sounding as tho it ought to be an earth colour?
Do you rely on the old adage "There are three primary colours - red, yellow and blue" ? If you do, this could be part of the problem. You need to know WHAT RED, WHAT YELLOW and WHAT BLUE you are using and why. This little colour wheel is far more useful than a simpler one showing one red, one blue and one yellow.
I would refer you, at this point, to Michael Wilcox and his color mixing theories. His book, still available on Amazon, is called "BLUE AND YELLOW DON'T MAKE GREEN". There is plenty to learn there and you might find it rather eye-opening. I certainly did.
Another useful resource is Nita Leland's page, her split-primary system, which is essentially the same principle: but she gives you actual paint names:
Before I go on to Pastels, look at this gorgeous image from Royal Academician Ken Howard. Painted with plenty of so-called "mud", yet it so beautifully describes our UK grey weather and those touches of red and orange absolutely sing, making the neutral greys and khakis all the more effective and absolutely right - those "muddy" colours seem inspirational!:
So - what about dry materials like pastels?
One simple answer to a muddy finish is to look at how you are working.
Are you working flat, allowing sleeves to brush across the picture and unwittingly mix the colours? Working flat on a table with pastels is really not advisable. The dust you create needs to fall away or it will contaminate the layers of colour.
Are you layering unthinkingly, just covering up one colour area with another, perhaps to disguise, perhaps to cover the paper...whatever, "unthinking" is the important word. If you layer complements without fixing, for example, you could well be picking up underlayers which will physically mix with upper layers. Visual mixing - tiny areas of red, for example, peeking through a larger area of green, can work to make an exciting colour mix...but mixing the red and green together physically can result in browns.
Look at this simple example. On the left, red marks were made first, fixed, and then green added over the top. The green remains unsullied because the red has been fixed. On the right, red was put down first, and green all over the top, without fixing.
BUT A good rule of thumb for the pastellist.......mud is not really mud. It is usually a neutral hue of some kind. Unrelieved areas of neutral greyish colour, in the middle to middle-dark range, could arguably be described as mud, but in fact, it is another word beginning with M which describes areas like this....Monotony. What is needed to avoid monotony, is areas of contrasting value, and intensity. Then, "mud", or Monotonous colour passages, can in fact accentuate, or contrast with, more intense areas of colour in a painting. It is all about balance, and design. My painting below, Roses on a glass table, contains a large number of "greyed" colours, but there are also small touches of intense, sharper, more intensely colourful notes, which help to prevent monotony.
By and large, if your tones are right, you will often find that in a pastel painting, there is far less chance of "mud" than with any other medium. But again...your painting will come along in leaps and bounds if you really know the colour wheel, colour temperature, how to distinguish darks from neutrals and how to balance your colours and use neutrals to good effect.
I wish you happy, mudless painting!