An introduction to paint and pigment properties
In our last post we talked about color mixing and being able to get a whole range of vibrant colors from a small selection of paints. I also mentioned a whole bunch of specific paints with pigment numbers at the end, and I bet a lot of you get confused by this sort of information. I know I did when I first started exploring beyond my very first pre-made student grade 12 color palette.
You might have noticed that your paint tubes or pans come with some weird symbols and numbers and stats that might not make any immediate sense. Artisanal watercolor makers might also share some info in their shop about the colors they sell. But I’m here to tell you that this sort of information is your best friend when researching which colors to get! And I’ll give you just enough background on this to prevent you from getting overwhelmed by it.
What exactly are watercolors?
Watercolors are made up of some form of color substance that is mixed thoroughly with a binder – something that keeps the paint together and prevents it from just falling off the paper when it dries. This applies to all sorts of paint. Oil paints are color plus oil, acrylic paints are color plus acrylic binders, and watercolors are usually color plus Gum Arabic. The paints may also contain preservatives or additives that helps with re-wetting the color, or makes it behave differently in water. But the most important ingredient is the colorant. This is what makes the paint look and behave the way it does- the binder is simply a vehicle for the colorant.
The most frequently used colorants for watercolors are pigments. These are chemical particles with a certain color, that will keep their shape and properties even when thoroughly mixed with the binder. This gives the paint unique qualities such as granulation, staining abilities, and mixing properties. Two pigments might look the same in their powder form, or in a pan of paint – perhaps exactly the same shade of red – but they might perform completely differently when mixed with water and applied to paper.
To avoid confusion: In the rest of this article, pigment will refer to the color particles themselves, which are specific chemical substances, whereas paint will refer to the finished mixture of pigment and binder.
I’ll also mention that there’s another type of colorant that I see mainly in watercolor inks and handmade paints, which is dyes. The main difference is that the dye will react directly with the binder and water and dissolve nearly completely, unlike pigments that are simply suspended in the binder. Another important difference is that dyes are nearly always fugitive, meaning they will fade with time and exposure to light. Pigments, on the other hand, can be lightfast, or permanent.
Pigments are named based on traits like chemical properties or origin – like Cobalt Blue or Indian Yellow. They also have a number that makes it easier to separate one from the other. Pigment numbers might look like this: PY154. The P stands for “pigment”, the Y stands for “yellow”, and the number is simply the number assigned to this pigment. Blue pigments are marked with B, brown with Br, red with R, etc.
Pigments vs Colors
To sum up this section very briefly: pigments are universal, while colors (and paints) are individuals.
And by that, I mean that specific pigments are the same chemical substance and very often have the same properties no matter which paint it is mulled into. You should be aware, however, that some pigments, like Red Iron Oxide PR101 can appear with different shades and properties based on how the chemicals are treated.
Pigments might be marketed under different color names, and these are often fancy or cute names like “Sunshine” or “Ruby”. Paint makers – both big and small brands – should always include information on the pigments that went into the color they’re selling. If this information is not available on either the packaging, in the catalogue or on their website, you should not feel like a nuisance when contacting the maker directly to ask for pigment information.
Another important thing to notice is that some paints contain more than one pigment. These are often called “convenience colors”. You should be able to mix these yourself if you have the single pigment paints on hand, but it might be convenient to have a premixed color at hand if you find yourself using that particular mix a lot. Sap Green is probably the most widely known and produced convenience color, since no single pigment with the color sap green exists. Other multi pigment paints aim to achieve special effects, like pigment separation, by mixing pigments that don’t blend smoothly with each other. If this is not the desired outcome, knowledge and expertise is required to create multi pigment paints that behave consistently. Lastly, some paints contain multiple pigments to create a hue – a substitute for a pigment that is toxic or no longer available. It might even be a case of cheaper pigments mixed together to mimic the color of a more expensive, more sought-after pigment.
This topic will be discussed more thoroughly in a future post, since it is a very interesting one.
Pigments come in all sorts of colors, and artists might feel like they’re walking into a bright and colorful candy store whenever visiting their local art supplies shop. But in addition to looking for your favorite colors in the store shelves, you should also know that pigments have important qualities and properties that affect how they handle, and how well they keep up appearances over time. The information on each of the following properties should be available for all paints by all makers, the same way pigments should always be listed. Again: don’t ever be afraid to ask watercolor makers about the qualities of the paint you consider spending money on.
This is the most important property of your paints and it is determined by the behavior of each pigment that went into the paint. It tells you whether your paintings will fade. And if you plan on hanging your originals on your walls – or even sell them – you want to know that the colors will not lose their vibrancy when exposed to light. If you mainly use your originals to create digital copies or prints, you might not care about lightfastness.
All watercolor makers should have a system for marking their products with permanency, and you should always check the rating of a certain paint before buying it. If you know which pigment the paint contains, you can always look up the lightfastness of this pigment in official databases. Remember – pigments are chemical substances with fairly consistent properties no matter where they come from.
Pigments will, to different degrees, stain the paper – and your brush, and the adjacent pages in your watercolor journal, and your palette. Other pigments, on the other hand, are non-staining can be
lifted from the paper by using a clean wet brush or towel, and you are left with clean, white paper again. This is useful for a lot of purposes, including creating highlights or fixing mistakes.
Watercolors are often wanted for their delicate, luminous transparency, but there are many pigments in use that are actually opaque. Most of them are transparent when diluted with water. Transparent watercolors can be built up to their full strength by adding several layers of paint, while opaque watercolors might hide the layers beneath it. The entire color spectrum of pigments contains both transparent and opaque colors, and you should know the difference before choosing which pigments to get.
A most interesting property of pigments that happens when heavy particles sink through the water and settle in the physical texture of the paper. This can create exciting effects and delicate patterns. But if you want smooth, even washes you should look for pigments that are non-granulating. Keep in mind that the same pigment can be more or less granulating depending on how it is processed by the maker, and you should ask the maker about their specific paints if the amount of granulation is important to you.
I’ve added this section to briefly inform you that some pigments are toxic to animals and plants. Because of the tiny amount of pigment in your half pan or paint tube, this does not mean that your paints are dangerous to either use or store in your home. It shouldn’t be a problem to rinse your water jars in your kitchen sink, either. But for the people who make the paints – and therefore work with large amounts of pigment at a time – it is important to be aware of the risks of inhaling, ingesting or unsafely disposing of toxic pigments. Some artists also prefer not to contribute to the continued use and distribution of toxic art supplies and choose to avoid buying this type of pigment. Daniel Smith, one of the largest watercolor brands, have stopped making paints with cadmium pigments, instead offering similar hues with non-toxic substitute pigments.
To sum it up
Get to know your paints and their behavior!
Make up your own mind and find your personal favorites
Always look for pigment information about the paints you want to buy
Don’t be afraid to reach out to watercolor makers to ask for more information (Keep in mind: this is not the same as asking for their paint recipe)
Make conscious choices about which paints to get, based on your painting style and what purpose you want the paints to serve.
Helpful tools to choose watercolors for you palette: http://handprint.com/HP/WCL/wpaint.html
An overview of all the common pigments currently in use: http://handprint.com/HP/WCL/palette1.html
A color wheel that places the different pigments based on hue and saturation: https://www.handprint.com/HP/WCL/CIELAB.pdf
- Color of Art Pigment Database
Updated, extensive database of pigments and their properties http://www.artiscreation.com/Color_index_names.html#.XiWY9MhKhPa