Color Curriculum

Granulation, Flocculation and Two-toned Colors

By Carolyn Payzant

Originally appeared in The Botanical Artist – Volume 14, Issue 4


As they are all intertwined, you need to understand the principles of particle size of pigments, granulation, flocculation, and two-toned colors.  

Particle size – Pure raw pigment is not transparent. Remember pigment starts out as a powder. So no matter how finely the manufacturer grinds their pigment there are still particles in each and every tube of paint. These particles never dissolve. They are always on your paper and no light passes through them. The color that you see on your paper is a reflection of these bits and pieces of stone, bone, crystal or metal.  The smaller the particle size the more paper you can see, making the color appear more transparent. And in reverse, the larger the particle size the more paper is hidden making the color appear less transparent. I love this analogy: small pigment particles are like dust on a table (likening it to transparent pigment) and larger pigment particles are like saw dust on a table (likening it to semi-opaque to opaque pigments). This leads to several challenges: 

Challenge: the larger the particle, the more opaque the pigment but on the other hand an opaque pigment is not necessarily granulating.  

Challenge: Using white pigment as the highlight of any area on your painting will lose the appearance of sheen and appear chalky. All white pigments are either semi-opaque or opaque.  

Challenge: Never mix an opaque or semi-opaque pigment with another opaque or a semi-opaque pigment or your mix will quickly go muddy. An opaque pigment should only be mixed with a transparent or semi-transparent pigment. Mixes of opaque and transparent pigments will always have the attribute of the opaque pigment, giving them a chalky appearance.  

In The Botanical Artist, Volume 14, issue 3 – September 2008, I listed all of the semi-opaque, opaque and granulating pigments.  

Granulating – When the manufacturer doesn’t grind or is unable to grind the pigment finely enough the large particles sit on your paper and you see them as speckles. Almost all black and natural earth pigments leave speckles on your paper. The size of the speckle depends on the particle size. Pick up any rock and really analyze it. We tend to forget that natural earth is made of several components – some heavier or softer than others.  

Challenge: If you really want that specific granulating pigment but do not want the granulation: place pigment in a test tube, add water, shake, let the large particles sink to the bottom of the tube then pour out the colored liquid onto your pallet and let the liquid dry. There will be very little granulation left when the liquid dries on your pallet.  

Flocculating and Two-toned Pigments: These terms refer to the attributes of some pigments prone to separating before your wash dries. This fabulous spontaneous reaction happens by one of two processes: a. Two-toned results when one particle in the pigment is heavier then the other.  The heavier pigment settles into the texture of your paper while the lighter particle floats on the surface. b. Flocculation occurs when particles in the pigment react to one another and  separate, forming clumps where some particles cling together or where particles are forced apart. I am not an expert enough to know which process is active in any specific pigment. I just know the powers of these attributes are stunning.  

Challenge: When mixing granulating or flocculating pigments with non-granulating or non-flocculating pigments, both attributes are passed on in the mix. This new mix can give you a whisper of texture or an “in your face” flamboyant texture, great if you are painting rocks or for our purposes tree bark, dry leaves or nuts and fruit.  

Challenge: I have not tried this yet but I read that you can add liquid alum to your pigment and create your own flocculation. If any of you try this and it works: please let me know. For the botanical artist, finding and learning how to use these pigments is worth the effort. They don’t like being fiddled with – so with one stroke of the brush, lay down the color, and let the magic begin.  

I am sure that there are many more two toned or flocculating pigments, but here are a few that I know.

PY150 Nickel Azo Yellow DS
PY151+PO62 Gamboge MG
PY153 New Gamboge DS
Indian Yellow DR
PO49 Quinacridone Golden Lake MB
Quinacridone Gold DS
Quinacridone Gold Deep DS
Quinacridone Sienna DS
PB29 + PO49Undersea Green DS
PB36 Cerulean Blue MG
PG7+PB15 Cascade Green DS
PG7+PY3 Permanent Green Light DS
PG36+PO49 Sap Green MB

PV19 + PY97 Rose Dore WN
PV14 Cobalt Magenta DR
PV16 Manganese Violet DS
PV19+PY97 Ultramarine Violet MG
PB27 Prussian Blue WN
PB29 Ultramarine Deep H
PB35 Cerulean Blue WN
PB73 Cobalt Blue Deep WN
PG7+PO49 Sap Green DS
PBr11 Lunar Earth DR

Chart Key: DS = Daniel Smith, MG = M. Graham, DR = Daler Rowney, WN = Winsor Newton, MB = MaimeriBlu