Sinkers and Floaters

Watercolor is unique as a wet medium since the vehicle (Gum Arabic) and the water evaporate and disappear when the paint dries. The only thing left on the paper is the pigment. This characteristic can make some of the other characteristics of the pigment be just as important, if not moreso, than the color itself: things like transparency, granulation, tinting strength, diffusion, value range, etc. Understanding these characteristics can often be daunting.

After years of pigment studies, I have chosen to categorize pigments simply based on whether they sink or float in water. Throughout my blogs I will often refer to a pigment as a ‘sinker’ or a ‘floater’. So let me explain what I mean by this, and how you can easily determine which category a particular paint falls under.

First and foremost, it is important to understand that all pigments are particles. They never dissolve in water. I like to think of them as tiny grains of colored gems. Pigment particles vary in size and density depending on the pigment, which determines how they act in water.

To determine if you’re working with a Sinker or a Floater, mix some of it in a small glass container – I prefer a shot glass.  You want to be able to see how the pigment settles. Let your mix sit for 20-30 minutes, then look at it and see how much it has settled. The larger and/or denser pigment particles will settle quickly, while the very fine/low density particles will stay in suspension.

The way a pigment settles tells you a lot about how it will act when applied to paper. This same settling phenomenon that happened in the shot glass will happen on the paper. The heavier pigment will go quickly to the paper, while the finer particles will stay afloat and be affected by the flow of the water in which they are suspended. Using these simple categories, you will soon have a better understanding of your paints.

 

Three Categories

  • Sinkers: Fully/Mostly settled in 20 minutes. Cobalt blue is an example of a sinker.
  • Floaters: all or almost all of the pigment stays in suspension. Phthalo blue is a floater.
  • Hybrids: No matter how long you let the mix sit, some of the particles settle out, but some stay suspended. There are not a lot of hybrid pigments. The Cadmiums are examples of hybrids.

Some Characteristics of Sinkers

  • More likely to be non-staining. This is the characteristic of most pigments made from non-organic sources – like metals and stone – cobalts, magnesiums, iron ores, to name a few.
  • Sinkers can coat the paper, acting like sizing. This can result in slower drying time for a wash, and increased lift-ability.
  • Some sinkers are granulators, whereas floaters or hybrids are never
  • Sinkers are more opaque than floaters. Try to apply settlers in the first layers of paint laid down and avoid using them in glazes unless they are extremely diluted.
  • For the most part, sinkers are weaker tinting than floaters, but tend to be WYSIWYG (What you see is what you get) – there is less change in their color and chroma as they dry.
  • Some sinkers stain, but the really fast sinkers are usually easy to lift, which means that they can also be disturbed with subsequent layers (especially if there is a lot of water and brush action). Also more likely to lift when frisket (masking fluid) is used over them.
  • Sinkers can be used full strength without bronzing. The bronzing comes from an excess of gum Arabic, which is the binder in watercolor. Sinkers have a higher ratio of pigment to gum Arabic than floaters.
  • Some examples of sinkers include: Cobalts, Ceruleans, Viridian, most non-organic earths or any pigment made from earth-sourced materials, like rocks and gems. [Note that almost all modern pigments are made in the lab even though they may have the same chemical composition as those taken from the earth. Ultramarine Blue is a good example of this.  Lapis Lazuli, a rock from the mountains in Afghanistan, was the original source for this gorgeous pigment.  At that point it was more expensive than gold itself.  Today it is made by the chemist, and is one of the least expensive pigments available.]

Some Characteristics of Floaters

  • Most floaters are fairly strong, which means they will be semi-transparent to transparent. It is important to figure out which ones are transparent in the way that you use them. Remember – any pigment is transparent when diluted enough and any pigment is opaque if applied thick enough.
  • Floaters are more active in wet. Finer particles tend to be more active – they are floating longer in the water on the paper. They will be more affected by surface tension, and often will accumulate at the edges of puddles, creating an ‘edge’.
  • Even though floaters are stronger tinting, they have more hue shift and chroma loss as they dry.
  • Most of the modern pigments are floaters – azos, quinacridones, perylenes, etc. If you paint has a chemical-sounding name, it is most likely a floater. There are a few exceptions, so it’s always best to do the shot glass test.

Some Hybrid Characteristics

  • Hybrids have a portion that sinks and a portion that stays in suspension. Both components are the same hue.
  • Do not granulate
  • Almost always very opaque, unless seriously diluted.
  • Always staining, always strong tinters, very inactive
  • They tend to take over a mix, imparting their characteristics to the mix. Typically they are best used by themselves (or mixed with other hybrids), and applied with confident, juicy strokes. They are also often good as very thin washes.
  • Watch out – They tend to stick in your brush. Mix & clean thoroughly
  • The Cads and Indian Red are good examples of hybrids
  • Iron oxides will often seem to be hybrids, but close examination will find that the sediment is slightly darker than the solution portion. It is this difference that gives iron oxides their glow not found in any of the modern era replacements. They are subtly dual-toned.

Some Tips on Mixing Floaters and Sinkers

  • A sinker mixes well with a floater. Even 2 colors that would make mud in other wet media can produce a beautiful result in watercolor if it’s a sinker with a floater. [I discuss some of these mixtures in part 4 of my blog on ‘Many Ways to Gray’.] Imagine the pigment as ground gems. As you roll your paper around the settler is sinking and not following the water flow, while the floater is riding the wave. These are the most exciting mixes. A sinker can liven up an otherwise plain/dull floater (like Indanthrone, Dioxazine, Perylenes, etc)
  • Two sinkers can make an interesting mix, but be careful – the result can easily turn muddy and opaque. Test first. Be sure to let your test dry completely before judging it. And be sure to test the mixture at the same density you will be using it.
  • Three sinkers is begging for disaster
  • Watch out for Hybrids (Cads are best example). They don’t play well with many pigments. On the other hand, they can make unique mixtures. The only way to find out is to try them.
  • Mixing floaters will always yield a clean mix. Mix as many as you want, you will still have a clean mix.
  • Two or more floaters will yield a new color in the mix (it will appear that way), and the pigments will remain well mixed even after it dries on the surface. Whereas, a sinker will continue to have its own identity.
  • Strong-tinting pigments can be challenging to mix with a weak-tinter. Always start with the weaker tinting pigment and be very conservative when adding the strong pigment.

What’s the Use?

So how does categorizing a pigment as either a sinker or a floater help us select a particular paint and/or use it more effectively? Let’s answer this by taking a look at a few examples.

 

EXAMPLES

  • SMOOTH WASH: Suppose you want to execute a nice smooth wash. If you’re using a fast sinker, the pigment will sink immediately as soon as you brush touches the paper, leaving obvious brush strokes.  Sinkers are very difficult to move around after they are down, and trying to do so results in an overworked look. Floaters make better smooth washes.
  • EDGES: If you want a particular wash to have its edges accented, you will want to include a strong floater in the mix and use water to encourage it to go to the edges.
  • LIFTING: I often use a yellow ochre for the first layer in a soft portrait. It will be easy to soften edges of subsequent layers because of the lifting capabilities of the sinker underneath.
  • BRUSH ACTION: If you use a lot of strong brush action, you don’t want to work over a layer made with a dried sinker, since the fresh water will loosen and brush action will lift and disturb the sinker underneath.
  • SPECIAL EFFECTS: Some of the most interesting mixes will have a sinker and a floater. As the mix dries on the paper the sinker will go to the paper quickly, leaving the floater to move around with water and gravity.  The result is a vibrant mix that shows both the pigments.  This is a phenomenon that only occurs in watercolor.

Building a Watercolor Palette

If you’re looking to build a palette, you will undoubtedly discover there are many paints that have very similar colors. Why own two paints that are essentially the same color? This is a valid question, and if you are working in oils or acrylics, you probably don’t need to own both. But with watercolors, you many often want to take advantage of characteristics other than color.

For example, Viridian Green (PG 18) is almost exactly the same color as Phthalo Green, blue shade (PG 7).  But PG 18 is a sinker and granulator, whereas, the PG 7 is a floater.  PG 7 would be a good choice for executing a smooth wash, whereas the Viridian would leave streaks.  On the other hand, the Viridian mixed with a nice floater will give a vibrating result. A good example of this can be found in Daniel Smith’s ‘Moonglow’.  In this paint mix, Viridian is combined with Ultramarine Blue (both sinkers) and Anthraquinoid Red (PR 177) is the floater.  The resulting gray vibrates, since the Red separates from the settlers.

Author: John D McLaren
May 5, 2022