Adjusting granulation

I normally use a lot of granulating pigments, but sometimes I’d like to coax a bit more out of them, and other times, I’d prefer to have less granulation. Is there any way to adjust granulation? Yep. Here are some ideas to try.

First, what is granulation?

For those new to watercolor, granulation (a.k.a. sedimentation) is the speckly or mottled appearance produced by some watercolor pigments as they dry. Some common examples: 

• cobalt violet, cobalt blue, cobalt turquoise/teal, and cobalt green
• ultramarine violet, ultramarine blue-violet, and ultramarine blue
• cerulean blue
• raw sienna & burnt sienna
• viridian

Some granulating pigments are more granulating than others.

Also, manufacturers can somewhat enhance or diminish the amount of granulation of a particular pigment by how they grind the pigment and formulate their paint.

Ways to enhance granulation

Some paint brands emphasize granulation 

Different manufacturers target different tastes with their color lines, so people who love a lot of granulation often gravitate to brands that try to enhance their granulating pigments. Some to try: Daniel Smith, M. Graham, and Stephen Quiller’s signature line from Jack Richeson. Daniel Smith has a large selection of unusual mineral colors (which are often granulating).

However, there are plenty of lovely colors with lots of granulation in other color lines, too, so trying different brands is an expensive, and rather scattershot, way of enhancing granulation, but it’s worth keeping in mind as you choose paints.

Try a different type of paper

Within a given brand and weight of paper, rougher paper shows more granulation. So, 140-lb Arches Rough will show more granulation than 140-lb Arches Cold-Pressed, which will show more granulation than 140-lb Arches Hot-Pressed. 

But other characteristics of paper (especially absorbancy) also affect granulation, so there’s no simple rule. Sometimes a paper that is smoother promotes more granulation than a rough paper of a different brand. There are too many types of paper for me to test them all and report how they affect granulation. But one paper I use sometimes—Saunders Waterford—seems to promote more granulation than other papers that feel even rougher, so that one might be worth a try if you want more granulation. 

Slow down drying 

Granulation develops slowly as the paint dries, so one of the best ways to enhance granulation is to slow down the drying of your washes. 

Increasing the humidity in your studio by using a humidifier helps, especially in arid climates. But a simpler method is to thoroughly wet the back of the painting before you start painting. When I’m doing this, I usually just wet the entire back and let the paper stick to the support by surface tension. 

Use plenty of water to wet the back, and allow a little time for the water to be absorbed and the paper to flatten out. The water you add to the back slows drying of the wash, but does not dilute your wash or result in soft edges (as it would if you added it to the front surface).

One caution: If you leave the paper to dry with a lot of water still on the underside, you may get blooms along the outer edge. You can’t use a hair dryer to prevent blooms, because you’re trying to let it dry as slowly as possible. Instead, wait just until there is no longer any visible water on the front, then carefully pick up the painting and lay it on a dry surface to finish drying. The excess water mostly stays behind on your painting support. 

Note: Even better for preventing unwanted blooms along the edge is to transfer the painting to one of those “pee pads” for training puppies (like these). Unlike a towel, they immediately trap liquids under the surface layer, which stays mostly dry to the touch, so you don’t smear wet paint around. 

(They’re disposable, but for painting, you can hang them up to dry and re-use them. I usually get at least 6 months’ use out of each one.)

Adding a contrasting, non-granulating color

This is the trick behind Schminke’s “super-granulating” colors. Each of those colors combines a granulating pigment with a contrasting non-granulating color. As the mixture dries, the granulating color collects into little dots, as usual. The non-granulating color tints the paper in between the little dots. There’s not actually more granulation, but since the paper is now tinted a contrasting color, the granulation becomes a bit more noticeable. The more color contrast, the more noticeable the granulation becomes, but even a little can be a nice subtle enhancement. 

Choose a fairly transparent color for the contrasting non-granulating color. Opaque colors sometimes float on top of both the paper and the speckles of granulation, which mutes the effect. 

What about granulation medium?

This works, but for most pigments, the pattern of granulation it produces is different from the pattern you get with most naturally granulating colors. 

However, it’s the only way I know of to get granulation out of pigments that don’t granulate naturally. I tend not to use it much because it’s not a pattern I often find a use for. But that’s just me. You might love the look, or have the perfect situation to use it. 

Ways to minimize granulation

Substitute a non-granulating paint (or paint mixture) in a similar color

You may not be able to find an exact match for brighter colors, but many of the washes we actually use are somewhat neutralized. So, instead of trying to exactly match the granulating color, just worry about trying to match the target color you’re trying to mix. That’s often easier. 

For example, the phthalo blue red shade (below left) is close in hue to the cobalt blue on the right, but slightly less saturated. If you were using the cobalt blue to cool a skin tone and wanted a non-granulating substitute, it wouldn’t matter that the phthalo blue is a little less saturated. You’d just be using it to tone down a fairly neutral color, anyway. 

Even for a blue sky, cobalt blue is often a bit too saturated, so many people add a tiny touch of raw ochre or burnt sienna to slightly neutralize cobalt blue when using it for a sky. So it’s not a problem that the phthalo blue is not as bright. 

Use a hair dryer

The best way I know to minimize granulation is to use a hair dryer to speed up drying. When you do this, it helps to gently agitate the wash by wiggling the hair dryer rapidly, while moving quickly and evenly over the entire surface. 

The photo below shows a swatch of cobalt teal dried with a hair dryer on the left, compared to a swatch painted on dry paper (middle) and a swatch where we wet the back first (right). This shows how we can manipulate the same pigment to have no granulation, or the usual amount, and more than usual, by manipulating the drying speed.

Mix in a bit of white watercolor (or gouache)

If you are laying a wash over a larger area, or your climate is very arid, you may have a hard time getting back to dry it with a hair dryer before some granulation starts to occur. Another trick to minimize granulation is to mix in a bit of white watercolor (or gouache). Each pigment (and brand) is a little different, so you’ll need to do a bit of testing to figure out how much white to add, but it usually doesn’t take very much. You can use either titanium white or zinc white (Chinese white). 

That’s it for my bag of tricks for adjusting granulation. Do you know another?

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