What is granulation in watercolour?

Granulation in watercolour is the speckled, grainy texture you get when pigment particles settle into the tiny hollows of the paper instead of staining it evenly. It is strongest on rough paper and with certain heavy pigments. Easel by Zaweba, a free natural-media painting studio, simulates granulation on rough paper, and it also has a granulation medium for when you want more.

Many painters love the effect. It gives skies a soft, textured depth, makes stone and sand look gritty and real, and adds a handmade quality that a perfectly flat wash can never have. Others avoid it for smooth portraits. Either way, knowing why it happens lets you choose.

Why some washes granulate

Watercolour paint is pigment suspended in water with a binder, usually gum arabic. As a wash dries, the water evaporates and the pigment has to go somewhere. Fine, light pigments tend to stain the paper fibres evenly. Heavier, coarser particles sink and gather in the dips of the paper's surface, leaving the ridges paler. That uneven settling is granulation.

Several things make it stronger: a rough paper surface with deep hollows, plenty of water so the particles can move, a wash left alone to dry rather than brushed over, and colours known for it. Mixing two pigments that settle differently can also make one separate from the other, which gives a lovely mottled look.

Granulation in Easel

In Easel watercolour flows, blooms, granulates on rough paper, lifts with a clean damp brush and dries with darker edges. Version 1.1 added rough watercolour paper to the surface list, alongside cold-pressed and hot-pressed. Those three are the classic watercolour paper surfaces, from the deep tooth of rough to the smooth face of hot-pressed.

To see granulation, start a picture on rough watercolour paper. Load a large brush with plenty of water and colour and lay a wash across the paper. Then leave it. Fiddling with a drying wash smooths out the particles. A wash dries in about 20 to 30 seconds of real time, and the drying speed slider runs from 0.25 to 4 times, so slowing it down gives the pigment longer to settle.

Repeat the same wash on hot-pressed paper and compare. The difference between them is the best lesson in granulation there is.

Granulation medium

Easel's mediums and additives include a granulation medium, along with gum arabic and ox gall. In real painting, granulation medium is added to a wash to encourage pigment to separate and settle even when the colour or paper wouldn't normally do it. Try it on a sky, a stone wall or a beach. Gum arabic and ox gall change how paint behaves in other ways, so they're worth exploring once you know what plain watercolour does.

Where to use it and where to avoid it

Granulation suits textured subjects: weathered wood, rock, sand, old walls, stormy skies, distant hills. It also works beautifully in loose, atmospheric landscapes where texture does some of the describing for you.

Keep it out of passages that need to look smooth, such as skin, clear skies at the horizon, polished metal or glass. Use smoother paper there, or paint those areas with less water and more control.

Learning to read your own washes

Once you know what granulation is, you'll see it everywhere in watercolour painting, and you'll start to plan for it. Practising in Easel by Zaweba lets you try the same wash on different papers, with and without medium, as often as you like, so you learn which combinations give the texture you want before you buy the paint and paper.