Why does my watercolour dry with hard cauliflower edges?

Blooms — also called backruns, cauliflowers or blossoms — are the fault that makes people give up on watercolour, and they feel random. They are not. Water always flows from wet to less wet, so the moment your brush is wetter than the paper, water spreads outward, carries suspended pigment with it, and deposits it in a ring where it stops.

Step by step

1. Learn to read the three stages of a wash.Shiny and wet: a pool with visible sheen. Damp: matt but still cool to the back of a finger, the dangerous stage. Dry: room temperature to the touch. Blooms happen almost exclusively when you touch the damp stage with something wetter.
2. Match the wetness of your brush to the paper.Into a shiny wet wash, a wet brush is fine — the paint diffuses smoothly. Into a damp wash, only a drier brush than the paper will behave. Onto dry paper, anything is safe because there is nothing to flood.
3. Blot your brush before touching a wash.One touch on a sponge or a piece of kitchen paper takes a loaded brush from wetter than the paper to drier than it, and that single habit prevents most blooms.
4. Finish a wash and then leave it alone.The urge to tidy an edge or fix a patch while a wash is drying causes most of them. Once the shine has gone, do not touch it until it is completely dry.
5. Do not tilt or move the board while it dries.Moving a drying wash lets pooled water run back into drier areas, which is the same mechanism. Lay it flat and leave it.
6. Work faster and with a bigger brush for large washes.A wash that takes too long to lay starts drying at one end while you are still working the other, which guarantees the damp-into-wet collision. Use the biggest brush you can and commit.
7. Use them deliberately when they help.A bloom is exactly what foliage, clouds, rust, lichen, rock texture and weathered surfaces look like. Many watercolourists cause them on purpose by dropping clean water into a damp wash. Learning to control the effect is more valuable than learning to avoid it.
8. Accept the ones you cannot remove.Watercolour rewards a light touch and punishes correction. A picture with one bloom in it usually looks better than one that has been scrubbed twice trying to remove it.

Tips

• Humidity matters more than people expect. In a damp British room a wash stays workable for far longer than in a heated one, which changes all your timings.
• A hairdryer on low, held well back, shortens the damp stage and reduces the window in which you can cause damage. Do not blast a still-pooled wash — you will drive the pigment about.
• Staining pigments such as phthalo blue leave far more behind after any attempt at removal. Non-staining pigments lift much more cleanly and are more forgiving for beginners.
• Heavier paper stays wet longer, which is helpful for wet-in-wet work and less helpful when you want to move on.

Common mistakes

• Touching up a nearly dry wash — It is the exact condition that produces a bloom. If it looks matt, walk away.
• Overloading the brush — A brush carrying more water than the paper is holding will always flood. Blot before every touch into a working area.
• Trying to remove a bloom while the paper is still damp — Scrubbing damp paper damages the surface, and the disturbed area will take paint differently for the rest of the painting.

If it doesn't work

Questions people ask