Salt: a technique that depends on paper sizing
Salt texture is the most imitated and least understood effect in watercolour. The stars and speckles people attribute to the salt are actually produced by the paper's internal sizing failing locally. Change paper and the same salt gives a completely different result.
Cobalt — Mid-value, semi-opaque, violet-leaning.
| Pigment | Parts | Hex |
|---|---|---|
| Cobalt Blue | 3 : 5 (60%) | #3B6FA8 |
| Indanthrene Blue | 1 : 5 (20%) | #2A3F6B |
| Cerulean Blue Chromium | 1 : 5 (20%) | #4E93B8 |
- Lay a saturated, glossy wash. Salt does nothing on a thin or drying wash — it needs water it can pull.
- Wait sixty to ninety seconds until the sheen has just left the surface.
- Scatter coarse rock salt first, from 30 cm, with your fingers. Coarse salt makes large, slow stars.
- Scatter table salt in a second area. Fine salt makes small, dense speckle and works faster.
- Leave one third of the panel unsalted as a control so you can judge the effect against plain pigment.
- Do not touch anything. Brushing salt off a wet wash embeds crystals and tears the sizing.
- Once bone dry — at least an hour — brush the salt off with a soft fan brush over a bin.
- Any crystalline rings left behind can be glazed over later, but only if the sizing survived the salt.
What the salt is actually doing
Salt crystals are hygroscopic: they pull water toward themselves and hold it while they dissolve. On a glossy wash, each crystal creates a small local drought beneath itself as it takes water in, and the pigment around it is drawn to the crystal. The pale star you see is pigment that has left.
The dissolved salt also attacks the surface sizing. On a well-sized 300 gsm sheet it makes clean crystalline rings; on a cheap or lightly sized paper it makes a torn, absorbed blotch that cannot be glazed.
Three grain sizes, three results
Coarse rock salt, 2 to 3 mm, dissolves slowly and produces large, well-separated stars over about eight minutes. Fine table salt dissolves fast and produces dense speckle over about two minutes. Flake sea salt sits between them and tends to produce irregular, elongated shapes.
Applying more than one grain size across the same wash gives a texture with two scales of detail, which is what makes the result read as a material rather than a gimmick.
The pigment must be willing to move
Salt only works with pigments that stay mobile while wet. Cobalt blue and indanthrene blue both have fairly heavy, granulating particles and respond strongly. Quinacridone and phthalo pigments are so staining that the salt cannot pull them far, and you get faint dotted marks instead of stars.
Cobalt blue at three parts to one part indanthrene blue gives a deep, slightly violet blue. A single part of cerulean keeps the darker mix from looking inky under the salt.
What matters
- Salt depends on paper sizing: 300 gsm well-sized stock gives rings, cheap stock gives torn blotches.
- Scatter coarse salt first, then fine; two grain sizes give two scales of detail.
- Wait 60 to 90 seconds after laying the wash — salt does nothing on a dry or thin wash.
- Only mobile, granulating pigments respond; staining pigments give faint dots instead of stars.
Handling note — Technique notes only. Salt and pigment residue should be swept up and disposed of rather than washed into a domestic drain; follow the manufacturer's safety data sheet.