Watercolour painting provides us with fantastic possibilities to create various textures. They can be achieved in many different ways with use of many different side components and equipment - in this article, I'll focus on salt textures. It usually takes time to get a handle of it - like everything else - but the outcome is definitely worth it.
Watercolour and salt
The three factors that determine the effects are the amount of water, amount of pigment and amount of salt, with the two first being the harder part. The more water you use, the more time it takes for the paint to dry and the more time the salt has to work - therefore the pigment will be pushed further away and you'll get bigger, paler spots between darker pigment borders. Less water will get you smaller, star-like bright spots - and salt won't have time to push the pigment too far before water dries, so you'll have untouched painted surfaces with the salty bright stains (or rather the opposite of stains) here or there.
Water and pigment
Kitchen salt is the most commonly used type and it works very well. How about experimenting a bit? Thick, coarse salt can make interesting effects when there's little water and lots of pigment. Coloured bathing salt, except behaving like the types used for food, will also leave colourful dots (and who doesn't like working with something that smells so nice). After your painting dries, carefully scrap the salt off the surface - you can use it again later, so simply stash it (I prefer keeping such salt in another box, not to mix it with the clean one).
The salt itself
Surely the basic effects are very nice themselves, but it can get boring seeing the same white undergarments of your paper. Try layering a thin wash or two (here's a lovely article on watercolour washes), wait for them to dry and then put your salted layer over - and your paper's undergarments are now less shiny white and more colourful. You can also paint over the salt textures - caution recommended, pouring too much water may blur the previous effects even a lot.
Take a look at the pictures below - some depict the effects I've already mentioned, some show other variations.
From left to right: very little water and lots of pigment with varied salt;
little water and lots of pigment (two colours);
a wee bit more water and lots of pigment.
From left to right: medium water and medium pigment, paper surface at an angle;
medium water and more pigment, painted over a thin base layer;
lots of water + lots of pigment placed at selective spots.
From left to right: medium water, medium pigment, thin brown layer selectively painted over;
pink coloured salt, a bit less water and medium pigment;
a bit less water with less pigment, painted over a light gradient base layer.
All the examples come from my own works. To view a whole painting, click on the picture to get to the link.