Here’s some interesting texures you can make using watercolour paints. from top to bottom:
Alcohol – Drip some alcohol on the painted area and the paint will separate from the area. the dryer the paint is, I’ve found, the darker and crisper the edges of the seperated area of white will be.
Salt – Sprinkling Salt on the paint created a sandy texture. the longer you leave the salt there as it dries, the more the paint will spread but this works best the more semi dry the area is.
Blotting/Lifting – As an area dries, you can used water in your brush to blot areas back to white by making the paint spread away or you can use a dry brush to absorb or lift the paint from the area.
Stencils/erasing – While an area is semi dry, you can use paper or plastic shaped to remove the paint in a shape. I like using tape when i do this, shiny side down and sticky side up, this way you can touch it with the other end of your paintbrush to pick it up instead of trying to peal it away with your nails.
Sandpaper – This is hard to pull off in my opinion but is you use good, thick watercolour paper so you dont get holes and wait for the paint to be nearly dry like on the right rather than the left, you get a scratchy effect.
Wax – Use candles or wax crayons to make marks and shapes but drawing with the candle or crayon then adding the paint. Like on the left. You can go back after the paint dries and wax out more areas to keep that colour and then paint again like on the left to create layers.