Watercolour Aquarelle Pencils
Watercolour Pencils appear at first to be normal coloured pencils, but when water is added to them, they give the beautiful look of watercolours.
They might seem tricky to use at first, but when used correctly, the end result is wonderful!
You can use watercolour pencils in adult colouring books but it is not advisable for small details such as eyes and tiny designs. Also, watercolour pencils are not suitable for certain types of paper, such as printer paper because you are adding water to the colours.
Shade a layer of the colour that you want for your background (if you want it to be light and soft, shade lightly, if you want it to be vivid, press hard, etc). Using a flat brush, brush water onto the background in a certain direction. Applying a consistent amount of pressure to the brush, using a consistent water and applying a consistent amount of pressure and pigment will obtain a flat background. This technique can be applied to gradient effects.
http://www.wikihow.com/Use-Watercolor-Pencils