Ecoline Brush Pens are filled with Ecoline Liquid Watercolour Ink. Ecoline ink offers artists a vibrant and rewettable fluid watercolour that is suitable for a range of artistic techniques. Their ink is transparent and dye-based and can be used to create washes of colour and detailed illustrations. These highly versatile pens can be used to create a vast range of marks. Use their fine tip for the smallest of details, or ustilize the side of the brush to create bold, sweeping marks.