PEPIN Marker Colouring Books contain 16 sheets of superior acid-free bleedproof paper, printed with exciting and intricate designs. The printing is done in very light lines, so that the printed outline will not or hardly be visible after colouring. The 150 gsm paper is made to our specifications to be suitable for alcohol and non-alcohol based felt-tipped pens and all types of markers. However, other techniques can also be used. Paper from responsible sources, acid-free, colourfast and age resistant; the coloured sheets can be framed and displayed without the risk of rapid deterioration provided that high-quality, colourfast markers have been used.