Artists for many years have appreciated the qualities of the Langton. The paper is colour stable, mould made and acid free. The best watercolour papers are acid free to prevent the deterioration of paints and to preserve the integrity of the paper over time.- 12 sheets 300gsm (140lb) acid free watercolour paper. (Hot Pressed)The surface of Hot Pressed paper is made very smooth by passing the sheet through hot metal rollers. It is popular with those painters who like detail, do not utilise granulation particularly and with illustrators and designers who require flat artwork for reproduction.