Fig. 1

Fibre based matt test photographs before and after ageing at 50 °C and 70% RH and 50 °C and 90% RH. First row left to right: well processed un-aged, aged 50 °C and 70% RH, aged 50 °C and 90% RH, second row left to right: corresponding versos of row one, third row: insufficiently washed un-aged, aged 50 °C and 70% RH, aged 50 °C and 90% RH, fourth row: corresponding versos of row three. Two of the samples are cut to allow direct comparison of the same photograph