Contribución al estudio de la vida útil de las sábanas de algodón.

The influence of the polimerization degree (PD) of the sustrate on the behaviour of cotton sheets to repeated washings, carried out at different temperatures with or without sodium perborate, has been studied. The initial condition of the seet hardly influences the length of its useful life. This is due to the fact that rhe PD decreases at a faster rate when less is attacked the original material, so that -except in the mildest washings- the three sustrates examined show a similar PD from 100 washing or even before; the existing differences disappear sooner when the washing conditions are stronger. It has also been observed that an inadequate combinatien of the perborate concentration and the washing temperature may cause materials becoming useless after 20 washings. Other aspects studied in this paper are the evolution of the tensile strength and whiteness versus the number of washings.