Importance of the Removal of Sebum Soil from Cotton Undershirts in Japanese Home Laundry

Abstract

To determine the most troublesome aspect of Japanese home laundry, a fact-finding survey and a series of uncontrolled wear-and-wash tests were carried out at 69 households selected at random throughout Japan. Of clothes washed during the period of the survey, 71 % were 100 % cotton fabrics and 14 %, cotton-synthetic blends. 1.6 kg of the clothing was washed in detergent solution having 57.1 ppm water hardness as CaCO3 at ambient temperature. The average number of wear-and-wash cycles was from 13.9 to 14.7 over a period of 40 days, depending on the type of clothing.Cotton undershirts use in the test were washed as mentioned above, using a spray-dried powdery heavy duty detergent containing no enzymes or special additives. By measuring the amounts of residual soil in cotton undershirts from 25 households, 27.4 mg of sebum/g of cloth and 3.3 mg of protein/g of cloth on the average were obtained from the shirts prior to the final washing at the end of an average of 14.7 wear-and-wash cycles of home laundry. The undershirts after the final washing contained 17.0 mg of sebum/g of cloth and 0.9 mg of protein/g of cloth on the average. Prior to and after the final washing, the amounts of residual sebum in cotton undershirts were more closely related to the number of wear-and-wash cycles than the amounts of residual protein. With increase in accumulated sebum, b values of cotton undershirts also increased. The amount of residual protein on clothing was not correlate to the b values of the clothing to the same extent as was the amount of residual sebum. Cotton undershirts soiled by sebum is thus shown to be one of the most difficult aspects of Japanese home laundry.