User:Jahydenm/Stone washing

Stonewashed jeans are jeans that have been treated to produce a faded, worn appearance. This is usually accomplished either by washing the jeans with pumice in a rotating drum, or by using chemicals to create the appearance without the use of a rotating drum. Pumice stones act as sandpaper on jeans, removing some of the dyes present. The expanding cost of importing pumice stone from Italy, Greece and Turkey led to extensive mining of pumice deposits in California, Arizona, and New Mexico, triggering a negative response from American ecologist groups. The reduction of pumice usage and the growing disposal of its chemically-tainted residue triggered a search for novel methods, notably the use of alternative abrading materials or machines and the use of cellulase enzymes. The use of pumice stones also made the stone washing process harder to control, contributing to the method's decline. Too much of this pumice stone could damage the buttons or waistbands on jeans. Stonewashed jeans were a popular 1970s fashion trend, before commercial acid wash denim (discussed below) was introduced in the 1980s. In the 2000s, stonewashed jeans were heavily distressed, with pre-made holes, frayed edges and extensive fading caused by sandblasting.

Claude Blankiet with American Garment Finishers from Texas promoted the use of cellulase enzymes in the finishing industry. The use of cellulase enzymes to modify the appearance of jeans is commonly referred to as "biostoning." Cellulase was already used in the paper pulp, food processing industry and currently in the fermentation of biomass for bio-fuel production. Cellulase is primarily isolated from fungi, bacteria and protozoans that catalyze the hydrolysis of cellulose. Various fungi have varying effects on the look of the denim that is being modified. Since the enzyme decomposes cellulose fibers this enhanced the characteristic appearance that the jeans have been abraded with stones (and eliminated or considerably reduced the usage of natural pumice stones). The use of biostoning allows for the selective loosening of dye particles from jeans. Buttons and other seams are less likely to be affected when biostoning is at play. Selecting the most suitable type of enzyme and their application for ageing jeans was the key to success. Along with the type of enzyme, the temperature at which the biostoning process occurs is also important. If temperatures are too low, the process proves to be less efficient. Similarly, if the biostoning process occurs in temperatures that are too warm, the denim can appear to be too faded. American Garment Finishers used a new cellulolytic agent patented in 1991 by Novo Nordisk from Denmark because of its safer effect on cotton fiber. Other finishers used an acid side Trichoderma fungi enzyme, cheaper and faster acting, but resulting in excessive fabric tear and a back lash because jeans pockets were lifting off. The cellulase enzyme that is used to biostone jeans was isolated from the fungi, Trichoderma reesei.