For many years the process involved washing-out the sizing, and then washing the denim in large commercial/industrial machines with either enzymes or stones, or both. The result was a finish which through abrasion and chemistry made a new product look old, worn, and comfortable.

Unfortunately with traditional "stonewashing", large, expensive laundry machines are abused by the same process which works on fabric, and basic denim can be abraded too much.

During the last ten years, alternatives to real stones (volcanic pumice) have been tested by all the major jean manufacturers. The goal has been to reduce the amount of maintenance required when using stones, and to achieve a softer finish. After years of testing, many are using various grades of perlite.

Perlite has been found to perform many of the same properties as stones. It produces a much softer, pliable finish, and it reduces substantially the wear on the machines. Perlite also gives a worn, finished look throughout the fabric and not just on the upper surfaces. In some cases it also has allowed a reduction in the use of enzymes which chemically attact the fibers and ultimately result in fabrics that wear-out very quickly.

Currently many grades of perlite are being used ranging in size from the largest horticultural grade to the finest grades (see either Finishing with Perlite) or Standard Gradations of Horticultural Perlite----Fine, Medium, and Coarse). Some manufacturers also use a very, very fine filtration grade similar in size and appearance to DE (ground, and milled diatomaceous earth).

The exact gradations of perlite used and the special enzymes chosen are considered proprietary process information by all the large finishing companies. And yet more and more stonewashing is being done every day with basic perlite both in this country and many others.