Textile chemical processing solutions can be diluted using air in place of part of the water by forming foams. The basic types are stable and unstable foams . There are several common commercial applications of foam processing, notably carpet dyeing, coating operations (backcoating), foam dyeing and foam finishing as reported in references  and . Each type requires a different chemical system and mechanical arrangement for producing, handling, and applying the foam.
The claimed advantages for this method are water, chemicals and energy savings, since there is less water to be evaporated when drying the fabric   .
According to the literature consulted, foam processing on continuous equipment (e.g. backcoating), has the disadvantage that, when the production line stops, the foam must be disposed of. This can be very difficult, especially when stable foams (e.g. backcoating) get in the wastewater, producing suspended solids which are hard to treat and will not settle. Possible ways to destroy excess foam include spraying it on the heated plates or dry cylinders where it can be rapidly dried, scraped off and recovered as a solid waste for disposal. Prior to setting up a foam operation, it is important to plan for foam disposal by some method other than discharge to the process wastewater stream  .
References from reviewed literature:
In : J.S. Badin and H.E. Lowitt, The U.S. Textile Industry: An Energy Perspective, DOE/RL/01830/T-56, prepared by Energetics, Inc. for Pacific Northwest Laboratory, Richland, Washington, 1988
B. Smith, A Workbook for Pollution Prevention by Source Reduction in Textile Wet Processing, Pollution Prevention Pays Program, North Carolina Department of Environment, Health, and Natural Resources, Raleigh, N.C., 1988