PVA  sponge is a synthetic sponge essentially composed of Polyvinyl Alcohol.  It possesses a three dimensional open cell structure similar to that of natural sea sponges.  All of its cells are interconnected, not independent.  Major advantages of this physical structure are its high filtering efficiency, its ability to be reused after cleaning, and its impressive retention and wicking properties.

PVA  sponge will absorb up to 12 times its dry weight in water.  When saturated with water, it becomes flexible and soft like natural sea sponge.  The wet volume is about 20% greater than the dry volume.  PVA exhibits mechanical strength and abrasion resistance equal to or greater than any other synthetic sponge material.  Pore size and shape can vary to meet specific applications.  Wet PVA sponge will withstand temperatures to 90 degrees C without plastic deformation.
PVA is pure white. It can be pigmented in any color and to a high degree of color-fastness.

During the manufacture of PVA sponge, a water soluble porous structure is chemically insolubilized. The material will withstand the action of dilute acids, strong alkalis and solutions of common detergents.  Some detergents of the "sulfonate" category (over 5% strength) will slowly swell and weaken the sponge.  Organic solvents do not, as a rule, effect the sponge unless they are water-miscible and are applied mixed with 30% - 60% water.  In that case the sponge will swell and be weakened.  Thorough washing in water will return the sponge to its original state.  PVA is also not compatible with Nickel Sulphate solutions.
PVA sponge behaves in water as a negatively charged colloid and will strongly adsorb metallic cations such as copper or iron.  In fact, it acts like an ion exchange resin in this respect.  It also has strong affinity for cationically charged organic ions of the quaternary ammonium type.
PVA sponge, itself, will neither support the growth of bacteria nor molds, nor will it destroy those organisms.  Foam packaged wet should be treated chemically to inhibit bacteria or mold growth.
Rust stains may be removed in the same way; as they are from cotton using a solution of oxalic acid, or citric or tartaric acid.  Sodium hypochlorite solution (domestic bleach) degrades the sponge.