PVA
Rigid foam made from cross-linked Polyvinyl Alcohol, which becomes soft and flexible in the presence of water.
Originally found during the second world war when they were looking for a substitute for balsa wood to use in the construction of aeroplanes. Due to balsa wood main supplier been America which was imported by ship, which at that time the Germans were sinking most of them with their submarines.
PVA sponge was one of the materials that was investigated as it has the favourable characteristics of being lightweight and very strong which made it a very promising material. But it had one major disadvantage that when in contact with water it became lovely and soft and flexible, which lead to it only been used for planes in the Sahara and Arizona desert and being removed from the top secret list.
The founders then took PVA sponge into its more commonly known area as a extremley good cosmetic and bathing sponge. Due to its high absorbency and resiliance it is by far a superior material than your average square sponge.
Cellulose Sponge Characteristics
- Rigid when dry, soft when in the presence of water.
- Hydrophilic.
- Holds up to 12 times its dry weight.
- Doesn't scratching.
- Mechanically strong, abrasion resistant.
- Non-aging, long lasting.
- Natural colour: white.
- Excellent colour fastness.
- Burns without toxic gases.
- Good chemical resistance.
- Pore size variable between 200 and 1500 microns.
- Warm water softens sponge faster.