Sponge (material)

Artificial fiber sponge: Polyurethane sponge combined with scouring pad.

Animal fiber sponge: A Greek natural sponge.

A sponge is a tool or cleaning aid made of soft, porous material. Typically used for cleaning impervious surfaces, sponges are especially good at absorbing water and water-based solutions.

Etymology

The word comes from the Greek word σπόγγος (spongos).^[1]

History

The first references of sponges used for hygiene dates from the Ancient Greece . Competitors of the Olympic Games bathed themselves with sea sponges soaked in olive oil or perfume before competing. In the book Odyssey by the Greek poet Homer, the god Hephaestus cleans his hands, face, and chest with a sea sponge, and the servants in the Odysseus palace also used sea sponges to clean the tables after the meals the suitors of Penelope had there. The Greek philosophers Aristotle and Plato also mentioned sea sponges in both scientific and historic contexts in their works.^[2][3] Ancient Greeks also used sea sponges tied to sticks as toilet paper, and washed them with sea water.^[4]

Ancient Romans also used sea sponges extensively for hygiene and other uses. The belief that sponges had therapeutic properties led to its usage in medicine for cleaning wounds and treating disease.^[2]

Sea sponges were used as tampons by females throughout history and are still used as a cheaper and more eco-friendly alternative to fibre ones.^[5] However, researchers do not recommend using sea sponges as tampons, as they may contain dirt and microorganisms, especially if poorly sanitized.^[6][7]

In the New Testament, a Roman soldier offers Jesus Christ a sponge soaked in vinegar on the tip of his spear (some versions say staff) for Jesus to drink during his crucifixion, as an act of mockery.^[3][8][9]

Synthetic sponges were made possible to be manufactured only after the invention of polyester in 1941 and the commercial production of polyurethane foam in 1952.^[10][11]

Material

Synthetic sponges can be made of polyester, polyurethane, or vegetal cellulose. Polyurethane is used in polyester sponges for their abrasive side. Polyester sponges are more common for dish washing and are usually soft and yellow.^[12][13]

Vegetal cellulose sponges made of wood fiber are more used for bathing and skin cleaning, and are usually tougher and more expensive than polyester sponges. They are considered more eco-friendly than polyester sponges as they are biodegradable and made of natural materials.^[12][14]

Harboring bacteria

thumb|right|200px|Bacteria from a kitchen sponge Because it is primarily made of wood fiber, a cellulose sponge can be a medium for the growth of harmful bacteria or fungi, especially when it is allowed to remain wet between uses.^[15]

Cleaning

Several methods have been used to clean sponges. Studies have investigated the use of the microwave to clean non-metallic domestic sponges that have been thoroughly moistened. A 2006 study found that microwaving wet sponges for two minutes (at 1000 watt power) killed 99% of coliforms, E. coli, and MS2 phages, but Bacillus cereus spores required four minutes.^[16] After some fires were caused by people trying to replicate the results at home, the study's author urged people to make sure their sponges were wet.^[17] A 2009 study showed that the microwave and the dishwasher were both effective ways to clean domestic sponges.^[16]

In economy

Caribbean and Mediterranean developing countries are the largest sponge exporters, whereas the largest importers are developed European and North-American countries. Tunisia is the world's main sponge exporter, exporting 90% of its sponge production. France is the main importer, being supplied by Tunisia, but France's sponge demand has fallen in recent years.^[18]

Gallery

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  Natural sponges for sale in Crete

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  Plant fiber sponge: A luffa sponge whose coarse texture helps with skin scrubbing and exfoliation

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  A Luffa aegyptiaca sponge section magnified 100 times

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  A close-up of one corner of a urethane abrasive sponge with a top layer used for more intense dish scrubbing

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  A close-up of a synthetic sponge's openings

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  A souvenir made out of an artificial sponge

See also

• Dishcloth
• Ethylene-vinyl acetate – material that craft foam is made from ethylene-vinyl and acetate
• Luffa aegyptiaca
• Sponge metal

References

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