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PUMICE

PUMICE
  1. Pumice Stone is a volcanic rock that consists of highly vesicular or perforated volcanic glass. Pumice Stone is created when super-heated and highly pressurized rock is violently erupted from a volcano. The unusual foamy configuration of pumice happens because of simultaneous rapid cooling and rapid de-pressurization.
  2. Pumice Stone commonly originated from Indonesia and Turkey.  Different sizes of Pumice Stones are available. such as:  2-5 cm which known as small Pumice Stone.  3-5 cm which known as medium size Pumice Stone. And 5-7cm which is known as Large size Pumice Stone. The hardness of Pumice Stone in Mohr scale is 6.  The melting temperature of Pumice Stone is 15000˚ C.  pH value is 8 .  The density is 2.313g/cm3.
  3. Some points should be followed during selecting pumice stones for stone wash,  Pumice stone should be selected according to the end product and required amount of effect needed on the garments.  Large and hard stones are suitable for heavy weight garments.  Smaller and soft stones are suitable for light weight garments.  Ratio of stone weight and garments weight is – [{(0.5 to 3)/1} kg].  moisture content of pumice stone should be less than 5%.  Surface properties of pumice stone should be less than 5%.  Abrasion loss of pumice stones should be 35%.  Apparent density of pumice stone should be 0.5-0.75gm/cm3.   One of such washing is known as stone wash. In stone-washing the worn-out look is given purposely.  The fabric is washed along with pumice stones. The stones and denim are spun together in large industrial washing machines. The longer they are spun together lighter the color of the fabric with better contrasts would result.  The time duration of this procedure is set beforehand so as to avoid the tear and wear of the fabric.  Thereafter, the fabric undergoes various other processes of rinsing, softening and finally tumble-drying.  These stone-washed fabrics are used for different purposes — garment making as well as for upholstery purpose.
  4.  Advantages of Pumice Stone:  Desired vintage effect on garments can be easily achieved by using pumice stones.  Washed garments can achieve more soft effect by using pumice stones. The worn-out look is given purposely.




COMERCIAL PUMICE SIZES







One of the oldest building materials known to mankind is pumice which was used extensively by the ancient Greeks and Romans in the construction of aquaducts, amphitheaters, basilicas, baths and vaults.The famed Pantheon, built in Rome in 27 B.C., still affords proof of the durability of pumice. Pumice is a textural term for a volcanic rock that is a solidified lava typically created when super-heated, highly pressurized rock is violently ejected from a volcano. This unusual formation is due to the simultaneous actions of rapid cooling and rapid depressurization. The depressurization creates bubbles by lowering the boiling point of the lava.The simultaneous cooling then freezes the bubbles in the matrix.

The general chemical analysis of pumice is:

SiO2……………………………..60-75%

Al2O3……………………………13-17%

Fe2O3…………………………..1-3%

CaO………………………………1-2%

Na2O-K2O……………………..7-8%

TiO2……………………………..Trace

SO3………………………………Trace

The high percentage of silisium oxide gives the pumice it's abrasive quality, thus it exhibits a chemical composition which can easily erode steel.The Al2O3 in the structure makes the pumice highly resistant to fire and heat. Na2O and K2O are the minerals which give the pumice the reaction sought after by the textiles industry. As a result of acidic or basaltic activity,the resulting pumice is also of acidic or basaltic nature.Acidic pumice, known simply as pumice, is white in colour, however due to the density of acidic magma being much lower than that of basaltic, its’ specific weight is also much lower, at about 0.5-1 gr/cm3. The high level of SiO2 gives this pumice it's white colour.

The physical properties of pumice are governed by the extremely cellular structure of the matrix. These cells are independent of each other, which means that the level of sound and heat conductivity are both extremely low. The hardness of pumice is approximately 5.5-6 on the mohs scale. It does not contain crystalised water in it's structure. It is chemically inert and possesses about 75% silisium oxide. Due to the microscopic size of the pores, which make up about 85% of the pumice grain volume, pumice is an extremely light rock which is able to float on the surface of water for a long time.

Pumice is widely used as an industrial abrasive where the protection of the surface is critical. Various grades and blended grades of pumice are used to: Polish glass, clean and texturize electronic circuit boards, clean lithographic plates, prepare metal surfaces for electroplating, buff leather and fine furniture woods, act as a tumbling media for things like buttons, cutlery, small metal or plastic parts.The mild abrasive quality, benign chemical nature, and ability to refine pumice to fine dust make it an ideal additive for cleaning, polishing, and exfoliating products.