Introduction to Pumice Stone
Pumice stone is a porous, lightweight volcanic rock known for its high strength and resistance to chemical treatments. It is widely used in the textile industry, particularly in the stone washing process of denim fabric.
Stone Washing Process
Stone washing is a technique used to give denim garments a “used” or “vintage” appearance through varying degrees of abrasion. Traditional denim stone washing typically employs pumice stones to achieve a soft hand feel and desirable look. The oval and round shapes with rough surfaces of pumice stones act as an abrasive during the washing cycle, imparting different washing effects on denim fabric based on their shape, composition, hardness, and porosity.
Use of Pumice Stone
In the stone washing process, pumice stones scrape off dye particles from the surface of denim fabric yarns, resulting in a faded, worn, and bright appearance. Due to the ring dyeing of denim fabric and heavy abrasion during stone washing, the fading is more pronounced but less uniform. Stone washing makes denim garments more supple for comfortable wear.
Selection of Pumice Stone
To achieve the desired washing effect, it is crucial to select pumice stones with the appropriate hardness, shape, and size. For heavy-weight denim fabrics, large and hard stones are suitable, while smaller and softer stones are ideal for lightweight denim. The weight ratio of stone to fabric typically ranges from 0.5 to 3:1. The degree of color fading during stone washing depends on several factors, including the garment-to-stone ratio, washing time, stone size, material-to-liquor ratio, and load of garments.
Recycling of Pumice Stone
The stone washing process may last from 60 to 120 minutes, and pumice stones can be reused until they completely disintegrate.
Limitations of Pumice Stone
Despite the significant role of pumice stone in stone washing, there are limitations. Stones may cause fabric wear and damage to washing machines due to abrasion. Additionally, there may be environmental disposal issues with the grit waste produced by the stones.
Environmental Alternatives
To address these issues, alternatives to pumice stone have been introduced. Synthetic stones, made from abrasive materials like silicate, plastic, rubber, or Portland cement, offer advantages such as durability, reusability, and less damage to machines and garments. Perlite, a natural silicon rock that expands when heated, is another alternative that provides less damage to washing machines and results in a softer finish for denim garments.
**For those interested in pumice stone, readers can visit the Eco Stone Wash website at www.ecostonewash.com, or follow their Facebook page Ecostonewash for more in-depth information.