iMerino
Stain Resistant
Stain Resistant
The physical and chemical structure of the merino fibre works to resist stains and release dirt more easily during laundering.
Low Surface Energy
The merino fibre has a very thin, waxy, lipid coating chemically bonded to the surface. This bonded layer extends over the overlapping scales on the surface of the fibres and cannot be easily removed by scouring, washing or processing. A consequence of this is that merino fibres have a naturally low surface energy. The accompanying table shows that the surface energy of merino is lower than cotton, nylon or polyester and is comparable with the hydrophobic surface of polypropylene. This means that water droplets touched lightly on the surface of merino will bead and roll off before being absorbed into the fabric. This allows time for liquid spills to be wiped from a merino fabric before they can cause permanent staining (Fig 1).
Low Dry-soil Pick-up
The low surface energy of merino also reduces the degree of dry-soil pick-up compared to most other fibres which is particularly important for floor coverings. The soiling of carpets made from different fibres is compared in Figure 2. This clearly demonstrates that merino retains less soil after vacuuming than either nylon or acrylic fibre.
Good Soil-release During Laundering
An important aspect of appearance retention for apparel is the ability of a fabric to release soil during laundering or dry-cleaning. It is well known that soil removal is generally more difficult from hydrophobic fibres such as polyester and can lead to the dulling of fabrics after washing and dry-cleaning. This phenomenon, called greying, is due to accumulation of dry and oily soil on the surface of fibres. Although the surface of merino is hydrophobic under ambient conditions, the fibre readily absorbs moisture and swells in the wash to give a hydrophilic surface that facilitates soil release. Modern detergents also include components to assist soil-release and soil-release finishes are also available for fabrics to enhance the removal of oily and dry soil during laundering.
Stain-resist Treatments
In recent years, stain-resist treatments have become popular for both apparel and floor coverings. The aim of these finishes is to eliminate residual staining of a textile that has suffered spillage of food and liquids. In carpets this is achieved by restricting diffusion and retention of acidic stains (e.g. food and drink colorants) into the fibre through a stain resist (stain-blocker) layer applied to the fibre during dyeing.
Fluorochemical Finish
By further lowering the surface energy of the merino fibre, fluorochemical finishes impart resistance to water and oily-based stains and are extensively used for corporate apparel and upholstery fabrics that are difficult to wash. Recently developed fluorochemical finishes have excellent durability to laundering and dry-cleaning and facilitate soil release. Treated woven and knitted goods can thus meet stain and water repellent performance standards for easy care products without the need for additional stain blocker chemicals.
Summary
Merino's natural low surface energy and the availability of modern finishes make merino garments stain-resistant and easy-to-clean with enhanced appearance retention throughout their life cycle.
Further Reading:
- Simpson, W.S., (2002) Chemical processes for enhanced appearance and performance in Merino: Science and technology in Simpson, W.S. and Crawshaw, G.H. (Ed.), The Textile Institute, CRC Press: Cambridge, England, pp. 215 324.
- Holme, I., (2003) Water-repellency and water proofing, in Heywood, D. (Ed.) Textile Finishing, Bradford, UK: Society of Dyers and Colourists, pp. 135-213.
- Pailthorpe, M. and David, S.K., Anti-static and soil-release finishes, in Heywood, D. (Ed.) Textile Finishing, Bradford, UK: Society of Dyers and Colourists, pp. 308 336.
