Textile Finishing and Fabric finishing is very important terms in textile manufacturing area. We need some special task with textile material to meet the buyer requirement. We know that natural fibres as well as textile fabric manufactured with natural fibre absorb the water. So it easily passes water with their surface. If we want to protect passing water or making the water proof fabric surface, we need to do some special treatment to surface of the fabric. This could be known as water proofing finishing. This is similar for Soil and Water Repellency finishing. The term water repellent should not be confused with the term waterproof Water-repellent fabrics resist penetration by water but are not completely waterproof. Such fabrics represent a practical alternative to fabrics that keep out water and air.
For a fabric to be truly waterproof, it must be completely sealed with a substance that is insoluble in water. The familiar rubber coated garb of police officers and firefighters is a good example. Modern waterproofing materials include the vinyl resins, which do not oxidize and crack as readily as rubber. Synthetic rubbers are also more durable to outside influences than natural rubber. The fabrics used in most of today’s waterproof materials are cotton and nylon. The latter, coated with vinyl resins, has largely superseded the heavy canvas tarpaulins used to protect merchandise in transit. A fabric that is waterproof allows no water to penetrate from the surface to the underside. Coatings made from rubber or synthetic plastic materials can create fabrics that are completely waterproof; however, these fabrics tend to be warm and uncomfortable because they create a barrier that traps air and perspiration close to the body.
The dilemma of providing protection and comfort was resolved by the development of fabrics that are described as waterproof and breathable (WP/B). The general principle behind these fabrics is that they keep out water from rain and snow but allow the passage of moisture vapor from perspiration. They are promoted for use in outdoor clothing and for active sports. One of the first of these products was Gore- Tex, made by placing a membrane of fluoropolymer underneath a layer of outer fabric. The membrane is porous.
The pores are smaller than a drop of water that contains many water molecules, but they are larger than a molecule of water vapor. This structure keeps out rain but allows moisture from perspiration to escape.
The success of Gore- Tex has led to the production of other products using similar principles. Many of these use polyurethane coatings with microscopic pores. Sympatex, a polyester membrane for lamination, is nonporous but breathable. A charged outer surface attracts polar water molecules which are drawn through the membrane. Also helping to “push” moisture vapor through is the high vapor pressure on the body side (Sympatex 1988).
Soil and Water Repellency finishing:
Soiling results when a textile comes into contact with soiled surfaces or with air- or waterborne soils. Soil is retained either by mechanical entrapment of soil particles within the yarn or fabric structure or by electrostatic forces that bond the soil to the fabric. One way to approach the problem of soiling is to prevent its deposition on the fabric. Another is to seek ways to facilitate its removal. Special finishes have been developed that have taken both of these approaches.