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Objective evaluation of opacity of clothing and technical textiles
Textiles are meant to maintain decency in many areas of life. On the other hand a certain level of transparency is actually wanted for materials used for clothing, curtains, scaffold sheeting or exhibition stand elements. The scientists at the Hohenstein institutes offer support to clothing manufacturers, builders, architects and exhibition stand constructors for the selection of textiles which meet the individual requirements for opacity or transparency.
They have developed an objective measuring method for classifying the opacity or transparency of textiles. The new test methods can be used for technical textiles as well as for textiles for the clothing industry. Determining opacity allows manufacturers targeted optimisation of their products and minimisation of complaints. A corresponding label on the product also provides them with the option to make it easier for their customers to select suitable products for different areas of use.
White or coloured clothing textiles such as blouses, T-shirts and work clothing are tested while dry, bathing textiles while wet and dry, and then classified as “opaque” (“pass”) or “transparent” (“fail”). The measurements take into account two different skin types and three contrasting colours to simulate undergarments. The result is determined on the basis of the so-called “worst case”. For clothing this is e.g. white underwear and a dark skin type.
The labels “opaque” or “not opaque” are not sufficient for technical textiles for exhibition stand construction, textile advertising objects, decorative fabrics, curtain fabrics etc. because a certain transparency is often required from these textiles. Therefore a separate evaluation scale was developed for this group of textiles, describing the level of transparency in 5 stages. This scale extends from very transparent, transparent and slightly transparent to nearly opaque and completely opaque.