The German company Konrad Hornschuch have marketed coated textiles under the umbrella brand Skai® for over 50 years. Like other brand names before it, such as Post-It Notes, Bubble Wrap, Velcro and Tupperware, Skai has become the generic name for high quality coated fabrics.
Coated fabrics are synthetic materials made from a textile base layer with a plastic coating (usually a polyurethane or vinyl). Coated textiles have been used for many years as substitute for leather. Leather substitutes go by many names - skai, PU, imitation leather, faux leather, pleather, leatherette vegan leather, eco leather, synthetic leather, future fabric – but they are all actually coated fabrics.
Historically, vinyl-coated fabrics were considered the most suitable substitute for leather. The original polyvinyl chloride (PVC) fabrics consisted of a closely woven fabric base with a non-expanded vinyl laminate applied to the surface. In its natural state, vinyl is quite stiff. Plasticisers needed to be added to make the vinyl more flexible, even so, these fabrics were still stiff, lacked the handle of leather, and were difficult to upholster. They also tend to harden and crack quickly due to the migration of the plasticiser.
In the 1950s, expanded vinyl-coated fabrics were developed, which had handle and drape properties similar to those of leather. These fabrics have a knitted fabric as the base material, and intermediate layer of cellular PVC (a foamed or expanded form of vinyl), and a wear-resistant top coat (usually consisting of a vinyl skin coat with clear acrylic finish).
Polyurethane (PU) is also commonly used as a fabric coating. Polyurethane-coated fabrics have a similar constriction to vinyl-coated fabric: they have a knitted base fabric, a polyurethane foam middle layer, and a wear resistant topcoat. Plasticisers are not required to make polyurethane coatings soft and flexible.
Both expanded vinyl and polyurethane-based imitation leather are widely used for furniture upholstery, bags, shoes, and auto upholstery. PVC coated fabrics are lower in cost, however PU coated fabrics are considered superior for the production of imitation leather. PVC coated fabrics have a cool feel, and tend to crack as they age due to plasticiser migration. PU coated fabrics have a feel and drape is closer to that of leather, are more durable, are more flexible, and, because no plasticisers are used in PU coatings, they do not usually crack with age. PU coated fabrics also have higher water vapour permeability compared PVC coated fabrics, so they are more breathable.
In the 1960s DuPont introduced the first polomeric imitation leather. Poromerics are second-generation imitation leathers. Like other imitation leathers, poromerics are synthetic leather substitutes made from a plastic coating on a fibrous base layer. However, the plastic layer is treated in such a way that that it has a microporous structure and the materials used as backing are generally a non-woven fabric that may or may not be reinforced with a knitted or woven fabric. As a result, poromeric imitation leather has better air and water vapour permeability (breathability) that other imitation leathers, and looks and feels more like genuine leather. Poromeric fabrics are usually coated with polyurethane, however vinyl coated poromerics are also available (also called breathable vinyl, micro-pourous vinyl or absorptive vinyl). With the exception of non-expanded vinyl-coated fabrics ("old fashioned vinyl"), all types of coated fabrics are still widely used in the furniture industry.