We use a Stork rotary screen printer to apply the flame retardant paste as a coating to the reverse side of the fabric. The screens used have etched patterns of holes within their structure through which the coating paste is squeezed onto the fabric. The coating machine can be adjusted to deliver a broken or continues coating dependent on the fabric requirements. Once applied, the coating is dried and cured in an gas fired dryer. The curing process ensures the flame retardant within the coating is not lost should the fabric come in contact with water whilst in use. This aspect is important for subsequent ignitability testing which almost always requires a cleansing (30 minute water soak) procedure to be conducted prior to testing.
The backcoating operation is usually restricted to fabric for upholstery. The characteristics of the flame retardant system used in upholstery backcoating is optimised for use with a cover and filling material (see “Fire Propagation” section for more details). It may be possible to treat curtain material using this procedure but the coating often detracts from the fabric drape.
We use a variety of padding techniques to apply water based flame retardant chemicals to fabrics. These chemicals are impregnated into the textile fibres rather than forming a coating (as in backcoating) on the reverse side of the fabric. This results in better fabric drape compared with backcoating. Fabrics so treated should only be dry cleaned when in use due to the water soluble nature of the chemicals.
A variety of chemical formulations are available. The one used depends on the fibre composition. The padding technique used depends on the the fabric construction and any finishes which may have been applied to the material during manufacture. After applying the chemical, the fabric is dried in a gas fired dryer.
Padding is used to apply fluorocarbon finishes to fabric as well as flame retardants. Fluorocarbon finishes impart water/oil repellent properties to the fabric. These finishes do not make the fabric “water proof” but instead reduce the risk of fabric staining following fluid spillage onto the textile surface.