Decatising or decatizing, also known as crabbing, blowing, and decating, is the process of making permanent a textile finish on a

cloth Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, and different types of fabric. At first, the word "textiles" only referred to woven fabrics. However, weaving is n ...

, so that it does not shrink during garment making. The word comes from the French décatir, which means to remove the cati or finish of the wool. Though used mainly for

wool Wool is the textile fiber obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have some properties similar to animal w ...

, the term is also applied to processes performed on fabrics of other fibers, such as

cotton Cotton (), first recorded in ancient India, is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure ...

linen Linen () is a textile made from the fibers of the flax plant. Linen is very strong and absorbent, and it dries faster than cotton. Because of these properties, linen is comfortable to wear in hot weather and is valued for use in garments. Lin ...

polyester Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some natura ...

. Crabbing and blowing are minor variations on the general process for wool, which is to roll the cloth onto a roller and blow steam through it. Decatized wool fabric is interleaved with a cotton, polyester/cotton or polyester fabric and rolled up onto a perforated decatizing drum under controlled tension. The fabric is steamed for up to ten minutes and then cooled down by drawing ambient air through the fabric roll. The piece is then reversed and steamed again in order to ensure that an even treatment is achieved. There are several quite different types of wool decatizing machines including batch decatizing machines, continuous decatizing machines, wet decatising machines and dry decatizing machines. For example: In the 1920s, James Bailey textile engineers (Slaithwaite, Yorkshire) developed a successful and efficient means of decatising by essentially putting two blowing machines back to back. These were used by most if not every woollen & worsted finishers in the UK, and became the mainstay of Batch Decaters throughout the mid 20th century. In the early 1950s, They re-patented the Bailey 'Empire blowing, steaming or decatising machine' advertising a new design, better finish, increased output, and less steam consumption. This design sold very well, as they were simply the best built and most effective machines in the world at the time. In the UK, these machines are still used to this day at worsted cloth finishers as Crabbing machines. Crabbing (sometimes called greasy blowing) is a type of special decatising done mostly to worsted fabrics in the 'grey state', or when they come off the weaving loom. It is the first step in the traditional finishing process of fine worsted cloths in the UK, after the cloth is weighed. The objective of crabbing is to achieve a 'preliminary set' on the cloth before it is scoured/washed in soap. This stabilises the cloth in place during the washing and milling process and can prevent warping of the cloth and distortions occurring.

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