Leather grease
Leather fat is in part because the leather contained natural fat and also a product for maintenance of leather products. Fats have also been used in what is known as fat tanning for thousands of years .
properties
The natural fat content of skin is normally around 1%, in sheepskin it is around 12%. The water content should be significantly higher. Adding leather fat changes material properties such as elasticity , tear resistance and water absorption capacity depending on the type of leather. By coating the collagen fibers in the leather with the leather fat, the decomposition of the leather through oxidation and hydrolysis is reduced. With some types of leather an occasional refatting is necessary.
Too high a content of biological fats in the leather can lead to permanent damage, in the long term to what is known as fat consumption . Leather fat formulations therefore usually consist of leather care substances that are as inert as possible . Since maximum penetration of the leather fat and high suppleness of the leather are desired, long-chain paraffins are usually used as base materials , occasionally with other additives such as UV- absorbing substances such as propyl gallate , O-phenylenediamine or tocopherol to protect against solar radiation and as protection against oxidation .
Since the 1990s, beeswax and carnauba wax have been increasingly added at the customer's request , but lead to a stronger stick-slip effect and, as a result, to a stronger "creaking" effect . Leather grease formulations are less viscous than shoe polish and have a greater depth effect on the treated leather, while the more solid waxy products such as shoe polish have a stronger surface effect. Leather grease is only conditionally suitable for chrome-tanned leather.
history
In the past, leather grease was often used for the care of leather because the types of leather suitable for it (vegetable-tanned hard- wearing leather for footwear , belts , carrying means , slings , drive belts , riding saddles or harness , also book covers ) were more common. Due to the widespread use of chrome upper leathers (80% of all leather produced worldwide) and the progress made in the manufacture of alternative impregnating agents, the importance of leather fats has decreased significantly.
The recipes that have been tried and tested over decades (mixtures of oils and fats of animal, vegetable and, from the 1930s, synthetic origin) are rarely modified by the manufacturers, and if so, only in insignificant details.
Impregnation with fat
The impregnation with water-repellent materials based on paraffins (most proofing sprays ) is a so-called closed impregnation , the breathability impaired and the steam storage capacity of the leather. For impregnation purposes, leather grease is mainly used for shoes. That is why liquid impregnating agents, often also in the form of propellant gas sprays ( aerosols ), based on silicone oils ( silicone spray ) or fluorocarbons ( Teflon spray ) are used today. These offer an open impregnation without pore closure and, in the case of fluorocarbons, are more insensitive to contamination, but have as yet unknown emission values .
Upholstered furniture made of leather can be treated with leather grease, but excess leather grease should be cleaned very thoroughly to avoid staining textiles. For shoe care, it is not suitable for producing a contact-stable gloss due to its lower polishability . Leather fat is used in very small quantities for heavily stressed (leached) vegetable-tanned upper leathers, such as those found in work boots and work shoes by farmers and construction workers or in mountain boots .
Fat tanning
The fat tanning, also known as chamois tanning, is used in particular for chamois, deer, roe deer and reindeer, especially sheepskins , and occasionally also goat skins and beef split . Tanning agents are trane ( esters of highly saturated fatty acids from fish and marine mammals) and rapeseed oil , but also sulfated fat products. Typical end products of chamois tanning are, for example, traditional trousers and riding breeches. Only with Tran tanned leather are as old chamois referred. New hemisphere leather is pre-treated with formaldehyde and tanned with oil. It contains more bound fat and has higher shrinkage temperatures.
Leather grease in the fur trim
As of fur or dressing that is tanning called of fur in which the hair is left on the leather tanning or trimming process. As with leather tanning, part of the natural fat is removed from the hide during dressing. In order to keep it soft and supple, it has to be added again afterwards. As one option, this can be done by spreading natural or chemically derived fats. Then the skins are tumbled or, in the case of finer types of skin, kneaded in order to work the fat deep between the tufts of fibers of the leather. After a slight drying, they are expelled, that is, stretched, to remove excess fat. The hair is then cleaned with wood flour in the lauter tun (→ see fur cleaning ). Greasing with emulsified fats and related substances (Lickerfette) in the barrel at medium temperatures is called Lickern .
As a furrier butter various technical fats were known, which are used for fulling the skins, as furriers milk by the furriers, particularly in the transformation of pelts , used for greasing fat emulsion .
Individual evidence
- ^ Anne Sudrow: The Shoe in National Socialism: A Product History in the German-British-American Comparison , Wallstein Verlag, p. 92 f. On-line
- ↑ H. Schulz: High-quality, natural upholstery leather with high fastness properties and low emissions , Research Institute for Leather and Plastic Sheets (FILK). Retrieved March 12, 2013.
- ^ A b K. Günter Rordorf: Small leather and fur customer. Leather and fur cleaning. 2nd edition, Bussesche Verlagshandlung, Herford 1966, p. 23
- ↑ Erika Rowald: The German tobacco product finishing a wage industry . Verlag Der Rauchwarenmarkt , Leipzig, inaugural dissertation undated (approx. 1931), p. 59
- ↑ Kurt Nestler: The smoking goods refinement . Deutscher Verlag GmbH, Leipzig 1925, p. 35