We manufacture the finest calf leather for demanding clients. The well-known Freudenberg – Box Calf is produced according to traditional tanning methods. Focus on craft and care for the environment are our main objectives. KEGAR Sp. z o.o. tannery is a complete service company and manufactures leather by order and exclusively for the Weinheimer Leder GmbH.
During the fleshing process the extraneous tissue (flesh and fat residues) is stripped from the surface of the hide by means of a fleshing machine. This machine is equipped with a rotating blade cylinder, with spiral blades arranged in a V-shape. The blades have to be extremely sharp to remove completely the subcutaneous connective tissue. In the past, the hides were scraped off manually with a traditional fleshing knife on a radial fleshing beam. This required great skills and craftmanship, in order not to damage the hide.
The traditional painting is not a common practice anymore. The main purpose of this process is the dehairing of the hide. The flesh side is treated with a chemical dissolution in order to remove the hair and to prepare its structure for further production steps. After a certain diffusion time the hair roots start to dissolve. The following liming operation opens the fibre structure of the hide. The painting procedure can also take place in drums, where the chemicals are added into a relatively low float. Subsequently the water amount is raised to initiate the liming process.
In the process of deliming the ultimate goal is to eliminate the lime swell. During bating the hides are further deswelled with enzymatic applications, to make them pliable for pickling and the subsequent tanning process. Pickling describes the process of treating with acids, to set the defined pH value and the addition of salts, to prevent the undesirable acid swelling. During the tanning a check is made by cutting the cross section of the hide to observe the degree of penetration of the tanning liquor. At this point HIDE becomes LEATHER. Chrome and vegetable-synthetic tanning are still the most commonly used tanning methods, together with the recently developed olive tanning, based on olive tree leaves extract.
During sammying most of the capillary water from the leather is absorbed. Nowadays the tanneries work on through feed sammying machines. The wet leather is conveyed on felts through the pressure rollers. Such machines can also be equipped with an extra setting-out cylinder to smooth out the wrinkles. Afterwards the leather is closely inspected in terms of the selection and measured for area and thickness.
A shaving machine allows to achieve an even thickness of the leather. The working principle is similar to the fleshing machine, a rotating blade cylinder, with spiral blades arranged in a V-shape removes the irregularities remained on the flesh side. The grinding device works almost constantly to keep the cutting edge of the blades extremely sharp. Pressure and feed rollers enable an uniform pressure and feed rate. The feed speed is adjustable and depends on the type of the processed leather.
At first the acid coming from the tanning process is neutralized. Filling agents and dyestuffs follow according to the leather type. Today almost every shade of a colour can be created to meet the current fashions trends. The application of fats helps to separate the fibres and is determined by the leather type and its intended purpose. At the same time suitable synthetic retanning and filling agents can change or adjust the essential properties and final appearance of the product. All mentioned operations take place mainly in drums and end with an acid fixation.
The are several techniques to dry the leather, involving vacuum drying (the moisture is sucked out) and hang drying (the leather goes through a drying tunnel). The current drying procedure is often a combination of vacuum drying followed by hang drying in tunnels. Another option is a toggling machine, where the leather is stretched on a perforated metal frame by means of toggle clips and placed in a preheated drying tunnel.
Staking increases the softness of the leather after drying. It can be a mechanical or manual operation. In a through feed staking machine the leather is placed between textile conveyor belts with vibrating plates. The action of the beating jaws kneads and stretches small areas of leather resulting in the softening of its fibres. The so-called “arm” staking machines are not so common anymore and are used only to work with special types of leather. The staking-arm pulls the leather and flexes it over staking blades.
The process of milling uses drums with required rotation speed. The rotating force makes the leather fall from the highest point of a drum on pins and paddles inside which transport it back up. As a result of constant pulling, stretching and compressing the leather becomes softer and the natural grain effect more visible.
Here the suitable surface coating operations are employed to create the final appearance of the leather. The application of primes, pigment mixtures and mechanical processing such as embossing and ironing give the leather a gloss or matte, a one- or multicoloured, a smooth or grained finish, depending on the current fashion trends. The pigment mixtures are prepared in the “colour kitchen”. In a manual spray booth the first check of the colour combinations is carried out.
Especially by the current fashion leather as well as by classical articles the slightly defected grain is enhanced. The leather can embossed with a versatile range of designs. Smooth chromed plates (“mirror plates”) apply shine on the grain. All the above mentioned operations take place under defined temperature and pressure parameters.
By hand boarding the leather is folded over the grain side. By means of a boarding hand tool it is compressed and rolled at the same time. This action produces a fine, uniform design of wrinkles. Folding in 4 quarters results in a rectangular grain pattern and boarding over 8, 16 or more quarters with an elegant “Saffiano” grain. For this operation the leather has to be very firm and elastic at the same time. Today the boarded grain effect is mainly a result of embossing with boarded leather design.