At the turn of the century, there were over 5,000 tanneries in the USA. Now there are under 100. While most of the basic steps and procedures remain true to earlier days, equipment, material handling, and specialty chemicals have greatly improved.
Historically, tanneries were divided into three basic areas: beamhouse, tanyard, and finishing. Beamhouse removes the meat, membrane and hair; tanyard “tans” or preserves the hide; and finishing adds dyes, oils, softeners, etc. While each modern leather tannery has its own secret recipe for the type of leather they produce, all have these three basic components.
Hides are received during deer season each year. Custom hides are individually marked and recorded with the owners name, address, etc. They are separated by color requested and salt packed to start the curing process.
Once, in the beamhouse, the hides are washed and run thru a fleshing machine. This machine uses a high speed roller knife to peel away all remaining meat and membrane. Next, the hair is removed using and unhairing solution and soaking process. This not only removes the hair, but the hair cup or root, leaving the smooth grain leather. To reduce the swelling in the hide from unhairing, it moves on to the bating and pickling. Here the hide is prepped for the tanyard.
Turner Fleshing Machine
In the tanyard, chromium salts are introduced to replace the biodegradable protein in the hide. By this process, the hide is preserved indefinitely. Almost all large commercial leather tanneries use this type of tanning. Once the hide completes this process, it is called “thru the blue”, and can be stored or sent on to finishing. A series of mechanical operations gets the hide ready for finishing. It is wrung to remove excess water using a Stehling Feed Thru hydraulic wringer; set out to soften, smooth, and loosen fibers in the hide with a Baker-Layton Setting Machine; and finally split for thickness to an even suitable glove and garment thickness on a Turner 57” Band Splitter.
The hides proceed directly to finishing, where they are dyed the desired shade and fatliquored with finishing oils to keep the leather soft and supple. Then off to the drying room for toggle drying, and a talc tumble milling to luster and finish the hides. At this point, custom hides are numbered to identify them with their owners, and a notify is sent out that the hide is ready. For those having articles made, it is on to the Glove Shop and the cutting department.
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