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Industry Affiliations

United States Hide, Skin & Leather Association
Leather Industries of America
International Council of Hides, Skins & Leather Traders Association
International Council of Tanners
United States Department of Agriculture
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There are several methods of curing hides, ranging from the conventional method of pack curing to agitated brine in a raceway, with several variations. There is also the Hide Processor ("concrete mixer") method of curing.

Simply stated, hide curing is a process in which hides are treated with common salt to arrest bacterial and enzymatic decomposition to which they are subject within a few hours of the death of the animals.

Theoretically, all hides are brine cured. Crystalline sodium chloride, or common salt, cannot be absorbed by the hide. Only after the salt crystals have been dissolved in water to make a brine can the curing proceed.

In the case of the conventional method (pack curing), the salt crystals draw moisture from the hide which dissolves the salt. The pack is built with the intention of retaining this pickle or brine, thus completing the cure.

As the salt draws the moisture from the hides, the moisture content is reduced sufficiently to produce an environment unfavorable for bacterial growth. The near saturation of the remaining moisture with sodium chloride also has a bacteriostatic effect and these two factors, along with a reduced temperature in the curing cellar, combine to produce satisfactory cured hides.

In the brine curing process, the hides are in contact with saturated brine at all times. This serves to reduce the time required to cure hides from 30 days in the case of pack curing to 24 hours or thereabouts by brine curing.

Brine curing in the hide trade generally refers to one of three methods of curing (1) raceway cure; (2) curing by means of a Hide Processor, or (3) vat cure. However, as mentioned above, there are variations.

(Source: Hides & Skins. National Hide Association. Page 47)

Since the beginning of 1963, UHC has used the raceway cure method in Modesto, California. Prior to that time at their Oakland, California plant, the wetsalt pack method was used. The method of brine curing by raceway is as follows:

The most common type of brine curing employs an oval vat with an oval island in the center, making what has been aptly described as a "raceway vat". Two paddles at opposite sides cause the hides to move slowly around and around. The paddles usually have 6 blades, which dip 10 to 16 inches in the brine, and revolve at a rate of 12 to 16 revolutions per minute. The raceways are usually 8 feet wide and 5 feet deep. This system requires a minimum of 4 pounds of saturated brine for each pound of green uncured hide. A popular size for these tanks is 15,000 gallons. A tank of this size has a capacity of about 550 hides. Some tanks being used in the industry will accommodate over 800 unfleshed hides, or 1200 fleshed hides. The usual installation will consist of three tanks, two of which will hold a full day's production. The third tank is used for loading the following morning while the cured hides are being removed from the first tank loaded the day before. Thus the tanks are used in a constantly rotating arrangement.

As is the case with pack cured hides, moisture is drawn from the green hides in the brine tank. To prevent dilution, a portion of the brine is usually circulated through a salt dissolving chamber, commonly known as a lixator. This serves the double purpose of keeping the brine close to saturation, and filtering out some of the dirt and other solids suspended in the brine. As a rule, the brine is passed through a rotary screen to remove hair and fat prior to going to the lixator. However, in some installations fine salt is slowly added to the curing tanks along with the hides and the turbulence set up by the paddles is relied on to keep the brine up to strength.

In the early brine curing installations of the United States, green hides were trimmed of snouts, lips, ears, and tails and placed in the brine. After an overnight cure, they were removed and placed in an ordinary pack, without salting, for 15 days to drain. The first innovation in brine curing procedure came with the development of a heavy duty whole hide combination fleshing and demanuring machine specifically designed for packinghouse use. This machine accomplished the simultaneous removal of manure from the hair side and fat and flesh from the flesh side of green hides. This permitted a faster and better cure, and better hide grading since scores, brands, etc. were more clearly visible. The biggest advantage to the tanner was the saving in freight on the materials removed which have little or no value in making leather.

The next improvement was the development of the hide washing machine. This device consisted of a rotary screen through which the hides were tumbled under jets of chilled water. This served to remove much of the manure and blood from the hides and also caused the fat to harden, resulting in an improved fleshing operation.

In addition to improvements in the pre-cure operations, there have also been changes in the method of draining the hides. Instead of placing hides in packs to remove excess brine, some operators are hanging the hides over horses to drain for 24 or 48 hours and then bundling them. The bundled hides are then stored in the various grades until enough hides to make a carload have been accumulated. A recent improvement has been the development of a machine for mechanically wringing fleshed hides as they are removed from the brine curing tank. These hides are sufficiently dry to be bundled immediately. Using this machine, the cured hides are bundled and ready for shipment the day after slaughter of the animal.

A variation from the above wash-flesh-brine cure procedure is one in which green hides are first brine cured and then fleshed. This has the advantage of eliminating the washing operation and requiring only one fleshing machine. Since the cured hides are no longer perishable, immediate fleshing is not necessary and the single fleshing machine can be operated for two or even three shifts.

The reason for the popularity of raceway brine curing among the larger packers and hide dealers is that this procedure lends itself to automation, thus reducing labor requirements. In modern systems, the hides are moved by conveyors to the washers, then to the fleshing machine and finally into and out of the brine tanks.

(Source: Hides & Skins. National Hide Association. Pages 73-75)

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2125 Oak Grove Rd., STE 121 - Walnut Creek, CA 94598
Phone: (925) 935-9550