Modern Methods Of Tanning In America
The first stage is the preparation for tanning. The second stage is the actual tanning and other chemical treatment. The third stage, known as retanning, applies retanning agents and dyes to the material to provide the physical strength and properties desired depending on the end product. The fourth and final stage, known as finishing, is used to apply finishing material to the surface or finish the surface without the application of any chemicals if so desired.
Preparing hides begins by curing them with salt. Curing is employed to prevent putrifaction of the protein substance (collagen) from bacterial infection during the time lag that might occur from procuring the hide to when it is processed. Curing removes excess water from the hides and skins using a difference in osmotic pressure. The moisture content of hides and skins get greatly reduced. In wet-salting, the hides are heavily salted, then pressed into packs for about 30 days. In brine-curing the hides are agitated in a salt water bath for about 16 hours. Generally speaking, methods employed for curing greatly make the chance of bacterial growth unfavorable. Curing can also be done by preserving the hides and skins at a very low temperature.
The hides are then soaked in clean water to remove the salt and mainly to bring back the moisture content to a desirable level so that the hide or skin can be treated with chemicals in an aqueous medium. This process is known as "soaking" and sometimes a hydrating agent is also employed along with water in a very low percentage for hides and skins which have become very dry.
Liming process of hides and skins
After soaking, the soaked hides and skins are taken for the next operation where these are treated with milk of lime with or without the addition of sharpening agents like sulfide, cyanides, amines etc. The objective of this operation are mainly to:
Remove the hairs, nails and other keratinous matters
Remove some of the interfibrillary soluble proteins like mucins
Swell up and split up the fibers to the desired extent
Remove the natural grease and fats to some extent
Bring the collagen to a proper condition for satisfactory tannage
The weakening of hair is dependent on the breakdown of the disulfide link of the amino acid called cystine, which is the characteristic of the keratin class of protein like hair and wools. The hydrogen atoms supplied by the sharpening agent reduce the cystine molecule to cystine and the covalent links are ruptured.
The isoelectric point of the collagen is also shifted to around 4.7, due to liming which is more towards an acidic tannage. Unhairing agents used during liming are: sodium sulfide, sodium hydroxide, sodium dithionite, Arsenic sulfide, calcium hydrosulfide
The majority of hair is then removed using a machine, with remaining hair being removed by hand using a dull knife, a process known as scudding. Depending on the end use of the leather, hides may be treated with enzymes to soften them in a process called "bating." But before bating, the pH of the collagen is brought down to a lower level so that enzymes might act on it. This process is known as "deliming." Once bating is complete, the hides and skins are treated with a mixture of common salt and Sulphuric acid in case a mineral tanning is to be done. This is done to bring down the pH of collagen to a very low level so as to facilitate the penetration of mineral tanning agent into the substance.
This process is known as "Pickling." The common salt penetrates the substance twice as fast as the acid and checks the ill effect of sudden drop of pH.
Tanning can be performed with either vegetable or mineral methods. Before tanning, the skins are unhaired, degreased, desalted and soaked in water over a period of 6 hours to 2 days. To prevent damage of the skin by bacterial growth during the soaking period, biocides, such as pentachlorophenol, are used.
Two men pressing the leather near the end of the tanning process in an American tannery.
Vegetable tanning uses tannin (this is where the name tanning comes from). Tannin occurs naturally in bark. The primary barks used in modern times are chestnut, oak, tanoak, hemlock, quebracho, mangrove, wattle and myrobalan. Hides are stretched on frames and immersed for several weeks in vats of increasing concentrations of tannin. Vegetable tanned hide is flexible and is used for luggage and furniture.
Mineral tanning usually uses chromium in the form of basic chromium sulfate. It is employed after picking. Once the desired level of penetration of chrome into the substance is achieved,the pH of the material is raised again to facilitate the process. This is known as "basification". In the raw state chrome tanned skins are blue and therefore referred to as "wet blue."
Chrome tanning is faster than vegetable tanning (less than a day for this part of the process) and produces a stretchable leather which is excellent for use in handbags and garments. (Encarta, 2003) Depending on the finish desired, the hide may be waxed, rolled, lubricated, injected with oil, split, shaved and, of course, dyed. Suedes, nubucks etc. are finished by raising the nap of the leather by rolling with a rough surface.
Modern Day American Tanner Dying
This Is The Facts And The Photos Tell The Untold Story Behind Gloss And Glimmer Of Foreign Made Leather Products In American Showrooms Everywere.
Its Always your Choice - Buy American And Insure Your Economic Future
Understanding True Quality Makes All The Difference
When you purchase investment quality furnishings, doors, gates, cabinets, lighting and hardware they will appreciate and keep up with inflation or exceed most other investments. For this reason, becoming wealthy has very little to do with a higher education or having a lot of extra money. It is truly making wise decisions and a state of mind that allows for you to pay once for a good value and continue to grow wealth while enjoying living in your investment. Not to mention this type of investing has many other benefits, such as priceless family heirlooms that have meaning and the ability to pass on your legacy to future generations.
Over Ninety Five Percent Of Furnishings Offered In America Today,
" No Matter The Brand Name"
Are Foreign Made For Profit Only
The "Brand Name" Rip Off Of The American Consumer
Why Would Any One Pay 300% - 800% Mark Up For A Cheap Inferior Third World Made Furnishing? - When You Can Purchase Top American Made Quality For Less
It's A Simple Fact
When You Purchase A Third World Product You Are Working Against The American Economy.
You are thus working against yourself and your future employment or the employment of the customers your business depends upon. In addition, your choice works against employing American workers making quality American products as well as allowing these old brand name American profiteers to take advantage of the American consumer using these slight of hand tactics.
This Is Not Sour Grapes - And We Challenge Any Expert To Demonstrate Different
It is the facts of the furniture and door industry as a whole for past eight to ten years as we are living it. Simply turn on any news channel and see the results in action.
In Nine Decades Scottsdale Art Factory Has Never Changed Its Policy of "Made In America By American Workers Using American Made Materials".
We Will Never Sell Our Corporate Soul," Family Name" For A Fast Buck, And We Make No Apologies For Being Proud Flag Waving American Manufacturers.
Conclusion: If your client is in the market for the best quality hand made in America solid wood doors or furniture or hand forged ornamental iron cabinet knobs, entrance door handles, entrance gates, iron fencing, iron furniture, hand forged lighting etc. commercial or residential
Scottsdale Art Factory Is The Right Choice.
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"When Everything Made In America Was Built To Last Forever"
And Craftsmen Were Proud To Sign Their Work
Handmade Sofas & Chairs
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Custom Furniture Makers - Scottsdale Art Factory
Scottsdale Art Factory, a custom furniture, door, gate, and handmade furnishing manufacturer based in Scottsdale, Arizona, and Designs by H.J. Nick, have been designing and building some of the world's finest furnishings all hand crafted in America since 1913. Most of our clients want a furnishing that has a big WOW factor and timeless elegance. They all want investment value furnishings that makes a proper statement reflecting their personality, or the personality of the environment for which the designer custom furnishings are intended.
Designer Leather Furniture
We only use the best Full Grain Leather available from American tanneries. Full-grain leather or top-grain refers to the upper section of a hide that previously contained the epidermis and hair. The hair and the epidermis have been removed from the hide/skin. Full-grain refers to hides that have not been sanded, buffed or snuffed (otherwise known as Corrected) in order to remove imperfections (or natural marks) on the surface of the hide, although is never perfect. The grain remains in its natural state which will allow the best fiber strength, resulting in greater durability.
The natural grain also has natural breathability, resulting in greater comfort for clothing. Rather than wearing out, it will develop a natural patina and change in its appearance over time with some cracking and splitting. The finest leather furniture and footwear are made from full-grain leather. For these reasons only the best hides are used in order to create full-grain or top-grain leather. Fine art high end fabric is available for all custom furniture. Order your designer furniture hand made custom for you at Scottsdale Art Factory - call 1-800-292-0008.
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