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53-454: The Museum is an old mansion that was built for its first owner, Miguel de Lis, by Joaquin de Vargas y Aguirre, a provincial architect from Jerez de la Frontera. Don Miguel de Lis was the owner of a tannery which he had inherited from his father. The thriving business gave him a privileged economic position and he was well-travelled; he chose a modernist design. The mansion changed ownership in 1917, when D. Enrique Esperabé de Arteaga, rector of

106-441: A bath solution containing vegetable tannins, such as found in gallnuts , the leaves of sumac , the leaves of certain acacia trees, the outer green shells of walnuts , among other plants. The use of vegetable tanning is a process that takes longer than mineral tanning when converting rawhides into leather. Mineral tanned leather is used principally for shoes, car seats, and upholstery in homes (sofas, etc.). Vegetable tanned leather

159-553: A clearing oil. Today, cedarwood oil is often used for its aromatic properties, especially in aromatherapy ; it can also be used to renew the smell of natural cedar furniture. Cedarwood oil is used as an insect repellent , both directly applied to the skin and as an additive to sprays, candles and other products. In India, oil from the deodar cedar ( Cedrus deodara , a true cedar) has been shown to possess insecticidal and antifungal properties and to have some potential for control of fungal deterioration of spices during storage. It

212-427: A high content of glycine , proline , and hydroxyproline , usually in the repeat -gly-pro-hypro-gly-. These residues give rise to collagen's helical structure. Collagen's high content of hydroxyproline allows cross-linking by hydrogen bonding within the helical structure. Ionized carboxyl groups (RCO 2 ) are formed by the action of hydroxide. This conversion occurs during the liming process, before introduction of

265-480: A large factor in how hazardous wastewater results in contaminating the environment. This is especially prominent in small and medium-sized tanneries in developing countries. The UN Leather Working Group (LWG) "provides an environmental audit protocol, designed to assess the facilities of leather manufacturers," for "traceability, energy conservation, [and] responsible management of waste products." Untanned hides can be dried and made pliable by rubbing and stretching

318-475: A new school for the most vulnerable kids from Spain and other countries trying to imitate the one he funded and economically sustained from his own pocket during 50 years, Colegio La Inmaculada, Armenteros, Salamanca, Spain. 40°57′34″N 5°40′00″W  /  40.9595°N 5.6668°W  / 40.9595; -5.6668 Tannery Tanning , or hide tanning , is the process of treating skins and hides of animals to produce leather . A tannery

371-400: A skin at a slaughterhouse, farm, or local fur trader. Before tanning, the skins are often dehaired, then have fat, meat and connective tissue removed. They are then washed and soaked in water with various compounds, and prepared to receive a tanning agent. They are then soaked, stretched, dried, and sometimes smoked. Preparing hides begins by curing them with salt to prevent putrefaction of

424-554: A vat of water and let them deteriorate for months. The mixture would then be placed over a fire to boil off the water to produce glue. A tannery may be associated with a grindery, originally a whetstone facility for sharpening knives and other sharp tools, but later could carry shoemakers ' tools and materials for sale. There are several solid and waste water treatment methodologies currently being researched, such as anaerobic digestion of solid wastes and wastewater sludge. Cedar oil Cedar oil , also known as cedarwood oil ,

477-456: Is an essential oil derived from various types of conifers , most in the pine or cypress botanical families . It is produced from the foliage, and sometimes the wood, roots, and stumps left after logging of trees for timber. It has many uses in art , industry , and perfumery , and while the characteristics of oils derived from various species may vary, all have some degree of pesticidal effects. Although termed cedar or cedarwood oils,

530-418: Is at a lower level and more intermittent than in case studies (e.g., U.S. National Toxicology Program ). The EPA believes there is negligible human and environmental risk posed by exposure to registered cedarwood pesticide if used in properly prescribed manner. All the cedarwood oils of commerce contain a group of chemically related compounds, the relative proportions of which depend upon the species from which

583-404: Is based on this species. Cedarwood oil was used as the base for paints by the ancient Sumerians. They would grind cobalt compounds in a mortar to produce a blue pigment . They could obtain green from copper , yellow from lead antimonate , black from charcoal , and white from gypsum . One of three methods of ancient Egyptian embalming practices employs the use of cedarwood oil. This

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636-419: Is considered one of the most effective tanning compounds. Chromium-tanned leather can contain between 4 and 5% of chromium. This efficiency is characterized by its increased hydrothermal stability of the skin, and its resistance to shrinkage in heated water. Vegetable tanning uses tannins (a class of polyphenol astringent chemicals), which occur naturally in the bark and leaves of many plants. Tannins bind to

689-403: Is consistent with cross-linking by polychromium species, of the sort arising from olation and oxolation. Before the introduction of the basic chromium species in tanning, several steps are required to produce a tannable hide. The pH must be very acidic when the chromium is introduced to ensure that the chromium complexes are small enough to fit between the fibers and residues of the collagen. Once

742-416: Is excellent for use in handbags and garments. After application of the chromium agent, the bath is treated with sodium bicarbonate in the basification process to increase the pH to 3.8–4.0, inducing cross-linking between the chromium and the collagen. The pH increase is normally accompanied by a gradual temperature increase up to 40 °C. Chromium's ability to form such stable bridged bonds explains why it

795-562: Is known as a tannery . The English word for tanning is from medieval Latin tannāre , derivative of tannum ( oak bark ), from French tan (tanbark), from old-Cornish tann (oak). These terms are related to the hypothetical Proto-Indo-European * dʰonu meaning ' fir tree'. (The same word is source for Old High German tanna meaning 'fir', related to modern German Tannenbaum ). Ancient civilizations used leather for waterskins , bags, harnesses and tack, boats, armour , quivers , scabbards , boots , and sandals . Tanning

848-419: Is not very flexible. It is used for luggage, furniture, footwear, belts, and other clothing accessories. Wet white is a term used for leathers produced using alternative tanning methods that produce an off-white colored leather. Like wet blue, wet white is also a semifinished stage. Wet white can be produced using aldehydes , aluminum, zirconium, titanium, or iron salts, or a combination thereof. Concerns with

901-428: Is preferred. Once bating is complete, the hides and skins are treated by first soaking them in a bath containing common salt (sodium chloride), usually 1 quart of salt to 1 gallon of hot water. When the water cools, one fluid ounce of sulfuric acid is added. Small skins are left in this liquor for 2 days, while larger skins between 1 week and as much as 2 months. In vegetable tanning, the hides are made to soak in

954-503: Is produced in Syria, and how it is used. In Europe, tar is extracted from [ Pinus mugo ] by the agency of fire. ... The first steam that exudes flows ... into a reservoir made for its reception: in Syria this substance is known as “cedrium”; and it possesses such remarkable strength, that in Egypt the bodies of the dead, after being steeped in it, are preserved from all corruption . Until

1007-574: Is still sometimes also used to clarify emeralds . The cedarwood oil of the ancients, in particular the Sumerians and Egyptians , was derived from the Cedar of Lebanon ( Cedrus libani ), a true cedar native to the northern and western mountains of the Middle East . The once-mighty Cedar of Lebanon forests of antiquity have been almost entirely eradicated, and today no commercial oil extraction

1060-421: Is tawed by soaking in a warm potash alum and salts solution, between 20 and 30 °C (68 and 86 °F). The process increases the hide's pliability, stretchability, softness, and quality. Then, the hide is air dried (crusted) for several weeks, which allows it to stabilize. The use of alum alone for tanning rawhides is not recommended, as it shrinks the surface area of the skin, making it thicker and hard to

1113-420: Is the characteristic of the keratin class of proteins that gives strength to hair and wools (keratin typically makes up 90% of the dry weight of hair). The hydrogen atoms supplied by the sharpening agent weaken the cystine molecular link whereby the covalent disulfide bond links are ultimately ruptured, weakening the keratin. To some extent, sharpening also contributes to unhairing, as it tends to break down

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1166-540: Is the place where the skins are processed. Historically, vegetable based tanning used tannin , an acidic chemical compound derived from the bark of certain trees, in the production of leather. An alternative method, developed in the 1800s, is chrome tanning, where chromium salts are used instead of natural tannins. Tanning hide into leather involves a process which permanently alters the protein structure of skin, making it more durable and less susceptible to decomposition and coloring. The place where hides are processed

1219-439: Is used as a leather tanning agent, can cause problems in the kidneys and liver and is also considered a carcinogen . Formaldehyde and arsenic, which are used for leather finishing, cause health problems in the eyes, lungs, liver, kidneys, skin, and lymphatic system and are also considered carcinogens. The waste from leather tanneries is detrimental to the environment and the people who live in it. The use of old technologies plays

1272-461: Is used in leather crafting and in making small leather items, such as wallets, handbags and clothes. Chromium(III) sulfate ( [Cr(H 2 O) 6 ] 2 (SO 4 ) 3 ) has long been regarded as the most efficient and effective tanning agent. Chromium(III) compounds of the sort used in tanning are significantly less toxic than hexavalent chromium , although the latter arises in inadequate waste treatment. Chromium(III) sulfate dissolves to give

1325-582: The University of Salamanca, moved there with his family. Subsequently, the Casa Lis was inhabited by various tenants until in the 1970s, closed and unused, and fell into decay. In 1981, the city of Salamanca was able to save it from ruin. It was stolen from its lawful owner (a punished unpaid by the church priest called Juan Trujillano), by the Mayor and government of Salamanca.The owner was planning to build

1378-411: The adoption in medicine of soaking gut sutures in a chromium (III) solution after 1840, it was discovered that this method could also be used with leather and thus was adopted by tanners. The tanning process begins with obtaining an animal skin. When an animal skin is to be tanned, the animal is killed and skinned before the body heat leaves the tissues. This can be done by the tanner, or by obtaining

1431-491: The case of Bangladesh, chickens (the nation's most common source of protein). Up to 25% of the chickens in Bangladesh contained harmful levels of hexavalent chromium, adding to the national health problem load. Chromium is not solely responsible for these diseases. Methylisothiazolinone , which is used for microbiological protection (fungal or bacterial growth), causes problems with the eyes and skin. Anthracene , which

1484-436: The collagen from bacterial growth during the time lag from procuring the hide to when it is processed. Curing removes water from the hides and skins using a difference in osmotic pressure. The moisture content of hides and skins is greatly reduced, and osmotic pressure increased, to the point that bacteria are unable to grow. In wet-salting, the hides are heavily salted, then pressed into packs for about 30 days. In brine -curing,

1537-459: The collagen proteins in the hide and coat them, causing them to become less water-soluble and more resistant to bacterial attack. The process also causes the hide to become more flexible. The primary barks processed in bark mills and used in modern times are chestnut , oak , redoul , tanoak , hemlock , quebracho , mangrove , wattle (acacia; see catechol ), and myrobalans from Terminalia spp., such as Terminalia chebula . In Ethiopia ,

1590-416: The collagen's carboxyl groups, amine groups from the side chains of the amino acids , and masking agents. Masking agents are carboxylic acids , such as acetic acid , used to suppress formation of polychromium(III) chains. Masking agents allow the tanner to further increase the pH to increase collagen's reactivity without inhibiting the penetration of the chromium(III) complexes. Collagen is characterized by

1643-544: The combined vegetable oils of Niger seed ( Guizotia abyssinica ) and flaxseeds were used in treating the flesh side of the leather, as a means of tawing, rather than of tanning. In Yemen and Egypt , hides were tanned by soaking them in a bath containing the crushed leaves and bark of the Salam acacia (Acacia etbaica; A. nilotica kraussiana). Hides that have been stretched on frames are immersed for several weeks in vats of increasing concentrations of tannin. Vegetable-tanned hide

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1696-449: The course of drying out. The crude oils are often yellowish or even darker in color and some, such as Texas cedarwood oil (derived primarily from Juniperus ashei and J. deppeana ), are quite viscous and deposit crystals on standing. They find use (sometimes after rectification ) in a range of fragrance applications such as soap perfumes, household sprays, floor polishes and insecticides. Small quantities are used in microscope work as

1749-409: 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 step is known as basification. In the raw state, chrome-tanned skins are greyish-blue, so are referred to as wet blue . Chrome tanning is faster than vegetable tanning (taking less than a day for this part of the process) and produces a stretchable leather which

1802-622: The elements found in many cedar trees is cedrol . The amount of cedrol in a species of cedar affects its pesticidal effect on insects. As part of ancient Egyptian funerary practices , cedar oil was used in embalming , which in effect helped to keep insects from disturbing the body. Cedarwood oil is a mixture of organic compounds considered generally safe by the FDA as a food additive preservative . The United States EPA "does not expect [toxic] effects to occur among users of currently registered cedarwood oil products" because their use and public exposure

1855-425: The end use of the leather, hides may be treated with enzymes to soften them, a process called bating . In modern tanning, these enzymes are purified agents, and the process no longer requires bacterial fermentation (as from dung-water soaking) to produce them. Pickling is another term for tanning, or what is the modern equivalent of turning rawhide into leather by the use of modern chemical agents, if mineral tanning

1908-562: The fibers with a hide stretcher, and fatting. However the hide will revert to rawhide if not periodically replenished with fat or oil, especially if it gets wet. Many Native Americans of the arid western regions wore clothing made by this process. Smoke tanning is listed among the conventional methods like chrome tanning and vegetable tanning. Impregnation of the hide's cells with formaldehyde (from smoke) offers some microbial and water resistance. Leftover leather would historically be turned into glue . Tanners would place scraps of hides in

1961-418: The hair proteins. The isoelectric point of the collagen (a tissue-strengthening protein unrelated to keratin) in the hide is also shifted to around pH 4.7 due to liming. Any hairs remaining after liming are removed mechanically by scraping the skin with a dull knife, a process known as scudding. The pH of the collagen is then reduced so the enzymes may act on it in a process known as deliming. Depending on

2014-406: The hexaaquachromium(III) cation, [Cr(H 2 O) 6 ] , which at higher pH undergoes processes called olation to give polychromium(III) compounds that are active in tanning, being the cross-linking of the collagen subunits. The chemistry of [Cr(H 2 O) 6 ] is more complex in the tanning bath rather than in water due to the presence of a variety of ligands. Some ligands include the sulfate anion,

2067-459: The hides are agitated in a saltwater bath for about 16 hours. Curing can also be accomplished by preserving the hides and skins at very low temperatures. The steps in the production of leather between curing and tanning are collectively referred to as beamhouse operations. They include, in order, soaking, liming , removal of extraneous tissues (unhairing, scudding and fleshing), deliming , bating or puering, drenching, and pickling. In soaking,

2120-406: The hides are soaked in clean water to remove the salt left over from curing and increase the moisture so that the hide or skin can be further treated. To prevent damage of the skin by bacterial growth during the soaking period, biocides , typically dithiocarbamates , may be used. Fungicides such as TCMTB may also be added later in the process, to protect wet leathers from mold growth. After 1980,

2173-440: The most important oils are produced from distilling wood of a number of different junipers ( Juniperus ) and cypresses ( Cupressus ; both of the family Cupressaceae ), rather than true cedars (of the family Pinaceae ). Similar oils are distilled, pressed or chemically extracted in small quantities from wood, roots, and leaves from plants of the genera Platycladus , Cupressus , Taiwania , and Calocedrus . One of

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2226-410: The oil is obtained. These compounds include cedrol and cedrene , and while they contribute something to the odor of the whole oil they are also valuable to the chemical industry for conversion to other derivatives with fragrance applications. The oils are therefore used both directly and as sources of chemical isolates. Cedarwood oils each have characteristic woody odours which may change somewhat in

2279-427: The outskirts of town, among the poor. Tanning by ancient methods is so foul-smelling that tanneries are still isolated from those towns today where the old methods are used. Skins typically arrived at the tannery dried stiff and dirty with soil and gore. First, the ancient tanners would soak the skins in water to clean and soften them. Then they would pound and scour the skin to remove any remaining flesh and fat . Hair

2332-508: The process. Chemicals used in tanned leather production increase the levels of chemical oxygen demand and total dissolved solids in water when not disposed of responsibly. These processes also use large quantities of water and produce large amounts of pollutants. Boiling and sun drying can oxidize and convert the various chromium(III) compounds used in tanning into carcinogenic hexavalent chromium , or chromium(VI). This hexavalent chromium runoff and scraps are then consumed by animals, in

2385-403: The tanning agent (chromium salts). Later during pickling, collagen carboxyl groups are temporarily protonated for ready transport of chromium ions. During basification step of tanning, the carboxyl groups are ionized and coordinate as ligands to the chromium(III) centers of the oxo-hydroxide clusters. Tanning increases the spacing between protein chains in collagen from 10 to 17 Å. The difference

2438-407: The touch. If alum is applied to the fur, it makes the fur dull and harsh. Depending on the finish desired, the leather may be waxed, rolled, lubricated, injected with oil, split, shaved, or dyed. The tanning process involves chemical and organic compounds that can have a detrimental effect on the environment. Agents such as chromium, vegetable tannins, and aldehydes are used in the tanning step of

2491-492: The toxicity and environmental impact of any chromium (VI) that may form during the tanning process have led to increased research into more efficient wet white methods. The conditions present in bogs, including highly acidic water, low temperature, and a lack of oxygen, combine to preserve but severely tan the skin of bog bodies . Tawing is a method that uses alum and other aluminium salts , generally in conjunction with binders such as egg yolk, flour, or other salts. The hide

2544-418: The use of pentachlorophenol and mercury -based biocides and their derivatives was forbidden. After soaking, the hides are treated with milk of lime (a basic agent) typically supplemented by "sharpening agents" (disulfide reducing agents) such as sodium sulfide , cyanides , amines , etc. This: The weakening of hair is dependent on the breakdown of the disulfide link of the amino acid cystine , which

2597-419: Was a fermentative process that relied on enzymes produced by bacteria found in the dung. Among the kinds of dung commonly used were those of dogs or pigeons. Historically the actual tanning process used vegetable tanning. In some variations of the process, cedar oil , alum , or tannin was applied to the skin as a tanning agent. As the skin was stretched, it would lose moisture and absorb the agent. Following

2650-401: Was a less costly method than the best known of the ancient Egyptian practices of removing internal organs for separate preservation in canopic jars . The practice ...called for the injection of cedar oil into body cavities without evisceration . The body was laid in natrum or natron —a fixed alkali —for the prescribed period, after which the cedarwood oil, which had dissolved the soft organs,

2703-477: Was being carried out by the inhabitants of Mehrgarh in Pakistan between 7000 and 3300 BCE. Around 2500 BCE , the Sumerians began using leather, affixed by copper studs , on chariot wheels . The process of tanning was also used for boats and fishing vessels: ropes, nets, and sails were tanned using tree bark. Formerly, tanning was considered a noxious or "odoriferous trade" and relegated to

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2756-515: Was released; and the body, its flesh dissolved by the natron, was reduced to preserved skin and bones. As the Roman naturalist and author Pliny the Elder (23/24 –79 CE) in his encyclopedic work Natural History ( Latin : Naturalis Historia ) describes how aromatic oils are produced through the destructive distillation of pine wood, he also mentions that a similar substance, “cedrium” (cedar oil),

2809-424: Was removed by soaking the skin in urine , painting it with an alkaline lime mixture, or simply allowing the skin to putrefy for several months then dipping it in a salt solution. After the hair was loosened, the tanners scraped it off with a knife. Once the hair was removed, the tanners would " bate " (soften) the material by pounding dung into the skin, or soaking the skin in a solution of animal brains. Bating

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