The concentration of chemicals used in the production of leather and its effects on humans with acute chrome allergies is well documented. Often these reports highlight where chromium compounds contained in leather items have exceeded permitted limits. These substances do not necessarily exist in chrome tanning processes, although they may arise depending on the method and the materials used. However, the main point that is often overlooked relates to the main chemical Chromium III which is used around the world for tanning majority of leather. Chromium III is commonly found in most animal or plant tissue and is not a danger to health.
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The peculiar mechanical properties of leather depend on the hide composition, a dense collagen feltwork. Unfortunately, due to their proteic composition, rawhides may undergo microbial attack and biodeterioration. Over centuries, different processes and treatments brining, vegetal or chrome tanning, tawing, etc. Nevertheless, even present-day rawhides are subjected to biological colonisation, and traces of this colonisation are clearly shown in Chrome III tanned leathers in the wet blue stage , with obvious economic damages.
The colonisation traces on tanned leathers consist of isolated or coalescent red patches, known as red heat deterioration. Parchments are rawhide products, too; they derive from another manufacturing procedure. Even parchments undergo microbial attack; the parchment biodeterioration seems comparable to leather red heat deterioration and is known as purple spots.
Recently, an ecological succession model explained the process of historical parchment purple spot deterioration; the haloarchaea Halobacterium salinarum is the pioneer organism triggering this attack. The marine salt used to prevent rawhide rotting is the carrier of haloarchaea colonisers Migliore et al. A bioinformatic comparison between chrome tanned leather vs.
Almost all human cultures have exploited the unique properties of rawhide for millennia, developing specialised techniques to take profit from this readily available material. These properties depend on its complex structure, consisting predominantly of a dense collagen fibre network. This network is composed of hierarchical substructures molecules, fibrils, fibres forming the collagen tissue, a two-dimensional feltwork stabilised by molecular cross-links.
Denaturation, oxidation and hydrolysis unhinge this hierarchical structure Badea et al. The most striking feature of leather is the ability to withstand repeating flexing without failure Ward, , and this useful feature is gained by processing hides through several techniques Kite and Thomson, Chrome III tanning is the present-day dominant method in leather manufacturing Saxena et al. These special features have substantially contributed to the success of the leather industry.
Rawhides, due to their animal origin, have a high tendency to undergo biodeterioration. A high amount of salt NaCl is required to inhibit biodeterioration due to the growth of heterotrophic, environmentally available bacteria. Unfortunately, even nowadays, chrome tanned leathers often show signs of biodeterioration, identified as red heat discolouration since by Jordon-Lloyd and Bergman Bergman, ; Jordon-Lloyd, The red heat deterioration consists of isolated or coalescent red patches, clearly evident in the wet blue stage of the Chrome III tanning process Figure 1A.
Photos by NP. Another rawhide product, parchment, shows signs of biodeterioration similar to the red heat deterioration. A frequent alteration found in ancient parchment is the so-called purple spot deterioration Figure 1B. Purple spots are responsible for parchment discolouration and detachment of the superficial layer in the most colonised areas Migliore et al.
Two recent studies shed light on the dynamics of the purple spot deterioration by analysing four historical parchments kept at the Vatican Secret Archive Migliore et al. The studies gave interesting insights into the process by identifying and demonstrating a microbial heterotrophic succession, devoted to the complete degradation and recycling of organic matter.
The succession, triggered by the halophilic Archaea, Halobacterium salinarum , responsible of the deterioration, made clear that salting of hides was the primum movens of the entire process Migliore et al. The first phase is predictable, mainly driven by the process of rawhide salt-curing, and it is common to all the damaged parchments. In fact, the marine salt used for salt-curing is responsible for conveying halophilic and halotolerant microbes adhering to salt micro-crystals.
Furthermore, marine salt determines a salty environment in the hides, limiting the growth of almost all heterotrophic colonisers of the rawhides. Conversely, colonisers of the long lasting second phase of parchment heterotrophic succession which leads to the complete degradation of the collagen are unpredictable, with the biological attack being driven by randomly selected microbes from those available in the environment.
Hence, these microbes change with the individual history of each parchment. This study focused on three main goals: i definitive identification of the microbial agents of the red heat deterioration in chrome tanned leathers; ii effects of colonisation on the stability and integrity of Chrome III tanned leathers; and iii comparison between parchment purple spots and red heat deterioration agents.
To these aims, we used a multidisciplinary approach. Furthermore, updated bioinformatic and statistical analyses were used to compare the microbial colonisers of ancient parchments and present-day tanned leathers. Leather samples were only bovine and included both red damaged tanned leather samples DTLs and undamaged tanned leather samples UTLs.
Rawhide samples included bovine rawhide BRH and sheep rawhide SRH samples, which were included in the study as a further control, as all BRHs are routinely and systematically salt-cured.
Both industrial and commercial alimentary salts were used. Solid M97 medium was also prepared. As described before, turbidity and reddish colour of medium indicated Haloarchaea growth, which were measured as total count. To have a reference for haloarchaeal growth, H. A piece 0. The NGS output showed significant differences among the communities of the three sets of samples, better highlighted by the taxonomical assignation of the operational taxonomic units OTUs and the relative frequencies of the different microbial phyla and orders.
Briefly, raw DNA sequencing data in the form of full. The taxonomic annotations were used to compare the microbial communities of the different samples; principal coordinates analysis PCoA plots were generated on Bray—Curtis distance metrics. Only 3 OTUs 72 sequences were unclassified, 4 were mitochondria and 2 chloroplasts 91 and 43 sequences, respectively. The complete set of assembled 16S RNA gene sequences obtained in this study has been deposited in GenBank under the study accession no.
Raman analyses were performed on both the pigments of alive haloarchaea and the pigments extracted from red damaged tanned leathers DTLs. The pigments of the alive haloarchaea were directly analysed. Pigments of the red damaged tanned leathers DTLs were chemically extracted from the red patches. The induced hydrothermal denaturation of the collagen populations in the chrome tanned leather samples was investigated by means of the LTA technique, as already described in Migliore et al.
Standard cultivation methods in liquid M97 allowed increasing reddening and turbidity of the media due to H. The reference strain H. To standardise differences among samples, the dataset was normalised to the lowest common depth of 62, sequence reads per sample sample UTL 3 by random subsampling. The rarefaction curves, built to evaluate differences and efficiency in the sampling effort, confirmed that the sequencing coverage was good Supplementary Figure S1.
PCoA based on Bray—Curtis distances shows clear patterns of separation in the microbial composition associated to the three replicates 1, 2, 3 of each sets of samples, including red damaged tanned leather DTL and undamaged tanned leather UTL , and bovine rawhides BRHs. Number and percent of OTUs are reported. Only 3 OTUs 72 sequences were unclassified, 4 were mitochondria, and 2 chloroplasts 91 and 43 sequences, respectively.
The class Halobacteria were prevalent in both BRH Halobacteria were entirely represented by the order Halobacteriales Among bacteria, Proteobacteria and Firmicutes were observed in all samples. Gamma-Proteobacteria were dominant in BRH Bacilli were mainly found in DTL The Figure 5 shows how OTUs are partitioned among the three sets of samples.
Composition of the microbial communities, as percentage of sequences per taxonomic group, in rawhide BRH , red damaged tanned leather DTL , and undamaged tanned leather UTL. In Figure 6 , Raman spectra of reddish pigments extracted from a red colonies of H. The pigments extracted from e red damaged tanned leathers DTL were directly analysed.
According to the literature Vaskova, , the main peaks in the range — cm —1 are due to the presence of chromium used in tanning. Raman spectra of red colonies deriving from a H. As shown in Figure 7 , the LTA analysis of the collagen hydrothermal denaturation process in red damaged tanned leathers DTL and UTLs did not show any differences in the temperature of the peaks T d This indicates that the micro-structural chemical stability and its homogeneity are the same for the two samples.
In this study, the dynamics of red heat biodeterioration of Chrome III tanned leathers has been revealed by unequivocally identifying the microbial responsible — haloarchaea, mainly H.
Salt has been unequivocally demonstrated as the source of the halophilic microorganisms; these microbial colonisers of the rawhides, indeed, are absent in the leathers cured with sterilised salt.
In this study, the metagenomic analyses demonstrated that all the samples which had been salt-cured with industrial salt, i. They were present, at a very low percentage, even in UTL 0. The standard cultivation methods, with the selective medium M97, demonstrated the presence of live H. Hence, the salt used since ancient times to preserve the hides by inhibiting the growth of environmental microbes because of the high salinity is the reservoir and the vehicle of the Halobacteriales colonisers.
Haloarchaea-contaminated industrial salt triggers their slow growth on the surface of the hide on the flesh side. As shown in Supplementary Figure S3 , a transversely cut sample of BRH clearly shows that, after 3 months of incubation in the lab, the reddish discolouration is limited to the superficial layer of the flesh side. Conversely, both sterilised salt and sterilised salt-cured rawhides did not contain live H. In fact, sterilised salt-cured hides did not show any growth of haloarchaea Supplementary Figure S2.
The Raman spectroscopy confirmed these data by detecting the halobacterial bacteriorhodopsin, the purple transmembrane protein containing retinal; these pigments were clearly found in the red patches of red damaged tanned leathers, where NGS demonstrated the presence of Haloarchaea, just as in the colonies harvested from standard cultivation methods of industrial salt-cured leather and industrial salt samples.
These results unequivocally confirmed that haloarchaea are responsible for red heat deterioration and that salt is their vehicle of colonisation. As expected, this result demonstrated that chrome tanning, among other effects, is able to tear down the microbial load of the hides.
In the last decades, red heat deterioration of hides has been investigated, although a definitive answer had never been found — Anderson tried to preliminarily characterise the halophilic microbes, from red deteriorated salted hides, by standard microbiological techniques; [opetwcite]B6,B5[clotwcite] Birbir et al. NGS also revealed all the other microbial colonisers of rawhides and tanned leathers.
The microbial colonisers, accounting for OTUs, were differently partitioned among the three batches. In fact, the red damaged and UTL harbour different communities: the unique OTUs in red damaged samples are one order of magnitude higher than in undamaged tanned ones, as the colonisation itself probably triggers a microbial succession which allows a higher colonisation rate, by producing a different environment in the damaged areas.
This progressive modification of the microbial community must depend on the presence of salt: rawhides are the saltiest environment of the three sample sets due to routine salt-curing preservation.
Marine salt is produced in saltworks based on evaporation ponds — shallow, lined earthen basins in which concentrate evaporates naturally as a result of solar irradiation.
Nevertheless, it could be hypothesised that the salt-curing process may allow the entrance and embedding inside the hide of microscopic salt crystals carrying Halobacteria. On these microcrystals they could persist, and the red heat would occur wherever the salt-associated Halobacteria grew to be later killed and lysed, in situ , by the treatment, the lysed Halobacteria colonies being responsible for the red heat discolouration.
The rare DNA traces of Haloarchaea found even in undamaged samples may derive from the very high abundance of haloarchaea in the colonised rawhides, which can be a source of DNA contamination for the entire tannery. The DTL and UTL shelter different communities; hence, a different structural damage of collagen fibres due to the microbial colonisation was hypothesised in the two leather batches. In addition to the identical mean thermal stability between the two kinds of sample, proved by the same T d values, the same width of the peaks 8.
The tanning process makes high and homogeneous the stability of collagen fibres by creating new crosslink bonds in the collagen triple helix, regardless of the initial and superficial microbial attack Figure 7. Recently, Migliore et al. Parchment purple spots have been shown to be triggered by haloarchaeal colonisation Migliore et al.
Horween Leather Company was founded in For more than years and five generations our goal has been to make the world's best leather. Making the best means doing lots of little things right. It means never mistaking fastest or cheapest with the best. It means always using formulas that do not cut corners, and choosing components strictly for their quality.
Table of Contents
A system and method for a chromium recovery process for recovering chromium from byproducts resulting from a tannery process. A system and process for solubilizing chromium contained in the oil byproduct into the remaining water content within the oil and extracting the water from the oil with the chromium sufficiently solubilized in the water such that the chromium content in the oil is sufficiently reduced below hazardous levels. This technology relates generally to the tanning process and, more particularly, to recovery of chrome from a tannery process. Traditionally, tanning used tannin, an acidic chemical compound found in oak and fir trees from which the tanning process draws its name. Tanning leather is a process which permanently alters the protein structure of skin.
Leather production processes
The peculiar mechanical properties of leather depend on the hide composition, a dense collagen feltwork. Unfortunately, due to their proteic composition, rawhides may undergo microbial attack and biodeterioration. Over centuries, different processes and treatments brining, vegetal or chrome tanning, tawing, etc. Nevertheless, even present-day rawhides are subjected to biological colonisation, and traces of this colonisation are clearly shown in Chrome III tanned leathers in the wet blue stage , with obvious economic damages. The colonisation traces on tanned leathers consist of isolated or coalescent red patches, known as red heat deterioration. Parchments are rawhide products, too; they derive from another manufacturing procedure.SEE VIDEO BY TOPIC: A Tour of Horween Leather
Leather is almost more deeply ingrained into the world of raw denim than denim itself. You can find it on the patch of your jeans, on the belt you use to hold them up, on the shoes on your feet, and even occasionally backing the rivets that hold your jeans together. Leather is made from the skin of animals such as cows, horses and sometimes also exotic animals like ostriches, snakes, or crocodiles. The different types of animals have different types of hides with different properties such as their appearance and durability, making them desirable for various purposes in products such as garments, footwear, accessories, or furniture upholstery. For a skin to be turned into a hide that can be used in the garment industry, one must first prepare and conserve it. Stabilization of these proteins is necessary in order to prevent the skin from breaking down and naturally decomposing. To prevent this from happening humans have, since the Stone Age, made use of tannins and their antioxidant capabilities, to make the skin resistant to the protein cleavage by enzymes rotting and thus conserving the leather. A closer look at an aged vegetable tanned leather and the clusters of collagen.
The Portland State University EcoPol project looks at the intersection between ecological and economical topics with the goal of changing readers thoughts, behaviors and actions. Four times a year a separate website is developed and launched in support of a particular topic, and the main goal is this - how can we encourage people to take action to make policy change which improves sustainability? This site addresses progressive leather tanning for a cleaner environment. The hides are then stored in temperature-controlled cool rooms and preserved in salt, and once ready for processing, are sorted by quality and weight.
General Profile Debra Osinsky. Tanning and Leather Finishing Dean B. Fur Industry P. Footwear Industry F. Conradi and Paulo Portich. Technological choices for treatment tannery effluents. Animal furs and leather from tanned animal hides and skins have been used to make clothing for thousands of years. Fur and leather remain important industries today. Fur is used to produce a variety of outer garments, such as coats, jackets, hats, gloves and boots, and it provides trim for other types of garments as well. Leather is used to make garments and can be employed in the manufacture of other products, including leather upholstery for automobiles and furniture, and a wide variety of leather goods, such as watch straps, purses and suitcases.
US20150167108A1 - Method of recovering chrome from a tannery process - Google Patents
Until the 19th century, there was little development in the tanning process. While there was some use of alum aluminium salts and other tanning methods , vegetable tanning was the most prevalent. However, it was an American chemist called Augustus Schultz who first patented the chrome tanning process. In the following decades, chrome tanning became the most common and dominant form of tanning. One of the main reasons why it was adopted so rapidly is that the process was much faster than vegetable tanning. The invention of chrome tanning coincided with the discovery of the fatliquoring regreasing process and also the development of synthetic dyes. Together these changes to the chemistry of leather production led to chrome tanning becoming the preferred method. Chromium salts belong to the group of mineral tannins. Immediately after tanning, the leather is still wet and is tinged with blue, hence it is also referred to as wet blue. Chrome tanning with chromium III salts accounts for around 85 percent of global leather production as per
The peculiar mechanical properties of leather depend on the hide composition, a dense collagen feltwork. Unfortunately, due to their proteic composition, rawhides may undergo microbial attack and biodeterioration. Over centuries, different processes and treatments brining, vegetal or chrome tanning, tawing, etc. Nevertheless, even present-day rawhides are subjected to biological colonisation, and traces of this colonisation are clearly shown in Chrome III tanned leathers in the wet blue stage , with obvious economic damages. The colonisation traces on tanned leathers consist of isolated or coalescent red patches, known as red heat deterioration. Parchments are rawhide products, too; they derive from another manufacturing procedure. Even parchments undergo microbial attack; the parchment biodeterioration seems comparable to leather red heat deterioration and is known as purple spots. Recently, an ecological succession model explained the process of historical parchment purple spot deterioration; the haloarchaea Halobacterium salinarum is the pioneer organism triggering this attack. The marine salt used to prevent rawhide rotting is the carrier of haloarchaea colonisers Migliore et al.
Warson , C. This volume discusses latices in surface coatings in regards to diverse applications. These water-based latices are playing a far greater role in many applications and match the growing concern over environmental safety.
Conventional chrome tanning methods employed in the leather processing industry subject the hides and skins to treatment with a wide variety of chemicals and passage through various unit operations. All this involves an enormous amount of time and they contribute to an increase in COD, chlorides, sulfates and other mineral salts, which end up as effluent. But, perhaps more alarmingly, the process uses profuse quantities of water in areas where there is rapid depletion of ground water.
Account Options Login. Bibliography of Agriculture , Volume 30,Masalah Halaman terpilih Halaman Judul.
Они приподнимали головы, чтобы разглядеть инопланетных гостей. Ярко-красные и желтые животные с восемью ногами и рачьими клешнями несли толстые зеленые стержни через перекресток в пятидесяти метрах от Ричарда и Николь. Конечно, повсюду дюжинами.