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Swelling vs. plumping / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 26-28 Titre : Swelling vs. plumping Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 26-28 Langues : Anglais (eng) Catégories : Chaulage Collagène Cuirs et peaux Eau Gonflement (physique) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Examination of any book on leather science will always talk about the collagen swelling effects seen at the secondary or tertiary level of protein hierarchy. The exact description and the prominence of which types of swelling exist in the material at specific parts of the process cycle can be left up to the academics to debate. As with most science, the frustration that exists between technologists and the theoreticians are real. Like many leather scientific theories, the facts (that usually make perfect sense) and the reality seen in the liming or pickle drum are often confusing. A common example of this is the description of the leading type of swelling that is seen during liming. The controls that the tanner uses to overcome this swelling often appear to be contradictory, or at the very least do not seem to equate to the effects that one would expect given the theory. Note de contenu : - Revision of swelling : Lyotropic - Electrostatic - Structure hierarchy - Water - Plumping - Fig. 1 : A schematic representation of how the collagen triple helix opens when experiencing swelling effects - Fig. 2 : At the fibre-bundle, or fibre level, the influx of capillary water (or maybe even bulk water) also has a profound effect, resulting in the hide and skin increasing size tremendously (plumping) - Table 1 : Collagen has various water associations (Taken from Bienkiewicz, 1983) En ligne : https://drive.google.com/file/d/1HEX9X3hoxVK4Icf3UU1hHuaSqnmIqYgU/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33443 [article]

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Leather property : looseness / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 30-33 Titre : Leather property : looseness Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 30-33 Langues : Anglais (eng) Catégories : Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux -- Propriétés physiques Cuirs et peaux de bovins Relachement (mécanique) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The fine or coarse wrinkles that appear on the grain side of a leather bent concavely are known in the tanning community as looseness. A leather with the absence of wrinkles will be described as a tight-grained leather. A leather with large, coarse wrinkles that develop particularly with time will be described as loose-grained leather. The leather technologist focusses on two main leather-maldng layers : the grain (corium minor) and the corium (corium major). The transition from the grain to the corium is hypothetically dealt with by a zone known as the grain-corium junction. Many scientists attribute this zone, in bovine leather, as the horizontal zone at the base of the hair follicles. Many animal types exhibit differing degrees of looseness and this is often due to the presence of dermal fat. The removal of that fat during the leather-making process will leave the material porous and prone to loose-grain in the final leather article. The density and proximity of the leather fibres also plays a major role in the natural tendency/ aversion to loose-grain. The belly/axillae region of the hide and skin (a naturally loose structured area) tend to have poor grain tightness. An exaggerated opening up during the beamhouse will increase the incidence of the looseness, particularly in some animais (e.g. buffalo). The heart of the looseness problem is twofold : the looseness can develop during wear, with extremes including delamination of the grain away from the corium; the leather is already loose - but unevenly loose - making the cutting of the leather article difficult to match (in terms of consistent visual pattern). Many leathers, such as floating grain leathers and other mill-grain effects, are intentionally loose in grain structure. Note de contenu : - Beam theory - Looseness testing - Fig. 1 : Tigh-grained leathers bending in on the grain. Blue arrows showing long extension and yellow arrows showing compression of the grain. Modified from Haines and Barlow (1975) - Fig. 2 : Loose-grained leathers bending in on the grain. Blue arrows showing lower extension and yellow arrows showing compression of the grain. Modified from Haines and Barlow (1975) - Table 1 : An outline of some of the techniques to measure leather tightness En ligne : https://drive.google.com/file/d/1b_KDRs5_dLuT-7RDDJlW4ZGIAgJMctkI/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33621 [article]

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Waterless processing / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 40-42 Titre : Waterless processing Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 40-42 Langues : Anglais (eng) Catégories : Eau -- Consommation -- Réduction Tannage -- Aspect de l'environnement Tannage au chrome Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : ILM Consultant Technical Editor Karl Flowers looks at three water-saving processes in chromium tanning and the importance of conserving this precious resource. Note de contenu : - Xorbs - Qualus - Waterless chrome tanning (WCT) - CLRI - DriTan - Ecco En ligne : https://drive.google.com/file/d/1U_eC2Y33eTJETJzrNxTT29UuP0gC4wVt/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33622 [article]

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Shifting towards a circular economy is the next step in the industrial revolution / Frank Brouwer in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 44-45 Titre : Shifting towards a circular economy is the next step in the industrial revolution Type de document : texte imprimé Auteurs : Frank Brouwer, Auteur Année de publication : 2019 Article en page(s) : p. 44-45 Langues : Anglais (eng) Catégories : Développement durable Économie circulaire L'économie circulaire est une expression générique désignant un concept économique qui s'inscrit dans le cadre du développement durable et s'inspirant notamment des notions d'économie verte, d’économie de l'usage ou de l'économie de la fonctionnalité, de l'économie de la performance et de l'écologie industrielle (laquelle veut que le déchet d'une industrie soit recyclé en matière première d'une autre industrie ou de la même). Son objectif est de produire des biens et services tout en limitant fortement la consommation et le gaspillage des matières premières, et des sources d'énergies non renouvelables ; Selon la fondation Ellen Mac Arthur (créée pour promouvoir l'économie circulaire1), il s'agit d'une économie industrielle qui est, à dessein ou par intention, réparatrice et dans laquelle les flux de matières sont de deux types bien séparés ; les nutriments biologiques, destinés à ré-entrer dans la biosphère en toute sécurité, et des intrants techniques ("technical nutrients"), conçus pour être recyclés en restant à haut niveau de qualité, sans entrer dans la biosphère Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : 0ur earth is exhausted. Today we take more from nature's resources than our planet can provide. Clearly, that fact alone means we have to stop using finite resources and look for ways to reduce the environmental footprint of the leather industry. Therefore, it is important to focus on redesigning our products and processes by using responsible chemistry and resourcing. In this article, I share my thoughts on what I see as the unavoidable transition to a circular economy, and what companies can do to contribute to a better planet. As a Green Technology Chemist at Stahl, I spend my time thinking about how we can redesign products and processes so they align with the circular way of thinking. How we can make smarter and better use of raw and semi-finished materials, reducing our impact in the value chain, while supporting our customers with possible solutions with regard to prolonged usage, reuse, refurbish and recycling of their products. Sustainability is a broad topic, but the keywords that recur in my work include things like "bio-based materials", "closed loop materials", "circular economy", "emission reduction" and the replacement of toxic chemicals and processes. Note de contenu : - New models, technologies and cooperation - One step at a time - Closing the loop in a world of complex products - Renewable raw materials enhance our chemical toolbox - Collaboration is the key to a successful transition - Shift towards evenm ore sustainable materials - Find the world at your feet En ligne : https://drive.google.com/file/d/1PeXVuwbkrb_OCiDkW_qURys6hnxXIRiQ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33623 [article]

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Grain crack and burst strength / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 54-58 Titre : Grain crack and burst strength Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 54-58 Langues : Anglais (eng) Catégories : Anisotropie Collagène Cuirs et peaux -- Propriétés mécaniques Essais de résilience Essais dynamiques Lubrification Matériaux -- Fissuration Résistance à l'éclatement Résistance à la fissuration Stratigraphie Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leather is a collagen skeleton that has chemical groups attached to it, which can either enhance its natural strength or annihilate it. Collagen is a rope-like network, three-dimensionally woven into a net-like mesh. The rope-like fibres can be dispersed so that they operate more independently, or they can be crowded together to move with restriction, causing them to feel dense and full. The spaces between the fibres and fibre bundles can be filled with interstitial materials that again restrict the freedom of fibre movement and, quite importantly, they can lower the porosity of the leather. Dense fibre structures begin to operate like reinforced concrete, the central fibre and surrounding packing material begin to co-operate as one unit and the collective strength they have is significantly higher than one fibre's individual strength. The lubrication (plasticisation) of the fibres is also critical to material strength. The individual fibres must be made to be flexible to ensure movement and strength. The opposite effect - adding a retan to the fibre that makes it more brittle the opposite of the lubricating effect mentioned above. Leather is anisotropic, topographically and stratigraphically. The focus of this article will be on the stratigraphic anisotropy - the phenomenon that considers fibre size and behaviour differences, as one transits from the grain to the flesh. Note de contenu : - Crack and burst testing - Brittle grain - The influence of tanning - Lubrication of the grain - Fig. 1 : A hand powered lastometer - the apparatus used for ball and grain burst - Fig. 2 : The clamp assembly of the lastometer showing a grain rupture (arrow) - Table 1 : Current industry methods that test the ability of a leather to resist the grain from cracking En ligne : https://drive.google.com/file/d/133e7dlqFVeWW24uJR5TwZAZgx7Cbi1vl/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33624 [article]

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Upgrading poor leathers / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 64-68 Titre : Upgrading poor leathers Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 64-68 Langues : Anglais (eng) Catégories : Cuirs et peaux -- Défauts Défauts -- Réparation Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The central philosophy on how low-quality raw material can be converted into a higher quality relies on some visual alterations of the leather surface. With ever decreasing raw material quality, the challenge is for tanners to become more imaginative than ever to try and improve the perceived quality of the leather. Of course, if better quality raw material can be purchased, then the tanner's job becomes easier. The simple fact of the perception of surface quality is this: the hide/skin surface is normally perceived as high quality if the light from a source shines onto the grain of the leather. The grain will reflect the light to the eye (or observer) if there is no impedance of that light beam. If any disfiguration of the hide/skin surface takes place that interrupts the pattern of the grain, then the eye will immediately be drawn to that interruption. It goes without saying that the larger the interruption of that pattern, the more visible the mark will be. Invisible marks are characterised by small marks, or by marks that have been able to heal as to resemble the pattern of the grain before the disfiguration took place. The disfiguration of the grain could have been the result of any living animal damage, the damage obtained from the slaughter, or from the leather manufacturing process. Some animais are more prone to marking, and all animais will heal differently. Some hides/skins will seem more scarred compared to animais who have been through the same disfigurement. The degree of healing may also play quite a large role in the prominence of the scar tissue. Note de contenu : - Tanning - Other wet processing - Filling - Opacity - Texture - Two-tone - Enhancement - Fig. 1 : An open defect is filled using filling compounds to produce a smooth surface. Sometimes air is trapped in the infill, which can pose problems - Fig. 2 : The principle of opacity - the visible marking is cosy to spot due to a lack of interference, while B shows the placement of an opaque chemical makes a marking invisible - Fig. 3 : A healed scar is hidden using the clever use of a texture which blends the prominence of the mark in with a pronounced grain pattern En ligne : https://drive.google.com/file/d/1AqQ7TErJPW-JRFX2dRqycMKA8gQnaW6Y/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33625 [article]

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Grading and sorting / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 102-107 Titre : Grading and sorting Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 102-107 Langues : Anglais (eng) Catégories : Cuir et peaux -- Tri Cuirs et peaux -- Classement Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The quality of raw materials going into leather manufacture has always been out of the control of the tanning industry. 99% of raw hides and skins that enter the leather industry are a by-product of the meat industry. The farmer does very little to ensure that the surface quality of the animal hide/ skin, beyond the usual practices of good farm management and animal welfare care, are improved. There is little incentive, financial or other, for the farmer to invest time and capital in hide/skin improvement. Consequently, global material quality has been declining for the past 20 years. Increasing numbers of surface marks as a result of natural farm influences are seen. The abattoirs can also be a source of surface marks if the operators have poor training and lack experience. Cost cutting in the meat industry will deprioritise investment in training and capital investment that can improve flay quality. In some tanneries, there is also a consistent lack of knowledge and quality control that can help in the prevention of tannery related surface marks. A general de-skilling of the leather-making industry and leather article manufacturing result in higher than normal problems due to the general care, consideration, and skill of the operators. Note de contenu : - Balancing animal welfare with surface quality - Animal signatures versus making plastic - Types of leather surface marks - Open versus closed marks - Grading and sorting stages in the tannery - Sorting routes - Grading systems (tanners and 5-point grading) - Grading as a sliding scale - Cutting coefficients - Non-pattern and pattern grading - Fig. 1 : A schematic representation of the locational variations of types of marks on an ostrich skin - Fig. 2 : Material separation positions and provenance through to wet-blue-sorting - Fig. 3 : Material grading and sorting decisions defining material down specified routes for better material - Fig. 4 : material grading and sorting decisions defining material down specified routes for worse quality material - Fig. 5 : Material grading and sorting decisions defining material down specified routes for splits - Fig. 6 : An example of the pattern used for the inside quarter of a shoe - Table 1 : A typical tanner grading system En ligne : https://drive.google.com/file/d/1NU12nq_g256TD-9132FIkRKxO8-9w7BR/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33626 [article]

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Neutralising chemicals / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 108-111 Titre : Neutralising chemicals Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 108-111 Langues : Anglais (eng) Catégories : Neutralisants (chimie) pH Post-tannage Wet-blue (tannage) Peau tannée au chrome (le chrome donne une couleur bleue) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : In the post tanning operations of a tannery, a heavy dependence is laid on the pH values of the wet end stage. It has been known rince the acceptance of chromium as a viable tanning method that the post tanning operations play a large role in helping to decide the final properties of the resulting leather. For a chemist trained outside of the tanning industry, the term neutralisation means to take the bath pH value from either an alkaline or an acidic value to the neutral point (pH 7). This is not what tanners mean when they refer to neutralisation (the pH is very seldom pH 7). Others will refer to neutralisation as to the neutralisation of electrical charge in the leather collagen. Again, the state of electrical neutralisation is very seldom complete. Tanners seldom get to the iso-electric point, IEP (see Table 1), but the act of neutralising is certainly something that does take place. The obvious way forward is not to refer to the operation in chromium tanned leather as neutralisation, but rather as neutralising. Another version of neutralising is taking the leather, electrically, to the IEP (neutralisation) and beyond, see Figure 1. This is often referred to as anionisation and is a common tactic in the preparation of water-resistant leathers. Another common anionisation or true neutralisation is seen in the manufacture of wet-white leathers or in vegetable tanned leathers. Note de contenu : - Objectives of neutralising - Can we leave neutralising out ? - Types of chemicals - Table 1 : The theoretical iso-electric point pH values (taken from Sharphouse, 1989) - Fig. 1 : Zeta potential showing the charge according to pH value - Fig. 2 : Chemical groups of neutralising syntans and agents - Fig. 3 : Buffering solution pH profile En ligne : https://drive.google.com/file/d/12ig4wDHBKAasa3LrNUY5jbnVfd6NFnYf/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33627 [article]

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