Content: Acid attacks are a global problem: from 2011 to 2016 there were 1,464 incidents involving a corrosive substance in London alone. The most common chemicals used in these attacks are sulfuric, nitric and hydrochloric acids. Concentrated solutions of strongly alkaline substances including sodium hydroxide and sodium hypochlorite are also used. Current first-aid advice suggests diluting the exposed area with water and transfer to a hospital for further treatment. An immediate neutralisation treatment is avoided as incorrect identification of the corrosive could worsen the damage. In addition, there are concerns the enthalpy of solvation and neutralisation causes secondary burns. These limitations demonstrate the need for an amphoteric neutralising treatment with a low enthalpy of neutralisation. Aqueous formulations of natural water-based surfactants with natural plant-based substances have been trialled as neutralisers of sulfuric acid, sodium hydroxide and sodium hypochlorite. pH titrations demonstrated that the natural formulations are amphoteric, capable of effectively neutralising acidic and alkaline corrosives with minimal heat of neutralisation and no gas evolution. In addition, the studies have shown that the formulations can reduce oxidisers such as sodium hypochlorite. The experiments compared intact collagen with attacked but untreated collagen and collagen that had a corrosive applied but followed by treatment at different time intervals. Scanning electron microscopy (SEM) showed the reaction with concentrated sulfuric acid is rapid; significant collapse and gelatinisation of the fibre structure was observed within 5 seconds. Pigskin was utilised to model human skin: the observations demonstrated the importance of the epidermis in protecting the skin from chemical damage. Five minutes exposure to sulfuric acid, sodium hydroxide and sodium hypochlorite did not penetrate the epidermis, although damage was observed. The formulations of natural products recently tested at the University of Northampton have been shown to mitigate secondary chemical burns, whereas treatment with water alone resulted in secondary burns due to residual corrosive in the skin structure not being neutralised. The trials indicate that the product could be usefully applied by first responders and emergency services personnel. Take-Away: The findings have the potential to change current first-aid reccomendations by demonstrating an applicable neutralisation mechanism, whereas neutralisation with sodium bicarbonate has been shown to cause further damage to skin structure via gas evolution. Formulations of natural products have been shown to mitigate secondary chemical burns, whereas treatment with water resulted in secondary burns due to residual corrosive in the skin structure not being neutralised. Trials indicate these natural formulations could be usefully applied by first responders and emergency services personnel.

Content: Surfactants of different ionic nature are used in virtually all steps of leather production. In processes like soaking, degreasing and wool washing, tremendous amounts of surfactants are applied and to a great extent discharged into the tannery effluent. In order to improve the sustainability of leather processing, there is a constant search for more efficient, environmentally friendly emulsifiers, which give superior results already in smaller usage amounts. By introduction of propylene oxide based lipophilic linkers between the hydrophilic head and hydrophobic tail, the wetting and emulsion capability of a surfactant can be increased significantly. The resulting surfactants, so called extended surfactants, are generally more hydrophobic and have an extended tail, which reaches further into the oil face without scarifying the water solubility, what would be the results when increasing the alkyl chain. Thus, the use of lipophilic linker changes the emulsion on a structural level. Extended surfactants have been found to be superior in various applications, including textile laundry or tertiary oil recovery. In the present work, the efficiency of various types of non-ionic and anionic extended surfactants is demonstrated in various stages of leather making. Model surfactants with lipophilic linkers are compared to their analogues without linker molecules. In many processes, significantly improved surfactant efficiencies are found making this group of molecules an interesting topic for further exploitation. Take-Away: Significantly improved surfactant efficiency for more sustainable leather processing

Content: The intrinsic structure significantly influences the mechanical properties of leather. In consequence, knowledge of leather’s hierarchical structure is essential in order to find the most suited leather for specific application. Leather structure based parameters are of major importance for both manufacturing and leather processing industries. In this respect, intensive structure investigations have been subjected in continuous research work. Quantitative image analysis combined with stochastic micro-structure modelling and numerical simulation of macroscopic properties is a promising approach to gain a deeper understanding of complex relations between material’s micro-structure geometry and macroscopic properties. Key ingredient is a reliable geometric description provided by the quantitative analysis of 3D images of the material micro-structures. For leather, both imaging and image analysis are particularly challenging, due to the multi-scale nature of the leather’s micro-structure. Scales in leather are not well separated. Previously, high resolution computed tomography allowed 3D imaging of purely vegetable tanned leather samples at micro- and submicro- scale. Segmentation of leather structure as well as of typical structural elements in resulting image data is however hampered by a strong heterogeneity caused by lower scale structural information. The first method for automatic segmentation of typical structural elements at varying scales combined morphological smoothing with defining and iteratively coarsening regions using the waterfall algorithm on local orientations. It yields a hierarchical segmentation of the leather into coarse and fine structural elements that can be used to analyze and compare the structure of leather samples. Size and shape of the structural elements as well as their sub-structure yield information, e. g. on undulation, branching, thickness, cross-sectional shape, and preferred directions. In order to compare the micro-structure of leather samples from various body parts or even species, the segmentation has to be applicable without extensive pre-processing and parameter tuning. Robustness can be gained by applying smoothing methods that are adapted to the goal of defining image regions by similar local orientation. The challenge is that the space of fiber orientations in 3D is not equipped with an order. Motivated by a recent approach for nevertheless defining erosion and dilation on the sphere, we suggest new definitions for these morphological base transformations on the space of directions in 3D. We present segmentation results for 3D images of leather samples derived by these new morphological smoothing methods. Take-Away: The intrinsic structure significantly influences the mechanical properties of leather. Leather’s hierarchical structure can be analyzed by quantitative 3D image analysis combined with stochastic micro-structure modelling. Segmentation results for 3D images of leather samples derived by new morphological smoothing methods.

Content: The removal of hair from a hide or skin by dissolving it with a mixture of lime and sulfide is a fundamentally understood feature of leather technology. Or is it? For a long time, it has been accepted within the leather literature that, in water, sulfide may be present as either hydrogen sulfide (H2S), hydrosulfide (HS-) or sulfide (S2-), depending on the pH. pH < 6 6 < pH < 12 pH > 12 H2S(aq) ⇌ HS-(aq) ⇌ S2-(aq) The generally accepted mechanism of hair burning is sulfide attack at the cystine disulfide linkages in keratin. Also, it is believed that the unhairing reaction only proceeds at an appreciable rate in the presence of the dianionic S2- species, because that fits with the technological observation that unhairing reactions only proceed at pH greater than 12. However, recent publications have provided substantive proof that the S2- species does not exist in aqueous media at any pH: researchers were unable to observe any evidence of the S2- species in a solution of Na2S dissolved in hyper-concentrated NaOH and CsOH using Raman spectroscopy. The assigned second pKa for removal of the second proton has now been estimated to be 19, making the concentration of S2-(see below) vanishingly small. HS- ⇋ S2- + H+ There is a clear contradiction between the currently accepted mechanism for sulfide unhairing with the evidenced speciation of sulfide species in aqueous environment. Here the implications for this important process are discussed and possible alternative mechanisms postulated that fit with the new knowledge. Take-Away: It is a truism that we must understand the mechanistic principles of a process in order to control it. Here, we have a big change in thinking for ‘sulfide unhairing’, so it is vital that we understand the implications for leather science and leather technology of that change.

Content: In this study, different proportions 2.5%, 5%, 10% of aluminum sulfate were used as tanning agents during parchment production. The research was carried out on goat skin and also there were no usage of any tanning agents as control groups. Finished leathers have been exposed to ageing conditions. Before and after ageing color measurements on all finished leathers have been conducted with Konica Minolta CM-3600d brand spectrophotometer. The impacts of the aluminum sulfate utilized in the research on light fastness were also inspected by using an ATLAS-XENOTEST ALPHA+ test instrument. Visible whitening on the color of parchment was observeded when tanning process with aluminum sulphate was performed. Take-Away: -Aluminum sulfate has tanning effects -Aluminium gave white color to the parchment -Aluminum sulfate changed collagen structure.

Content: Leather and leather products are known for its durability and luxuries which makes it more unique among the other synthetic materials. Breathability and visco-elastic properties make leather unique choice of biomaterial. Utilization of leathers in marine based applications is limited owing to reactivity of leather towards salt and weather conditions. Moreover, the choice of raw materials and chemicals used during leather manufacture has greatly influence the properties of the leather. An attempt has been made to understand the influence of sea conditions on leathers. Conventional chrome tanned and vegetable tanned leathers were incubated in sea water and subsequently processed into post tanning to evaluate the physical properties. To understand, the leaching of chemicals, dyed leathers are incubated at different humidity and saline conditions. Interestingly, chrome tanned leathers found to be friendlier to marine conditions whereas, vegetable tanned leathers lead to leaching of chemicals. Furthermore, leaching of chromium is negligible, and crust leathers resulted in soft leathers. Prolonged exposure of chrome tanned leathers under salt stress leads to more softness. This might be due to saline stress to the skin matrix. Moreover, the computability of conventional leather chemicals were also tested using sea water. The research provides a new insight on fine tuning the chemicals to suit marine based applications. Take-Away: A new insight on fine tuning the chemicals to suit marine based applications.

Content: Quality of leather is deeply dependant on the origin of the livestock including breeding, transportation and slaughter. Ten years ago, the French leather industry have commissioned CTC, the French Leather, leather goods and footwear research centre to improve the quality of hides and skins. In order to improve raw material, a unitary link is required between the quality of leather and its origin that is to say the raw material. This was the beginning of a huge project: traceability of hides and skins through the supply chain, from breeding to wet-blue (and even leather). Data is captured from the animal’s ear tag at the point of slaughter which is then transfer on to a paper bar code. Hides and skins traders will then transfer definitively the code from the paper tag to the hides or skins thanks to an automatic high-pressure CO2 marking device on the hair side of the fresh or salted hide in the neck region. That unitary traceability is resistant to water, acid, alcalis, grease, solvents but also mechanical impacts such as splitting, shaving and even buffing. It is visible throughout all the process and fast enough. Once the permanent number code has been added, it can be visually or automatically read throughout the subsequent tanning process steps. The automatic code reader takes the algorithm of the number and the data is collected by mean of artificial intelligence. This technology has been implemented by several abattoirs, trader and tanners. Traceability is the essential tool for quality management throughout the supply chain. It helps the identification of the origin of defects for improvement and provides the origin of grade 1 hides and skins. This realistic industrial solution is a major issue for the leather industry whether it is for the improvement of quality or mastery of the supply chain and sustainability. Take-Away: In order to improve the quality of raw material, a unitary link is required between the quality of leather and its origin that is to say the raw material. This is the objective of that project: traceability of hides and skins through the supply chain, from breeding to wet-blue (and even leather) thanks to CO2 laser marquing.

Content: Nowadays, tannery pollution is of great concern worldwide. The unhairing and fiber bundle-opening processes contribute the majority of the pollution by the use of sodium sulfide and calcium hydroxide, which were proposed to be replaced by neutral protease combined with (potassium chloride) KCl, (lithium bromide)LiBr/1-allyl-3-methylimidazolium chloride([AMIm]Cl) in the present work. Proper amount of KCl can speed up the unhairing with the grain not destroyed by the neutral protease. Four methods for unhairing and fiber bundle-opening were used as follows: 1. Two steps in different floats as KCl/neutral protease unhairing, followed by LiBr/[AMIm]Cl for fiber bundle-opening; 2. Two steps in different floats as neutral protease unhairing, followed by LiBr/[AMIm]Cl for fiber bundle-opening; 3. One step in the same float as neutral protease for unhairing firstly and then LiBr/[AMIm]Cl for fiber bundle-opening. 4. One step in the same float as neutral protease/KCl for unhairing firstly and then LiBr/[AMIm]Cl for fiber bundle-opening. It was found that using neutral protease/KCl solution for unhairing and LiBr/[AMIm]Cl solution for fiber bundle-opening is the best in fiber bundle-opening at the liming process. Besides, all the methods used here are better than the traditional liming processes (C) from viewpoints of unhairing and fiber bundleopening. Take-Away: 1. The addition of potassium chloride can improve the stability of neutral protease solution. 2. The catalytic efficiency of the enzyme was improved because of adding potassium chloride can enhance the contact rate of neutral protease with substrate. 3. Ionic liquids have less hydrolysis of collagen and larger dissolution of polysaccharides.

Content: Soluble soybean polysaccharide (SSPS) is good in emulsification, and stable emulsion may be formed with the addition of SSPS in fatliquoring agents. In this paper, with wet blues as raw materials, after being retanned and neutralized, fatliquoring and filling up with SSPS were carried out at the same time, with different amounts of SSPS, i.e., 1%, 3%, 5%,7% in weight. The leather samples were dried at room temperature. The effects of SSPS amounts on the thickness, air permeability and water vapor permeability of the crust leather were studied. The tensile properties of the leathers filled by SSPS were analyzed. The results indicated that with increasing the amounts of SSPS, the thickness and the water vapor permeability of the leathers increase, while the air permeability decreases slightly. The maximum stress-strain capacity of leathers decreases with increasing the SSPS amount. At the SSPS amount of 3%, the leather is good in softness, as well as in physical and mechanical properties. Take-Away: 1.SSPS from soybean dregs is an acidic polysaccharide, which is rich in raw materials and low in cost. 2.Leathers filled with SSPS have good performance.

Content: Traditional leather industry involves mechanical, chemical and biological processes, and a lot of leather chemicals are widely used annually. In the beamhouse, especially in liming and re-liming, enormous pollution is usually released because of the traditional use of Na2S and lime. Many researchers have devoted to clean production for leather making. In this study, salt-enzyme liming process was studied in modern leather process to remove the inter-fibrillary matter. Three such salts as Na2SO4, NaCl, and MgCl2 were used with such enzymes as neutral protease and cellulase. The enzyme activity was evaluated by Folin Method. The opening up degree of collagen fiber bundles was observed by SEM and microscopic image of histological staining. The waste water was analyzed. The tannin absorptivity of the samples was evaluated by colorimetry. It was demonstrated that enzyme activity is not affected by salt, but it helps the action of enzymes on hides. Salt might accelerate the penetration of enzymes into the hide to promote the removal of inter-fibrillary and the opening up of collagen fiber bundles. The best fiber opening result was found by SEM at the MgCl2 content of more than 0.4 wt.% in liming. Microscopic observation by histological staining as well as waste water analysis indicated a good removing effect for the inter-fibrillary. This work may provide a cleaner leather making technology. Take-Away: 1.Salt-enzyme liming process was studied in modern leather process to remove the inter-fibrillary matter. 2.To provide theoretical guidance for the clean production of leather.