Content: The toxicity and unpleasant smell of hydrogen sulphide (H2S) gas is an issue for the leather industry that has been contained rather than eliminated in tannery practice. Completely eliminating H2S from tanneries while maintaining practical and economically feasible processing is still a big challenge to be addressed. Significant progress has, though, been made by introducing robust and reliable low sulphide unhairing systems based on selective soaking and specific enzymatic liming auxiliaries. These systems allow the reduction of sodium sulphide offers from the typical 2.5% to 1% of pelt weight. These lower levels reduce the amount of hydrogen sulphide gas released into the environment from the liming float, as well as the amount of sulphide that is carried over in the hide to subsequent processing steps. Overall, the H2S problem is not eliminated, but significantly reduced with this technology. In a further evolution of the technology, organic thio compounds can be used to fully or partially replace the already low levels of sulphide required, and thus allow to operate with offers well below 1%, or even completely without inorganic sulphide. Due to their reductive power, the organic thio compounds react with keratin in a similar way as inorganic sulphides, but they are oxidized much faster, which is advantageous for the effluent load. Alternatively to, or in combination with organic thio compounds, H2S scavengers can be used to reduce or eliminate hyrogen sulphide released from liming floats. Different types of scavengers are available, but the selection is limited for technical and economic reasons. The paper on hand shows how the release of hydrogen sulphide from beamhouse operations can be effectively controlled by a combination of technologies involving more effective unhairing with lower amounts of reductive agents, replacement of inorganic sulphide by organic thio compound and the use of H2S scavengers. Take-Away: - The release of toxic H2S from Beamhouse operations can be effectively controlled using modern unhairing technologies allowing to use no or low sulphide. - These modern unhairing systems are based on a combination of selective soaking, unhairing assisted by enzymes with specific activity and the use of organic thio compounds.

Content: A characteristic of leather is that if it is gradually heated in aqueous solution it reaches a temperature where sudden and irreversible shrinkage occurs. This phenomenon is related to the denaturalization of the collagen protein that conforms the hide and is known as leather shrinkage. Specifically, the internal bonds break thus causing a shortening of the skin that can be up to a 35% from its original length. Accordingly, one of the most used methods to check the quality of the leather tanning process is the determination of the contraction temperature according to the ISO 3380:2015 standard. This method measures the leather shrinkage when constantly increasing the sample temperature. The shrinkage temperature corresponds to the temperature when the sample suddenly contracts. The value of this temperature indicates the degree of collagen stability and therefore, when higher, the leather will have better quality and resistance. The process of leather shrinkage can be divided in different stages. Several authors discriminate temperature A1 (when the first fibre starts to shrinkage), temperature C (when there is a massive shrinkage) and finally temperature A2 (when the last fibres are contracted individually). The method that describes the ISO 3380:2015 standard uses a device where the determination of the shrinkage temperature is performed visually by the laboratory technician. Consequently, the method tends to be imprecise and subjective. It should also be noticed that the device proposed by the standard does not allow differentiation between the different stages of the contraction process. There are other methods to determine leather shrinkage temperature including differential scanning calorimetry, microscopic hot table, thermogravimetric analysis, differential thermal analysis and thermomechanical analysis. All these methods involve complex devices and are only suitable for specialized personnel. In this work, a new device is developed to precisely measure the leather shrinkage temperature and to distinguish the different contraction stages. In addition, the proposed device is simple, easy to use and inexpensive, which facilitates its use in any industry. The developed system consists basically of a load cell to measure the strength produced by the shrinkage of the leather. With the logged data during the test a strength versus temperature graph is built. By means of its interpretation, the different stages of shrinkage can be determined. Different mathematical analysis of the logged data is proposed to determine the shrinkage stages temperatures, thus achieving a high degree of certainty and repeatability. Take-Away: A new device, simple and inexpensive, is developed to precisely measure the leather shrinkage temperature and to distinguish the different contraction stages.

Lignosulfonates are abundantly available by-products of the paper industry. In the vast majority of applications on leather lignosulfonates are physically blended with other chemistries to augment filling properties of the resulting products. We targeted to decrease the molecular weight of lignosulfonates using fungi to achieve increased application possibilities and to improve tanning properties. We screened various basidiomycotes for their capability to modify the molecular weight of calcium lignosulfonates and identified five species that actually polymerized the chosen lignosulfonate further. Only Irpex consors was found to depolymerize calcium lignosulfonate in surface and later in liquid cultures in our hands. We achieved a six fold reduction of the molecular weight determined by size exclusion chromatography.

Content: Leather manufacturing is classified as water, energy and waste intensive by the Industrial Emissions Directive (2010/75/EU). Tannery effluents, if not properly treated, cause significant damage to soil and water bodies. Over 85% of world leather production involves the traditional chrome tanning process (TCTP). The use of chrome (Cr) in the industrial processing of animal hides poses serious environmental and health problems due to the use of hazardous chemicals, the production of solid/liquid waste and air emissions. LIFE GOAST aims at demonstrating the benefits of a new tanning technology on a semi-industrial scale; the project started on July 2017 and is an ongoing investigation, and involves the competences of three direct actors in the leather industry such as GSC Group spa as chemical supplier, Conceria Pasubio as tannery and Mediochiampo as waste-water treatment agency, in conjunction with the expertise of Università di Venezia, thus forming together a model of leather industry. The technical feasibility of LIFE GOAST implementation, as well as its social and economic impact, have been monitored and compared with the TCTP in order to demonstrate the reduced environmental impacts of the new process, while producing comparable or better quality leather. The LIFE GOAST team demonstrated that it was possible to treat collagen with the GOAST technology to give stabilised collagen to be used in the leather industry. A series of leather swatches were realised in accordance with the new protocol in order to obtain preliminary information on chemical oxygen demand COD of the effluents and technical feasibility of the process. The results were remarkable: COD values were lower than TCTP and it was possible to obtain soft and firm grain leather despite a shrinkage temperature lower than chromium process. However, these preliminary results allowed to process bigger pieces of leather (quarter, half and entire) to demonstrate that the technology was reproducible and in line with the small trials. The investigation is still ongoing and the team is fully committed to focus on the objectives of the project. Take-Away: Novel and alternative tanning systems to traditional chrome tanning.

Content: Consumers perceive leather as a durable and natural product. To support this positive image, car manufacturers have set demanding performance profiles addressing wear, emissions and sustainable manufacture. Poor performance of auto leather becomes visible as the polymeric finishing coat wears off or cracks over time. Therefore ageing property is seen as a representative key performance parameter and is determined by checking how flexible and strong a polymer coating remains after leather has been exposed to light, heat and humidity for a given time. Ageing of leather is complex to determine and depends on various parameters and requires a full system approach . In a first step different type of crusts (wet-blue, wet-white) were prepared and finished with a standard polyurethane coating. It turned out that the selection of the right fat liquors and tanning agents as well as the presence of vegetable tannins play an important role. On top of this the effective use of proper protective chemicals like anti-oxidants is needed. In a second approach the polymer coating itself was studied and optimized with regard to aged flexing and abrasion. Parameters like polymer type, crosslinking, application technology, coating thickness and impact of additives were investigated and tested when applied on the best crust leathers selected from part 1 of this work. Results show that not only is the right selection of polymers critical but also so is the way the coat is being applied . Furthermore coating thickness greatly defines wear (abrasion), lightfastness and ageing properties. Additives like dulling agents, levelers, feel agents, waxes ,fillers although needed can weaken the integrity of the polymer matrix and consequently reduce physical and chemical fastness properties. This may also apply to a certain extent to protective additives such as anti-oxidants and UV stabilizers, but when used properly their advantages outweigh the potential disadvantages. As to application, special emphasis is given to transfer coating technology which can provide advantages in application and quality consistency but also with regards to fastness properties such as wear and ageing. Take-Away: - crust leather has a critical impact on performance of finishing coat of automotive leathers and requires careful selction of products and use of protective chemical - polymer selection and use of protective chemical play an important role for achieving good aged flexing performance - type of application of finishing coat on auto leather further determines the performance of coating

Content: Developing novel tanning agents from renewable biomass is regarded as an effective strategy for sustainable leather industry. In this study, a series of dialdehyde carboxymethyl cellulose (DCMC) were prepared by periodate oxidation of carboxymethyl cellulose (CMC) with varying degrees of substitution (DS: 0.7, 0.9 and 1.2). The structural properties of DCMC were characterized. Size Exclusive Chromatography measurements showed that CMC underwent severe degradation during periodate oxidation, resulting in the decline of weight-average molecular weight from 250,000 g/mol to around 13,000 g/mol. FT-IR analysis illustrated that aldehyde group was successfully introduced into DCMC. The aldehyde group content of DCMC decreased from 8.38 mmol/g to 2.95 mmol/g as the DS rose from 0.7 to 1.2. Interestingly, formaldehyde was found to be produced in DCMC, and its content was 159.4, 151.7 and 38.4 mg/L, respectively when the DS of CMC was 0.7, 0.9 and 1.2, respectively. Further analysis by HPLC found that fructose was formed during oxidative degradation, and was subsequently oxidized to generate formaldehyde. This was in accordance with the fact that higher DS resulted in lower formaldehyde content in DCMC. The whole reaction mechanism is still under investigation at the moment. Tanning trials showed that the shrinkage temperature and thickening rate of DCMC tanned leather decreased as the DS increased. This should be due to the difference in aldehyde content of DCMC. Leather tanned by DCMC-0.7 (DS of CMC was 0.7) had the highest shrinkage temperature of 81°C and thickening rate of 76%. It was noteworthy that the formaldehyde content in DCMC tanned leather was only 0.11-0.40 mg/kg even though DCMC contained a small amount of formaldehyde. In general, we hope the work on dialdehyde tanning agent derived from CMC could provide some essential data for the development of sustainable tanning material and process. Take-Away: 1. Higher degree of substitution (DS) of CMC resulted in lower aldehyde group content of DCMC. 2. The formaldehyde content of DCMC was negatively correlated with DS. 3. The tanning performance of DCMC with lower DS was better.

Content: Fine hair is the biggest seasonal challenge for bovine leather production in the United States. The origin, timing and severity of the fine hair problem can be unpredictable and vary from year to year. Seasonal changes on the hair growth cycle are prompted by the lower temperature from fall to winter; the cow hair increases in amount, length and thickness. This problem is very old and has increased in intensity due to changes in the leather manufacturing process, cattle breeding conditions and breed diversity. The amount of fat and thickness of the hide also play important roles. The extent of the problem has not been documented and is not fully understood by the scientific community. The presence of fine hair (residual hair) on the wet blue and final leather are a cause of downgrading the leather. If the wet blue has fine hair, it cannot be removed in further processing in crust or finishing. Some leather types can tolerate more fine hair than others. In this paper we will conduct a scientific evaluation of the fine hair on American bovine hides, wet blue and finished leathers through cross sections and stains, optical and electron microscope observations. We will include measurements of hair thickness and hair depth inside the hide. The work will compare sulfide and oxidative unhairing of winter hides, characterize and show the details of the fine hair through cross sections, and offer indicative measures to minimize the problem. Information from the largest wet blue manufacturer in the US with four tanneries will provide insight on the fine hair seasonality, types of breeds and cattle displacement temperature ranges and will discuss adaptive changes needed in the “Winter” time to control the fine hair. Take-Away: 1) scientific review and evaluation of the problem of fine hair though cross sections and stains, optical and electron microscopy observations 2) evaluate the fine hair on sulfide and oxidative unhairing; providing indicative measures to minimize the problem 3) characterize the seasonality of the fine hair problem regarding the types of breeds, displacement temperature ranges and adaptative changes to control the fine hair

Content: In order to contribute to a more sustainable leather manufacturing process and leather value chain, in 2016 Smit & zoon started its own designing process of new products through the Bio-Based innovation platform. As a logical first step, answers to several key questions have been looked for: What is Bio-Based? What is renewable? Which term and method do we use to define the Bio-Based content in the Bio-Based platform? What is biodegradable? How do our current products perform? What is our vision for future products? In the process of answering these questions and guided by the Cradle-to-Cradle (C2C) CertifiedTM program, Material Reutilization Score (MRS) was used to obtain deeper insights into the formulation and environmental performance of our leather chemicals and treated as the basis for the design of new generation bio-based chemicals. Three main focus areas are setting the tone of current activities in the Bio-based platform: 1. increasing the renewable contents of the existing product groups; 2. smart valorization of industrial side streams from biological origin and 3. improving the biodegradability of leather chemicals. While focusing on these topics, it is well-understood that a proper balance needs to be found between cost, sustainability and performance. In the meantime, leather’s end of life scenario plays a role and needs to be looked at again. One of the first results of this focused approach is our patentpending polyphenolic syntan product, in which industrial lignins are used during the chemical conversion process to replace part of the phenol (40-50 w/w%) used in the production of otherwise 100% petro-based polyphenolic retanning chemicals. We have shown that our innovative technology is compatible with most of the industrial lignins (kraft, soda, organosolv, hydrolysis) from different origins (soft/hard wood, grass, straw). The obtained polyphenolic products have real tanning power and are suitable to be used as retanning agents for various types of leather rendering good organoleptic properties with additional added value of increased bio-based content, improved biodegradability thus a higher MRS. The improved biodegradability of these products can contribute to decrease the effluent treatment load. Moreover, these products can be tailor-made to meet low emission (low free phenol, low free formaldehyde) requirements as well. In addition to the lignin-based polymers, the quickly developing project portfolio within the biobased platform manifests that Smit & zoon is making steady steps towards a largely sustainable leather value chain by 2025. Take-Away: Bio-Based products contritbute to a sustainable leather manufacturing process and leather value chain. Both the raw material renewability and product biodegradability are important parameters to evaluate the environmental impact of leather chemicals. Smit & zoon has developed a patent-pending bio-based synthan product using industrial lignins to replace part of the petro-based phenols in the production process.

Content: Car industry is highly demanding for low emission parameters and despite remarkable results have been achieved since the last decade, the requests are day by day more sophisticated. The focus on emission is a severe task and requires the investigation on emissions on full-range and involves the expertise of multi and inter disciplinal competences. The leather industry is a clear key ring for car interior suppliers and it is also focusing on more sustainable processes and reducing the emission of pollutants to the environment, prompting the commitment of leather suppliers, tanneries, and chemical auxiliaries producers. From our perspective, in fact, one of the major problems that car interior producers are currently facing is the production of low-emitting leather, which requires special chemical auxiliaries to be achieved. In this context, our research has focused on the study of VOC volatile substances from car interiors, in particular on finishing systems, aiming at their reduction without losing the original performances of the finished leather article. Our investigation focused on full grain finished leathers, evaluating the contribution to the VOC emission from crust leather to the finished articles. A preliminary study showed that silicon compounds family brought an important contribution to the emission from a qualitative and quantitative perspective: these substances play a crucial role in terms of the final article performances (such as resistance), and quality. So, our investigation focused on innovative silicon-free auxiliary combination to give low VOC emission contribution from the leather compared with the same performances of the original silicon containing finishing. In order to evaluate the impact of the emissions, a series of analyses of the volatiles were performed: static headspace VDA 277 (and/or PV3341) analysis and active air sampling analysis GS 97014-3 type were performed, indicating that silicon contribution was very high in the emission. In addition, the quality of the leather was also assessed and characterised through standard automotive tests such as stick-slip, abrasion trials with Taber tester and Martindale machine, ball plate method, fogging test; rub fastness provided with Veslic tester (wet, dry, alcohol, gasoline), dry-rubbing trial with Gakushin tester. The set of result showed that standard leather containg silicon compounds on the finishing produced high VOC emission and high performance articles, thus contributing to VOC emission. Conversely, the novel finishing auxiliaries had low VOC emission, no silicons, yet high performance leather and therefore should be chosen from a more environmental point of view. Take-Away: Low VOC emission from novel leather finishing albeit high resistance leather.

Content: Providing peculiar enhanced features to leather items is a factor of primary importance for the marketing of high-end articles; although the tanning production is oriented to satisfy a wide market range, it is mainly in the 'high end' and 'premium luxury' categories that the quality properties of the material are more expressed, indeed, and where the main current challenges have been focalized, in terms of technological innovation, sustainability and product quality. The light-coloured leathers belongs to the category of materials designed especially for the luxury market. For this type of articles, the uniformity of the colour and the agreeableness of the overall surface appearance are crucial requirements for the most of international fashion and luxury brands. One of the most common and undesirable defects of this type of article is the alteration of the color, with particular reference to the effects of yellowing of the surface of the material. There are several causes able to contribute to this type of defects, due to the complexity of the matrix and to the variability of traditional or innovative production processes used: from the fragility, photosensitivity and thermo-sensitivity of the finishing polymers, to the chemical instability of some finishing pigments, further than the presence of photosensitive additives, the migration of skin components or assembly components of the articles (fats, fillers, plasticizers, glues, etc.), up to the indirect contribution of environmental and thermo-climatic factors able to affect negatively the performance of the material. SSIP, which has always been involved in research and consulting activities for the leather industry with regards to defect monitoring, through this work, would offer an overview of all the main tools for advanced diagnostics (with particular reference to Scanning Electronic Microscopy and to chromatographic and spectroscopic methods) aimed to the identification of the causes of yellowing, beside to explore innovative solutions for the development of strategies for the resolution and / or minimization of the problem of yellowing. The technical solutions will include innovative tanning processes, innovative finishing methods, and leather surface treatments carried out in order to provide a sensible attenuation of surface absorption of IR (infrared) and UV (ultraviolet)-visible radiation. Take-Away: Advanced Diagnostics and innovative solutions for leather yellowing