FAQs - GSC Group


The 3 key points of OMW are CIRCULAR ECONOMY, FLEXIBILITY and PERFORMANCE. OMW technology combines natural, reusable and sustainable waste water from the olive oil industry with specially designed polymers to give the commercial chemical named as SUSTAN FP. OMW technology leads to a variety of leather articles, meaning it can be suitable for different applications, such as automotive, footwear, garments etc. OMW technology gives consistent and efficient results towards the manufacture of leather.

OMW technology can be used both in the tanning and retanning steps, leading to a fully OMW product. Its applications are highly flexible and intertwined with benchmark processes: it is suitable for the retannage of mineral tanned hides (such as chromium tanned hides); it could also be used for wet-white retannage. Tanned OMW hides could be processed according to standard procedures.

OMW application is compatible with vegetable tanned leather: they both rely on natural components as the tanning agents, and therefore they find a positive synergy which is then exploited in the tanning applications.

Since OMW technology exploits the utilisation and revaluation of the olive mill waste water, our technicians have developed specially designed procedures based on the same approach. The utilisation and contribution of raw materials from agriculture in the OMW product range is highly remarkable, which ultimately provides renewable carbon sources along with less impacting products. Overall, the OMW product range impart higher bio-based content to the leather than standard products, especially focusing on the retannage.

The OMW product portfolio is mainly based on SUSTAN FP and SUSTAN PRE; also including designed fatliquors, resins and synthetic tannins. The OMW product range is mainly based on natural raw materials and the remarkable contribution of bio-based carbon.

OMW technology belongs to metal-free tanning processes; it can be included within the alternative technologies that can serve the future of the leather industry. Waste generation leads to solid and liquid wastes, the former including leather shavings and leather scraps. Liquid waste include the tanning liquor, the retannage liquor and the sludge generated from both parts. At present, the solid waste is included in CER040199, whilst the liquid waste refers to CER040105 and CER040107 for liquid waste-water and sludge respectively. The reutilisation and the revaluation of the leather shavings is one of the main topics of GSC Group R&D: since OMW is a fully organic chemistry based tanning technology, no heavy metals or harmful substances can be found in the solid waste, meaning the possibility of a complete recovery via thermal treatment of such substrate. The liquid waste-water is free from heavy-metals and can be treated following standardised waste-water protocols, although it is found to be higher in the organic load than chromium technology. The sludge is also free-from metals and harmful contaminants, and is entirely composed of organic compounds. This means the sludge can be addressed to further physical and chemical treatments instead of landfill disposal.

OMW chemicals are formaldehyde-free; however, traces/residues of unreacted dialdehydes can be found in SUSTAN PRE, although their concentration is far below safety concern and do not affect its CLP.

The mechanism of action of OMW technology relies on the synergy between natural polyphenolic species from olive industry and synthetic tannins. OMW is a complex and variable material, rich in polyphenolic species such as hydroxytyrosol, tyrosol, catechol etc and some organic acids such as gallic and caffeic acids which provide part of the tanning effect.

The combination of both SUSTAN PRE and SUSTAN FP is unique and peculiar, bringing the tannin effect to the leather. SUSTAN FP can be considered as a polymer with phenolic tanning properties, although it has tanning properties when used in very high concentration.

OMW enters GSC facilities as a raw material, which requires a series of specifications to be met prior its utilisation. OMW must be characterised in terms of solids content, viscosity, acidity and tanning properties. OMW polyphenolic content is key point for the correct exploitation of this raw material: polyphenols interact with the hides via micro-interactions which contribute to the leather tannage; thus, in order to have consistent performances, their concentration must be in line with some specific range defined by GSC R&D and technicians. After the initial controls, the workflow foresees the OMW concentration and stabilisation via a series of physical and chemical actions respectively. Finally, OMW are retested for the polyphenolic content via titration to give a consistent and reproducible raw material.

GSC Group guarantees its product for 1 year from the shipment; the products must be stored properly at the warehouse to prevent undesired loss of performances. We strongly recommend to stir well before using the SUSTAN FP.

We believe it is the best eco-friendly metal free technology available in the market to achieve any type of leather.