Commodities such as wet blue and pickled skin are often produced in the simplest, cheapest way. After the long transportation and storage times that are common, they need to be conditioned before further treatment. Proteases such as Hostazyme® AB NEW and Hostazyme® AD-6P have a mild hydrolyzing effect on the protein structure, thereby completing the bating and simultaneously restoring the properties of the freshly made material.
The benefits obtained at a particular tannery will depend on the process and on the type of leather produced.
Application of the proteases during acid conditioning offers the tanner one or more of the following benefits:
- Increased tear strength and tensile strength in finished leathers
- Improved area yield
- Improved absorption and distribution of chemicals
- Improved softness
Hostazyme® ADL and Hostazyme® AB NEW were applied to bovine wet blue. The wet blue was neutralized to pH 4-4.5. 0.3% Hostazyme® ADL and 1.5% Hostazyme AB NEW were added at 50°C at an interval of 10 minutes. After an additional 2 hours of drumming, the bath was drained and the wet blue washed once using 50°C water.
The wet blue was then finished up to shoe upper or upholstery leather. Observations on treated wet blue versus control:
- Enzyme-treated sides were brighter, cleaner, more let out and less wrinkled.
- Enzyme-treated sides were much more stretchy and much more pliable.
- Enzyme-treated sides showed a lot more area.
Observations on crust and finished:
- Enzyme-treated sides (shoe upper) showed significantly better tear strength (95% level).
Wet blue is a commodity that is shipped around the world. The material is often produced in the simplest way, which means that it can lack quality. The long transportation times may also cause it to dry out and become creased (folded). Before further processing, soaking/ conditioning is often necessary. If the preference is to do this during neutralization, Hostazyme® AB NEW is recommended for the purpose, optionally combined with a lipase due to the synergistic effect of the two types of enzyme.
Hostazyme® AB NEW is mainly used in the following processes: 1) As a complementary enzyme during pickled skin and hide de- greasing, 2) Acid (pH 3.5-4.5) conditioning/ wetback of wet blue
Degreasing of pickled skin usually involves either dry cleaning or a high usage of surfactants such as NPE.
These chemicals are being phased out of the leather processing industry and alternatives are being sought. So Hostazyme® AB NEW in combination with Hostazyme® ADL is a serious candidate.
This application produces significant amounts of FFA. At low pH, the FFAs are insoluble and it is recommended combining the enzyme treatment with a pre- tannage.
- Hostazyme AB New
- Hostazyme AD-6P