An annual meeting of technical representatives from Member tanners and fellmongers is held at LASRA to steer all research projects for the following year, including agency-funded research. Results from the previous year’s work are reported on and discussed, and suggestions for follow-up work or new projects are proposed. A second meeting is held later in the year prior to the Conference to provide a running update on progress.
A rating scheme is used to prioritise the projects, ensuring only relevant research is conducted as a priority.
BET surface analysis of loose and tight hide using porosity
Understanding the differences in the structure of loose and tight cattle hide at different hierarchical levels provides useful information for developing improved processes. In this work, samples of crust leather identified by break analysis as being either loose (break scale >6), or tight (break scale <3) were analysed using an automated surface area and pore size analyser (Micrometrics, GEMINI V) with BET surface area and pore size distribution results for the different groups.
Early detection of looseness in bovine hides using ultrasonic imaging
Hides from looseness-prone and control cattle were selected in the beamhouse and processed to crust, with ultrasound measurements being taken at three process stages. The differences between loose and tight hide at these three stages was clearly shown in threshold images, showing promise for the development of an in-line ultrasonic measurement of looseness in the tannery.
Pickled Hide Wet-blue Hide Crust leather
B-scan images of pairs of tight (LH image) and loose (RH image)hide at pickle, wet-blue and crust stages. Red colour is indicative of low density
Characterisation of loose cattle hide using rheometry
Whilst rheometry is most commonly applied to the investigation of fluids and gels, access to a high precision rheometer at the Riddet Institute allowed us to investigate the fluid properties of a leather substrate. Our particular interest being any differences between loose and control cattle hide at the crust stage. Elastic and plastic behaviour on both were easily measured using this instrument, with lower elastic modulus measured for looser crust. Further work is planned for deerskin crust and wet-blue hide.
Using FTIR to diagnose heat damage
FTIR analysis was applied to pickled cattle hide which had been heat damaged. Analysis was able to identify differences, which makes diagnosis of this type of damage much simpler, but was unable to differentiate between heat damage from hot water immersion and heat damage from concentrated acid. Three peaks on the scans were specifically identified as points of difference. With FTIR being such a simple and rapid method of analysis, we will be applying this diagnostic technique as a first step in investigations of suspected heat damage in the future.
Benchmark figures for pickled pelt analysis
A study to determine the ratios for soluble to total protein and calcium sulphate to total protein; free acid, free salt, pH, shrinkage temperature and iron levels in industry supplied pickled pelts highlighted those plants meeting the current LASRA guidelines. A review of the guidelines is underway, but many have been found to still be relevant and necessary.
Testing of APEO alternatives
APEO degreasing agents have been available for a number of years for degreasing pickled pelts, but performance is often variable compared with NPEO. Two alternative linear alkyl ethoxylates were compared with a NPEO of known performance, and grease analysis carried out at the wet-blue stage. Crust levelness and physical strength were found to be comparable or superior to the classic NPEO, and in one case, grease levels were achieved which were lower than the control.
Biochar – chrome retention
A potential issue in regard to generation of biochar for tannery waste is the oxidation status of any chromium present in the biochar and its potential to be leached from the biochar product into the environment. An experiment was carried out to investigate the oxidation state and extractability of chrome from biochar generated from chrome containing leather waste. This study showed that higher temperatures prevented leaching of chrome from the biochar and that under no conditions was hexavalent chrome generated, the chromium being locked-up in a stable carbide compound at higher temperatures.
Thermogravimetric analysis (TGA) of fire-proof leathers
The thermal properties of flame retardant treated leathers were compared with conventional leathers, based on mass, temperature and time. Analysis of a LASRA-developed fire-proof leather, which uses a REACH-compliant active ingredient, showed it lost up to 10% less mass at any given temperature in comparison with the control leather. This technique has been applied to the QA of flame retardant leathers