 The chemical reactivity control of collagen: The Hofmeister Effect rev... [premium content]
The Hofmeister effect concept was noted over a century ago. This concerns the action
of certain ions in the solubility character of some colloids due to the partial
breaking-up of the internal helical structure. Stabilising salt-linkages between charged
protein side-groupings are broken, which in turn makes more charged groups available.
In the case of collagen, these effects can be employed to gain improved reactions with
tannage-related chemicals.
World Leather - 03 - May 2008
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Companies act to keep chromium VI out [premium content]
The problem of chromium VI does not appear to go away, and is being taken very seriously by fashion groups, especially those selling children's footwear. Some of the issues raised – such as Cr(VI) being 5% above a limit of 3 ppm as determined by one laboratory (+0.15 mg/l) with three other laboratories suggesting the level was acceptable – are playing with determinations on the fringe of detection. However, when health matters – and especially children's health – are considerations, any concerns of the consumer will be driven by
what is perceived as opposed to any technical debate.
World Leather - 08 - Dec/Jan 2008
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The scientific and commercial significance of variations in strength a... [premium content]
Any variations in physical properties—especially the degree of stretch under load and the tensile strength—need to be accommodated within a manufactured item to both extract the best value from the leather and, in the longer term, to ensure customer satisfaction. This applies to almost all items manufactured from leather—garments, leather goods, furniture, automotive components, and footwear—as there is a need for shape retention during wear and use.
World Leather - 07 - Nov 2007
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The theory and practice of direct pickle/chrome liquor recycling [premium content]
Minimising the chloride/sulfate and chromium ion content from pickle tanning
Although the information set down in this paper is fundamental to the highly successful technology and this is probably the most informative study that has been written on this subject, it should be remembered that the original report was produced before the technology became widely established and some minor details will have changed by now.
World Leather - 06 - Oct 2007
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The determination of chromium (VI): Standardisation status [premium content]
The co-existence of two different procedures for determining hexavalent chromium in leather across Europe has placed this hazardous substance once more in the midst of controversy.
World Leather - 06 - Oct 2007
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Collagen as a substrate for biomaterials: Part 1 [premium content]
Using advanced biotechnology, it is possible to cut specific regions of the collagen molecule in order to solubilise collagen whilst, at the same time, retaining its helical nature. This new form of collagen can then be precipitated from solution, solubilised and moulded into any shape or form that may be required.
World Leather - 05 - Aug/Sept 2007
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The application of modern biotechnology methods and the manufacture of... [premium content]
The increased use of biotechnology methods by leading chemical supply companies is impacting the way that leather is produced today. Changes have resulted in improvements to the repeatability of processing, reductions in cost, and a decrease in the environmental footprint along with improvements in leather quality.
World Leather - 05 - Aug/Sept 2007
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Formaldehyde analysis: Test methods and results [premium content]
There have been recent changes in the understanding of the toxicity of formaldehyde, and a proposed change in the testing method. With the realisation that the greatest risk to human health comes from airborne formaldehyde, test methods are now tending to change to reflect this.
World Leather - 03 - May 2007
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Chrome tanning process without a float and with low salt content [premium content]
The convential chrome tanning process results in significant pollution of wastewaters. To reduce these effects an investigation has been undertaken that involved a pickle without a float and the minimum level of salt required.
World Leather - 02 - April 2007
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Neutralisation: the key to successful retannage, dyeing and fatliquori... [premium content]
The main purpose of the neutralisation process in the
production of chrome-tanned leathers is to reduce the
acidity throughout the hide or skin structure. This is to
enable the retanning, dyeing and fatliquoring processes to be carried out successfully. In chrome leathers, pH values usually range from 3.0 to 4.0, and this is far too acidic to allow penetration of anionic products. Neutralisation increases the leather pH to levels that are generally between pH 4.2 and 6.5.
These values depend upon the type of leather being produced,
and it is only rarely that higher pH values are employed.
World Leather - Oct 2006
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