February 2, 2000

Luxury leather - the natural way
Rhubarb used to tan leather

As natural as possible: this is the motto for a new type of leather that Audi is currently testing for use in its vehicles. In order to achieve this objective, a substance is used in both tanning and dyeing which is obtained from the root of an indigenous type of rhubarb. This is a sustainable natural product that does not create any pollutive waste in production. Nor does it have to be imported from far away like other naturally extracted tanning substances. The broadcasting company Mitteldeutsche Rundfunk has just presented this initiative with its 1999 Innovation Award.

Sensitive noses are quick to smell that the new leather is produced naturally. Its aroma, which is not masked by a hint of anything artificial, is combined with subtle shades of ochre to create a genuinely high-quality atmosphere. It is not least for this reason that rhubarb leather is initially to be used to give the luxurious ambience of the A8 a unique, additional quality.

Sustainable raw materials are also playing an increasingly important role for Audi in other areas of car manufacturing. Jute, hemp, flax and sisal provide fibres that can be used for door trims, for example. The same strict quality standards apply to natural products as to synthetically produced materials.

Bothersome odours, for example, are absolutely taboo and exclude a product from being used in cars. This is one reason why Audi has already had the cultivation of natural products closely examined.

The Agricultural College in Bernburg/Thuringia had cultivated two hectares of land for growing rhubarb. The first harvest in October 1999 yielded sufficient tanning agent for preserving around 8000 square metres of leather. The company Wertleder from Zug in Saxony, which has already proved to be a reliable partner in the past, is responsible for the production of leather on behalf of Audi.

The new material for vehicle seats and interior trims now has to get through extensive endurance tests. In the vehicle it is exposed to extremely diverse climatic conditions and has to withstand the effects of light and air humidity. Even the strain on the leather caused by the weight of the driver throughout a long car life is simulated on the test rig.

The particularly environmentally friendly production of leather is nothing new for Audi. Chromium salts, which were the most important tanning agent in the leather industry for around 100 years, have been banned from its production since 1990. As part of the preservation process, chromium salts turn animal hides into very soft, easily manageable leather. But their use produces around 175,000 tons of heavy-metal residue annually in Germany alone.

This prompted Audi almost a decade ago to stop using leather in its vehicles which produces such substances during its manufacture. The company's leather suppliers have undertaken to use only heavy metal-free processes which are more ecologically acceptable. Both synthetic substances and vegetable extracts - currently obtained primarily from fruits, leaves and tree bark - are used as tanning agents.

The product obtained from rhubarb root cannot replace these substances in volume production, at least not at the moment. A maximum of three percent of the tanning agent required can be extracted from the root. But the demand from Audi customers for leather which is manufactured as naturally as possible is growing. And it is already clear that the area for cultivating rhubarb can be extended without any trouble to meet increasing demand. These are good prerequisites for a new and important chapter in the field of environmental protection in the automotive industry.






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