The Rupp Report: A Pioneer Has Passed Away

Not many people have influenced the finishing industry in general, and particularly the dyeing
industry in such a tremendous way as Wilhelm Christ did. This is a tribute to a great engineer, but
even more to an extraordinary personality, with whom the author was fortunate to spend a few years
of his working life. Some days ago, this true gentleman closed his eyes to start his last trail at
the age of 88.

A Funny Idea

For centuries, large quantities of water, which is a precious human resource, have been used
for the dyeing of textiles. Against this background, the development department at Then Maschinen
GmbH set itself the task of reducing both the enormous volumes of water needed for piece dyeing and
the related energy costs. The dyeing and finishing industry has been challenged to find more
economical and environmentally sound methods for a long time. In this field, Wilhelm Christ is a
recognized pioneer.

Rethinking began in 1979, when Then developed the Airflow® technology. Up to this point in
time, increasingly expensive water served as the transport medium. In the 1970s, a winch-dyeing
machine required a massive volume of around 150 liters for the dyeing of 1kilogram of fabric. In
addition, this water had to be heated. It was in view of these statistics that Christ, the head of
Then’s R&D department, tackled the question of how the enormous water consumption needed for
piece dyeing could be cut along with the accompanying energy costs.

This was impossible with traditional machines, as they employed a bath; and even with a jet,
water remained the transport medium and, therefore, consumption was high. In 1979, work started on
the development of Airflow technology in cooperation with Hoechst AG, Germany. The starting point
was the so-called Rapidcolor process for isothermal dyeing. This process was used primarily for
yarns in a creel system, and Christ upgraded the system, which meant that following heating in a
steam flow, the separately heated treatment bath was conducted into the jet nozzle for fabric
transport and was thus kept in circulation.

The Initial Success — The Patent

The next task was to distribute the reduced quantities of dyestuff and additives across the
fabric evenly, which could only be achieved by an aerosol. The aerosol replaced the treatment bath
and resulted in a completely changed mass ratio. Now, the development proceeded in giant steps, and
the basic Airflow patent was registered in 1981. Inventors were Wilhelm Christ, from Michelsbach,
Germany; Dr. Hans Ulrich von der Eltz, from Frankfurt; and Albert Reuther from Frankfurt.

The European patent was registered in 1982, and the use of the technology commenced
simultaneously in numerous countries around the world. A U.S. patent was granted in 1984. The new
dyeing machine made its public debut at ITMA 1983 in Milan and was met with general ridicule from
the world’s experts. “This machine received skeptical smiles from the world experts. However, then,
the first prototype machine of 10 kilo load size was installed at the application laboratory of
Hoechst AG. Subsequently, Then successfully commercially introduced the technology,” Christ once

The first autoclave-design Airflow machine made its debut at ITMA 1991 in Hannover, Germany,
and possessed the basic features of the current machine. The most important characteristics of the
technology were time savings; cost efficiency, reliable dyeing, material protection and reduced
ecological impact.

It’s The Air

The replacement of the dyebath by an airflow as the transport medium for piece goods in
jet-dyeing machines is a patented, pioneering achievement from Wilhelm Christ and his team at Then.
The moisture-saturated airflow furnishes uniform temperature distribution across the fabric and in
the machine, which is a prerequisite for even and reproducible dyeing. As a result of the low
liquor content in the dyeing autoclave, the goods are lighter than in a conventional machine and
can therefore be more quickly accelerated to high speeds. The risks of draft or yarn strain are
minimal, which is of special advantage with regard to the finishing of articles containing

The Long Trail

And now it’s over. Fong’s Europe GmbH, the former Then Machinery GmbH, has reported that
Wilhelm Christ has passed away at the age of 88. For more than 30 years, Mr. Christ was the
mastermind behind the company’s research and development. More than 30 patents related to the Then
products are noted and credited worldwide to him.

He was truly the father of the Airflow technology, which, by no doubt, still today sets the
standard for water savings during the dyeing process. As a result of his fruitful work, he received
many awards, including the American Association of Textile Chemists and Colorists’ (AATCC’s) Henry
E. Millson Award for Invention, and he has been one of only a few Europeans up to now to be given
that award.

Fong’s Europe wrote: “Having lost a great colleague, visionary and friend we are sure that
his spirit will remain in our company and in many dyehouses worldwide.” The condolences of the Rupp
Report and all its colleagues goes to the family of a great inventor, a true gentleman and a
friend; and to all the people who had the privilege to work with him.

April 23, 2013