The Basle City Sky

​Basle is "the" Art City in Switzerland. The numerous museums of classical and contemporary art attract hundreds of thousands of visitors. It is also where the "Art" is staged every year, the biggest art fair in the world. Culture in general and the fine arts in particular have a long tradition at the Rhine bend. It is supported here equally by the public and by politics. So it's no wonder that a project was possible in Basle which would have had no chance anywhere else: The City Sky. The Christophe-Merian Trust, the Basle City Canton and a lottery fund support this art and culture project of the initiator and organizer Klaus Littmann. 

Objet d'art and sunshade 
Giant printed nets were hanging at different heights over several streets and squares of the Old City during the summer months. The material was a PVC-coated polyester fabric which is light and translucent yet still provides protection against the sun's rays. Various artists of international renown were enlisted to design the individual sectors. The result is an impressive total work of art which has temporarily changed Basle's countenance.

Successful teamwork 
The whole project from plotting (printing) the first stretch, the manufacture to the hanging up high above Basle's inner city took just one month. Close co-operation between various companies was crucial to keeping the deadline: MakroART did the digital printing, Carsa the fabrication and Famont the final joining and hanging of the nets on the building fronts. The nets processed with a welding machine from Leister the same day were suspended with polyester ropes to eyebolts at night. The assembly was performed between one and five in the morning when the overhead cables of the Basle city tramways were not carrying electricity.

Rational processing in demand 
The largest works of art measured 16 x 15 m. They were joined up out of five meter wide sections of different lengths. A total of approximately 5000 m2 of mesh fabric was printed, welded and mounted. To cope with the tensile forces of the polyester ropes, the edges were reinforced beforehand with a 48 mm wide PVC band. A material that is also used for manufacturing lorry tarpaulins. The Huby Meier company near Lucerne was contracted to prepare the fabric sections. The welding of the edging band and the fitting of the eyes and half-rings to the works of art was something very special even for this company who specializes in oversize advertising banners.

High demands on the tensile strength 
The band was welded on with a TAPEMAT from Leister. It is able to withstand a tensile force of 1,300 kg. The edge reinforcement by tape is easier and quicker than seaming. It meets the high requirements for stability and safety. An eye was fitted every 80 cm to be able to join the prepared sections later with cable ties. Half-rings were fitted to the long sides every 2.5 m to which the polyester ropes were fixed. The 1,000 half rings were first tacked with a manual HOT JET S from Leister and then sewn.

Fastest tape welding machine 
A total of 2,500 metres of PVC tape were processed. A TAPEMAT from Leister was purchased specially to rationalize the process. The new machine processes up to 20 m of tape per minute. That makes it the world's fastest tape welding machine.

Quality experience 
Basle always has a lot to offer. A visit this summer was even better. The City sky was a quality work of art which was well worth taking a look at. A walk through the covered Old City was an experience. Leister Process Technologies has made a small but valuable contribution with the use of its equipment.

Interview with Huby Meier, Managing Director of Carsa, Grosswangen, Schweiz. What is your experience with the TAPEMAT from Leister? 
It did the job excellently. We bought it in April specially for this work to be able to weld the tape rationally. Any other method would have been too slow. The TAPEMAT is very easy to handle. The welding parameters of speed, pressure and temperature can be optimally adapted to the different materials.

What convinced you most? 
It was incredibly fast. With a speed of up to 20 m/minute it is unbeatable. The quality is extremely high despite the processing speed. The tape can be joined easily at the suitable welding temperature even with the very light fabric used here.

Do you use other Leister machines? 
Yes, we have been using Leister handheld devices for years. We use the HOT JET S for fitting eye bands and welding details. It has become indispensable.

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Digital printing: MakroART, Grosswangen, Schweiz, www.makroart.ch
Fabrication: Huby Meier, Grosswangen, www.carsa.ch 
Assembly: Famont AG, Grosswangen 
Material: mesh Standard «seemee» von Verseidag 
Plastic welding units: Leister Process Technologies 
Text: Christophe von Arx, Leister Process Technologies 
Photos: Brigitte Bühler Barmett, Christophe von Arx