[Making Of c--c]

swipe or use arrow keys or click left and right page margins to navigate between pages

Digital rendering are great. At trade fairs however, exhibits on 1:1 scale, for visitors to touch are required. Hence in autumn 2014 we were in pretty urgent need for 1:1 prototypes of the c--c channel glass concept.

Countless suppliers were asked for a quote: Industrial glass manufacturers, glassworks as well as individual artists. None of them was willing to place a bid.

The parts in question: normal flat glass 6mm. Their purpose is described here.

Eventually, we decided to create these elements on our own. Admittedly without ever having worked with warm glass before... The following pages document the process. Disclaimer: This artisanal process differs greatly from methods one would choose to create these shapes at industrial scale.

Animation-traditional-gravity based-Glass-bending

Usually flat glass is bent with simple convex or concave moulds. A sheet of glass is heated together with the mould using a special kiln. As the glass gets ductile it gradually takes the shape of the template.

In our case this particular approach didn’t seem exactly promising...

animation-of-alternative-glass-bending-options

therefore a great variety of alternative bending methods were considered.

Finally we came up with this kinetic bending device. The following pages describe how it works.

kinetic-glass-bending-device-principle-start

The device at rest. A glass sheet is placed, forming rollers are hooked up.

kinetic-glass-bending-device-principle-inmidst-process

Heated up to ~600°C the sheet becomes ductile and the forming rollers obey gravity.

kinetic-glass-bending-device-principle-process-end

In the end they do exactly what we’re after.

So much for theory – now for the practical part.

“Grau, teurer Freund, ist alle Theorie, und Grün des Lebens goldner Baum." Mephisto in Goethes Faust

Building the bending device started with a bunch of laser cut parts…

kinetic-glass-bending-device-marking-laser-cut-parts

…from stainless steel. Mild steel at temperatures > 600°C would…

assembling-bending-device-from-laser-cut-parts

…establish a flimsy oxide layer, which would likely spoil the workpiece.

kinetic-glass-bending-device-tig-welding

The structure got TIG welded together.

bending-device-polishing-weld-seams-with-angle-grinder

We assembled the rib structure precisely but were rather reluctant with welding.

A few beads proved stable enough and didn't cause a lot of thermal distortion.

Moving parts need clearance, otherwise they would get jammed due to thermal expansion.

finished-kinetic-bending-device-in-workshop

The finished bending device. Its shine quickly gave way to a dark patina in the heat of the kiln.

bending-preparation-cutting-ceramic-fiber paper

Inside the Glass Workshop: Cutting ceramic fiber paper – it serves as a mould release agent.

two-bending-devices-set-up-inside-fusing-kiln

Setup inside the cold kiln: Bending devices on pedestals of Vermiculite…

…they permit 180° pivoting of bending rollers.

Measuring the excess length of the 6mm glass sheet for the convex edge.

bending-device-inside-heating-up-furnace

A first peek through a scuttle while heating up the furnace. Nothing has moved thus far.

Half an hour later things looked already quite a bit different.

From this perspective it becomes obvious why those Vermiculite blocks were required.

The final postcard shot.

And here’s the result.

It can’t be denied though: We ran into a few issues too. The more precise our workpieces got...

...the more prone to breaking, due to shrinkage. Here’s a video of a fatal crash.

That’s why we, for the sake of prototyping eventually switched over to a somewhat more forgiving material...

...acrylic glass. It bends at lower temperatures and is elastic when cold. This meant that one could indeed release very precise workpieces which fit the mould closely. The actual bending process...

wasn’t any simpler though: Acrylic glass when warm has no intent whatsoever, to stick to...

...a particular shape. Countless bar clamps were required to fix the workpiece, until cold.

Intermediate results of this brute force method turned out greatly more precise after all.

Semi-finished c--c elements got formated using a circular saw. No problems here.

During the bending process however, elements had suffered numerous surface defects: We had to sand starting at grain 240 to get rid of blisters and blemishes. All elements were matt and opaque after this treatment. Using pneumatic machines...

…and also by hand we gradually sanded finer until grain 6000 was reached.

Time to mount the buffing pad then.

Things eventually started looking better.

There was a stack of shorter samples left.

We used these to simulate the appearance of c--c elements made from other materials.

White ash veneer on acrylic glass.

and Fiber Cement emulation on acrylic glass.

Finally, to complete the exhibit…

…elements were joined with the rack.

Holger Jahns presenting c--c at BAU 2015 in Munich in January 2015

photos: Julian Weninger for DETAIL magazine

Illustration for cold bending of glass. Two hands try to bend a strip of glass.

c--c is a prototype for a new type of Channel Glass. It was presented at DETAIL research lab, in Munich (01/2015) well as as at Glasstec 2014 in Düsseldorf (10/2014). For compact printable information please down- load this PDF in both German and English. What does c--c mean and how to pronounce this expression? I won’t be much of a help here, I’m afraid. These four characters happen to retrace the outer contour of the profile, that’s about all there’s to it. Where to purchase c--c? c--c profiles are not in production yet. Holger Jahns started his career as a craftsman: after his education in metal construction he trained as a cabinet maker. He then studied Interior Design in Amsterdam and finally graduated from a master class for carpentry and Interior Design in Graz, Austria. The practical approach has remained characteristic of his work as a designer – until today, Holger Jahns sees his work as the comprehensive analysis of both material and engineering processes. Any result will be approved only when performing well on site, in hands of construction workers. Looking at the material glass, Holger Jahns was amazed by the apparent lack of smart prefabricated items for specific solutions – in comparison to other construction materials and with glass being such an environmentally friendly material. To take the peculiarity of this material as an incentive stands at the core of this design research. Besides the work at his studio, Holger Jahns has taught for several years at Universität der Künste, Berlin and Free University of Bolzano, Italy. Holger Jahns Produktentwicklung Muskauer Straße 27 10997 Berlin www.konflux.net | re@konflux.net Legal notice: c--c is patent pending, Holger Jahns holds copyright for all graphics, unless indicated otherwisely. Press kit available upon request.

FIN

I would like to thank Oliver Döring for his ineffable contribution in this project. Thanks also to Andreas Walter who sublet his Glass workshop to folks without proven glass expertise. Holger