Silicone Sets the Stage

Israeli designer Ron Arad invented a gigantic 360° canvas for the Roundhouse Theatre in London. The curtain experiments with light and material in a revolutionary way and has been a crowd-pleaser around the world. The Curtain Call installation is made of WACKER silicone rubber.

The canvas is used from both sides. The audience can part the curtain at any point on either side and walk through it while the images projected on a cylinder-shaped area spanning 500 square meters fall into place around them. At the same time, the canvas reveals the real world behind the scenes. This kind of vast curtain had never been seen prior to its premiere in the summer of 2011. Consisting of 5,600 suspended ceiling-to-floor rods, Curtain Call, a 360° installation created by industrial designer and architect Ron Arad, enthralled the audience at London’s Roundhouse Theatre, a former railway engine shed dating back to the 19th century. “I didn’t tell the audience how to use the curtain. I wanted them to be curious and delighted,” said the London-based Israeli in an interview.

Versatile Material

The stability of the silicone rubber is checked in a WACKER laboratory in Burghausen using a tensile tester. The mechanical resistance is crucial so as to enable the audience to touch the curtain without causing any damage.

Arad owes the resounding success of his idea, which has subsequently been installed at other locations, to his creativity and the versatile properties of the silicone rubber used to create Curtain Call. “The idea had us hooked right from the start. Ron had a totally new take on how to use our products,” said Nick Soudah, managing director of Silex Silicones Ltd. The British silicone manufacturer from Bordon, 30 kilometers north of Portsmouth, immediately knew which material had the requisite properties: WACKER’s ELASTOSIL® solid silicone rubber.

This class of high-temperature vulcanizing silicone rubber has been tried and proven as a reliable material for a range of extremely varied applications for over 70 years. It is the standard material used for manufacturing hoses, seals, membranes and molded parts in the medical-technology, pharmaceutical and food industries. The properties can be varied by using additives. For example, heat resistance is achieved with stabilizers and pigment pastes regulate light permeability. By adding a catalyst, the raw silicone rubber’s base materials bond during heating to form a three-dimensional network, which experts call curing. “That’s why WACKER’s solid rubber grades offers high elasticity and good mechanical properties,” explained Dr. Andreas Bacher, head of technical service engineering at WACKER SILICONES.

Silex, a British manufacturer, chose a particularly light-permeable silicone rubber for Curtain Call.

The audience can touch the curtain and even pull at it without causing any damage. “Its high translucency means it transmits light well and the audience can see the projected images from all sides – the perfect medium for the canvas project,” he added. The silicone rubber used for the curtain is cured during the manufacturing process – that is, it becomes an elastomer. Organic peroxides or platinum-catalyzed additives can be used for this purpose. Silex Silicones Ltd. used a platinum-curing system. Arad’s artwork required a few adjustments to the usual production process. “Our many years of experience stood us in good stead and we quickly came up with a solution to the problems,” said Soudah.

Viewing from Both Sides

Comparison of uncured filled polymer and cured rubber. Left: Uncured polymer with filler. Right: Polymer with chemical crosslinks (red) forms a filled, elastic network.

First, the light permeability had to be ensured to allow the images to be viewed from both sides. Addition-curing systems produced the desired translucence of the silicone rods while protecting them from yellowing. The length of the rods presented another challenge. The base material was heated at the beginning of the manufacturing process, and then pressed into shape by the extruder. “The usual procedure of reheating the tubes would have made them inflexible,” he noted. Once they had been cut to size, they were stored lying flat. And that’s how a base material resembling modeling clay was transformed into 5,600 rods measuring eight to ten meters with a diameter of 1 centimeter. Arranged in a row, they span a distance of 37 kilometers. The quality of the material would have allowed for a length of 20 meters, “but no one has asked for this specification,” said Soudah.

Long, Flexible Rods

The backlit Curtain Call installation makes it possible to show different visual elements or even movies.

The impressive show drew other customers to Silex. Titled 720°, the curtain was set up in the Israel Museum in Jerusalem as a stage for several film and music events in 2012. Ford used the concept to stage its presence at the 2013 Frankfurt Motor Show. Its new models premiered by driving through the curtain in full view of the public. The Olympic Museum in Lausanne (Switzerland) purchased a similar curtain for its permanent exhibition. And British fashion label Top Shop has also discovered the principle of long, flexible tubes. Dyed in different colors, they were arranged across retail space to symbolize the strings of a harp. Roundhouse repeated its success with Curtain Call on the theater’s 50th anniversary in 2016.

For Silex’s managing director, the curtain demonstrated how imagination and creativity can reinvent commonplace materials to create something entirely new. Soudah was invited to the premiere in London in 2011; it was an unforgettable evening: “I was both proud and impressed to experience our product live in action. I got goose bumps.”