LONDON.- Random International, the specialist art collective, has developed a unique installation piece that uses light to create transient images on a large photosensitive canvas. Designed to highlight the ephemeral nature of digital data, the installation - known as the 'Temporary Printing Machine' - invites viewers to witness the creation and almost immediate decay of text and images, and to question their relationship with such information sources.

Random International is a London-based arts group that specialises in the design and implementation of unique experiential exhibitions, installations, commissioned works and performance projects. It works at the fringes of innovation in science, art and design, developing installations that reinterpret the 'cold' nature of digital technology to emphasise its analogue aspects. The collective has won a number of prestigious design awards since its foundation in 2002, and its work is regularly commissioned by leading art galleries, theatres, exhibition organisers and commercial blue-chip companies.

The prototype Temporary Printing Machine was developed as the result of a joint commission from Creative Review magazine and Selfridges of London, and formed a window display in this famous store, where it attracted considerable attention. According to Hannes Koch, one of the founders of Random International, "This machine taught us a valuable lesson about designing for reliability. It had to perform continuously, day after day, which placed a considerable strain on its moving parts. As a consequence, when it came to designing its successor we looked around for a manufacturer of industrial strength motion control components and chose Festo, primarily on the strength of the company's excellent reputation for quality products."

The final version of Random International's Temporary Printing Machine is being produced in a limited edition of 15, and makes extensive use of Festo automation components. Each machine comprises a large canvas covered in a pigment that is reactive to ultra-violet light, a pair of linear actuators hidden behind the vertical frames, and a horizontal scanning bar equipped with an array of UV LEDs. A built-in raster processing system, synchronised to the vertical movement of the scanning bar, converts the images to pulses of LED drive current, one line at a time.

The overall frame size, scanning rate, image persistence and resolution vary according to customers' demands, but a typical machine measures 1.7 x 1.2 metres and is fitted with a 128-LED scanning bar to achieve a relatively coarse horizontal resolution for maximum artistic effect. The images are monochromatic and generally have a persistence of about two minutes; as soon as an image has faded away it can be replaced by another of the same, or a completely new one, creating an infinite stream of appearing and disappearing data.

The two linear actuators are Festo DGE-RF electromechanical units; these toothed belt axes feature an internal roller guide and are virtually silent in use, which makes them ideal for this particular application. They are also exceptionally well lubricated - there are sufficient grease reserves for 10,000 km of travel, and even then, these can be replenished without having to reach into the housing. The machine's horizontal scanning bar also functions as a torsion coupling between the two actuators, with only one side driven. Random International offers a choice of stepper and servo drives, depending on customers' preferences in terms of image refresh rate, smoothness and acoustic noise. For installations that are intended to be hung in very quiet environments, such as domestic living rooms, the company generally recommends use of Festo's MTR-DCI intelligent servo motor, which is capable of very smooth, low noise operation.

As well as being very pleased with the dynamic performance and reliability of Festo equipment, Random International's Director, Flo Ortkrass, is especially impressed with the level of service provided by the company: "In our line of work we are very unlikely to become a high volume user of Festo equipment, but the company consistently treats us as if we were about to place an order for equipping an entire factory with automation! Festo really are amazingly supportive, and we look forward to a long and successful association."

The first Temporary Printing Machine is currently on display at the Christopher Henry Gallery in New York City.