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KEY TO SUCCESS

Company: Clients with window storefronts     

Project: Projecting onto windows    

Key to success: Most vinyl manufacturers make specialized products to create vivid and dynamic window displays generated from a projector. The displays can be static or video, and still look great. 

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Vikuiti Rear Projection Film mounted to glass on street facing window. Photo courtesy of 3M and Spyeglass.

Wouldn’t it be cool if you could turn any window into a TV screen? How about taking it to the next level and turning that same window into an interactive touch screen display? This may seem like a technically incomprehensible or ridiculously expensive undertaking, but you may be surprised to learn just how simple and affordable it can be.

To accomplish this feat, you must have an un-tinted window, a video projector, a computer or media player, and a textured film that will transmit an image projected onto the back through to the viewer on the other side. Of course, for any window visible from the street, you may have to get a permit, but that is a subject worthy of another article.

 

When deciding which screen material to use, the viewing distance, the placement of the projector and the ambient light situation all must be considered. The cost of the various materials ranges vary widely, along with the quality of the projected image.

 

This is how it works: the textured side of the screen material faces the projector, diffusing the light and reflecting it through the window toward the viewer. The texture looks very similar to that of etched or frosted vinyl, and those familiar sign materials will produce an acceptable image for some situations. However, when your client needs a high contrast, higher definition image that is visible in bright sunlight without showing a hot spot from the video projector, one of the optical screen materials designed for this purpose might be worth the investment. 

 

There are three types of material to choose from; diffusion films such as etched vinyl and window tint, and specially designed optical video screen film. The lowest cost material is also the most familiar to sign makers. Oracal, Arlon, 3M, Avery, Universal Products, FDC, and MACtac all offer some form of etched or frosted vinyl, available in up to 60" rolls. All of these will transmit a projected image with varying degrees of crispness and contrast, but they will wash out in bright ambient light, and they are not designed to minimize hot spots. When applying, they must be masked to prevent stretching, and large pieces should be hinged and applied with plenty of application fluid.

 

Decorative Films conducted tests at New York University of their diffusion window tint films compared to optical screen films, and found them to be comparable in image quality, brightness, viewing angle and hot spot reduction under optimal light conditions.

Window tint film has a texture and feels very similar to the projection screen material. In fact, in tests conducted at New York State University, two of the Solyx window tint films, the SX-324 Frosted Sparkle and SX-WF-WM White Matte really stood out as visually equivalent when compared for brightness, viewing angle, image sharpness and hot spot reduction. 

 

The films designed for image projection work like the optics of the human eye, with glass beads precisely angled to direct the projected image through while deflecting ambient light, resulting in a higher contrast image with purer blacks and whites, and visible on exterior windows in full sunlight. Both of these materials require very different handling and application methods, more familiar to window tint installers than sign makers.

 

With the optical screen films it is also possible to add interactive touch sensitive technology into the mix, with a separate layer of material laced with a grid of fine wire and connected via USB cable to the computer interface. This application is appropriate for directories, menu boards, catalogs, and any location where the audience has an opportunity to approach and interact with the graphics. 

 

In every installation, it is critical to remove all traces of dirt, paint, adhesive, silicon, and to minimize static electricity and potential contaminants. If adhesive must be removed from the window with solvents or ammonia-based cleaners, it would be safer to allow 24 hours before applying the screen material. The glass temperature and atmospheric humidity will also have a huge effect on the success of the application. The biggest difference between vinyl and the screen or tint film is that the film is much thicker and dimensionally stable, more like a thin polystyrene sheet. The release liner is clear and much thinner, unlike the paper release liner on vinyl rolls. No masking is required, and the hinge technique is not recommended.

 

After carefully cutting the material to the correct size, the meticulously cleaned window should be sprayed liberally with an application fluid such as RapidTac or Gila, or water with a few drops of unscented dish detergent. In very cold conditions, where the application fluid tends to freeze on the glass, windshield wiper fluid also works well.

 

The screen film should be stuck to the window with the release liner facing you to hold the material while the liner is removed, away from dirt and contaminants, in a low static environment. Immediately flood the exposed adhesive with fluid, then lift the screen material from the window, turn it around, flood the window again, and position the screen on the glass. For larger sheets, at least two people will be required to rotate the film. The fluid should then be worked out from the center with a rubber roller or vinyl squeegee covered with a friction sleeve, until all air bubbles are eliminated. Felt squeegees aren’t rigid enough to work well with the thicker screen material. Scratches or burnish marks cannot be polished away, so it is important to be firm but gentle, and always use the right tools.

 

As with vinyl application, any dry spots can trap air bubbles or damage the adhesive, leaving unacceptable marks beneath the screen material. You should explain to the client that there may be fluid remaining behind the material, which will evaporate over 24-72 hours. If any air bubbles remain after the adhesive has cured, they are easier to eliminate from vinyl than from either of the more rigid films. A very sharp pin tool is recommended, never an exacto knife, because the slit created may shrink away and result in a light leak. Bubbles the size of a pencil eraser or larger are worth the effort, but tiny “champagne” bubbles will not be visible with the image projected, and will eventually disappear on their own. 

 

One of the things that makes rear projection on glass different from dynamic digital screens is the ability to cut the material into shapes and combine it with opaque or perforated vinyl to create unique graphic images with moving components. The vinyl materials can be cut with a sign shop’s plotter, but the thickness of the window tint film and the tiny glass beads embedded in the screen materials make them more difficult to cut. It can be done with a flatbed CNC router, by hand with a knife, or by sending a vector file to the dealer to have it cut to shape prior to shipping.

 

Some of the films are also available with repositionable adhesive, which makes them portable and re-usable. The rear projection screens are also available in rigid acrylic, which can be cut to custom sizes and shapes and suspended or mounted freestanding within a store or behind a window to offer another portable graphic alternative.

 

Another factor to consider in choosing the right material is availability. Most brands of etched and frosted vinyl are easily ordered through your usual sign supplier, and depending on the size and brand, will usually be in stock or drop shipped from the manufacturer within a few days. You may have to order a ten-yard minimum, but the cost will probably still be less than that of the projection screen material cut to size.

 

The window tint films are available through distributors, who are happy to sell small or large quantities and often willing to offer wholesale pricing to resellers, such as window tinters or sign shops. Most films are available in 48" and 60" rolls and custom lengths, in stock and ready to ship within 24 hours.

 

The projection screen materials are not only much more expensive, but often less immediately available, and sometimes only through an authorized dealer. It is possible for a sign shop to qualify to become a dealer and benefit from significant discounts and customer support, including referrals to Audio/Visual technicians, graphic content designers and programmers, and experienced installers. 

 

Screen dealers also offer demo kits which will allow you to demonstrate the rear projection and interactive touch screens in your showroom or clients’ locations, generating interest and hopefully sales. This kind of customer support is not available from vinyl or window tint suppliers, so it would be up to the sign maker to establish their own network of subcontractors to provide the complete package.

 

The most popular applications for rear projection screens include retail stores, malls, nightclubs, bars, restaurants, casinos, car dealerships, directory kiosks, menu boards, trade shows, military, government, banks, travel agents, real estate offices and hospitals. Wherever a client wants to engage their customers with video of their products, or even better, draw them in to interact with a touch screen, rear projection materials on an existing window may be the most cost-effective solution.

 

Any time a sign maker wants to offer a new product to their clients, it is important to research the options available, build relationships with new suppliers and subcontractors, and educate themselves so that they can confidently design and sell an effective visual display that will fill their clients’ needs without breaking their budget. Rear projection video screens are one more exciting new development for the creative sign maker to add to their repertoire.