In general, backlit images are meant to be viewed only when a light source is behind the image. Occasionally, however you may need to create a backlit image that can be viewed when face-lit with natural light in the daytime, and also at night when the image is illuminated from behind. The problem is that a print that looks good when backlit needs to be have a heavy ink load. It needs to be dark and dense to compensate for strong backlighting. But that same print will look terrible in a front-lit application. Here are some tips to get around the problem.

• Print the graphic twice using non-backlit print density with a thin translucent white backing between the two print layers.
   
• When the backlighting is off, only the top layer can be seen because the white inner layer blocks the second print.
   
• When the box is lit, the light shines through all layers, giving it the added density that backlighting requires.
   
• Use a good light table when mounting the three layers. Having an exact match of the two prints is crucial.
   
• Be sure the light box lighting you choose offers a color signature that is acceptable to the client (both fluorescent and LED lighting systems present different sets of color casts).

The type of printer, inks and media being used also makes a radical difference in the appearance of the final print. Laser-based digital photo imagers have the most scope for adjustment. Prints from these machines tend to have the most brilliant backlit qualities. They can easily be adjusted to almost any density and color range, but are not perfect. The prints fade rapidly, are not water-resistant and can be expensive.

Dye-based aqueous inkjet inks look good and are inexpensive, but they tend to fade rapidly and are not waterproof. Pigment-based aqueous don’t fade, but also are not waterproof. Solvent inkjet inks are inexpensive, waterproof and much more fade resistant. Each type and brand of printing media and laminate will also give prints a unique color cast. Different applications will need different usage of each of these processes and media.