Most window films can be printed with graphics through a variety of ways, including solvent-based and ultraviolet-curing (UV-curing) screenprinting; solvent, eco-solvent and UV inkjet printing; conventional and UV offset printing; and aqueous, solvent and UV flexographic printing. In some cases, a primer is necessary first.
The prints will retain their vibrancy if properly protected. Overlaminates will be useful in protecting images against abrasion when severe precipitation could affect the window graphics, while others with UV-inhibiting properties can prevent image fading. Signmakers are a valuable resource for retailers at this stage, ensuring the correct inks, preparations and overlaminates are selected.
Cold or hot?
It is worth keeping in mind that exposure to winter elements does not always mean sub-zero temperatures for window graphics.
Windows exposed to sunshine can become warmer than the ambient temperature throughout the day. Depending upon their specific graphic design, up to 95 per cent of solar radiation can be absorbed by dark printed graphics, which will rapidly increase the temperature not only of the film, but also of the glass. This can affect both exterior and interior surface applications, even when the graphics only cover a small portion of a window’s area.
In some cases, this phenomenon can lead to thermal expansion and even breakage of the glass if the window pane is tightly mounted to its frame. It is therefore advisable to try to avoid large areas of dark and light contrasting shades in window graphics.
Surface preparation
To make sure window graphics last throughout the winter, whichever surface the pressure-sensitive adhesive films are to be applied will first need to be clean. This may seem obvious, but there are a lot of surface-related considerations at this stage, whether installing indoors or outdoors.
Testing
It is always recommended to test the intended surface before full installation. The signmaker should ask the business owner or manager if any type of wax, rain repellant or anti-graffiti chemical has been used on the windows. If so, they will need to be thoroughly cleaned again before graphic application.
Tinting or anti-scratch coatings should be detected early as well, as these can sometimes be damaged later on during the graphic removal process. Any interior windows that tend to develop condensation should also be avoided.
The graphic material should be tested for adhesion with the window surface in a clean, inconspicuous area and allowed to ‘dwell’ for 72 hours. If it shows signs of lifting, it may need to be re-squeegeed. And if it still lifts after re-squeegeeing, an edge sealant may be needed.
Cleaning
Generally, an orange or other citrus-based cleaner, degreaser or high-strength cleaning solvent can be used. And the window’s surface will need not only to be thoroughly cleaned, but also properly dried, before any application of graphics.
Ammonia-based cleaners should be avoided. It is best to mix a soapy solution with four teaspoons of detergent to one gallon of lukewarm water, making sure detergent contains no lotions, creams, fragrances or other additives that could impede proper adhesion of the window graphic.
As a final step, the glass should be cleaned with rubbing alcohol and immediately wiped dry with paper or lint-free towels.
