by Helen Rallis, field product manager – coatings, Sun Chemical
Printers and brand owners always are looking for ways to distinguish their product through the use of special effects coatings. Specialty coatings can offer a variety of multi-sensory special effects that stand out, including glitter, pearlescent, scented and tactile coatings. In order to make print “pop” on the shelf, it is important to apply the coating correctly so it can be used to the best advantage. This article will act as a guide that will describe some of the effects available in the market today, along with recommendations for how to apply them effectively.
As a general rule, the more coating weight applied to the substrate, the more pronounced of an effect you would expect to experience. Anyone who is just starting to utilize these types of coatings will need to be willing to experiment to find the best combination that will suit their needs. If too much coating is put down, the user might experience cure problems, so the correct balance between effect and application parameters must be sought out.
Because of the coating weight requirements, these types of effects were historically achieved only through screen or gravure printing processes, which are known to apply a thicker deposit of the coating onto the substrate. For short- and medium-sized sheet-fed applications, an offline screen coater is the logical choice for specialty coatings. In recent years, flexo applied coatings also have been used. This is because the equipment manufacturers have worked toward getting coaters and aniloxes that can deposit more coating on the substrate. While the printer might need to invest in a number of diverse aniloxes to apply specialty coatings, equipment has evolved so that changing aniloxes has become much easier and faster.
Another consideration when applying special effects coatings is the design. Flood coating the page may not necessarily give the best effect. Sometimes a simple highlight can attract the eye. When adding many of the visual effects, a dark background will help provide good contrast and make the effects stand out more.
Glitter coatings are made with large particles that reflect light at different angles to produce a sparkle or shimmer effect. They come in silver, gold and various colors that also can give a rainbow effect. The particle sizes of the glitter pigments can start at about 50 microns and go higher. These are best applied with an offline roller coater, but screen printing or flexo printing process also can be used.
When applying the glitter coatings, a mesh of 60-110 threads per inch (tpi) of monofilament polyester is recommended. Higher mesh counts can result in the filtering out of the glitter particle. When flexo printing at least a 25 BCM (billion cubic microns) volume for the anilox, it is recommended to allow for particles to flow in and out with ease. This will deposit enough onto the substrate to stand out on the print.
Texture or reticulation coatings
When applied, reticulation coatings give an “orange peel” texture to a print surface. This process can be used as a cost-saving alternative to textured embossing. There are a number of ways to produce this effect, which includes a roller or screen coater.
A textured UV coating also can be applied inline with a “strike-through” process on an offset press. In the litho station, an overprint varnish (OPV) is printed but not cured. In the coating station, a UV coating is applied. In the areas where it touches ink or paper, it cures to a nice glossy finish. Everything then goes through the UV lamps and is cured. In the areas where it touches the litho-applied OPV, it reticulates to form the embossed-like stippled texture.
There is a flexo coating that produces this effect as well. In order to feel it, a minimum anilox volume of 20 BCM is required. There also is a screen-printed version which can be applied using a 200-250 thread per inch mesh.
Raised image coating
Raised image or emboss coatings are high-viscosity coatings designed to give a raised textured effect. These are typically applied in some kind of pattern, like water droplets on a leaf or pebbles on a beach or alligator skin. The key to getting this effect is to put a great deal of coating down. When using a screen coater, a mesh of 110 to 180 threads per inch is recommended. For flexo applications, use a minimum anilox volume of 40 BCM.
Pearlescent and color shift coatings
Pearlescent coatings have an iridescent luster that can add elegance to the printed product. They come in a variety of effects and colors.
Color shift coatings are a specific subset of pearlescent coatings that will change color based on the angle of view. These come in a variety of particle sizes, varying from 10 to 100 microns. Typical pigments used require a minimum of 10 to 15 BCM in flexo applications. For screen applications, a mesh of 300 tpi or lower can be used.
Soft-touch haptic coatings are matte coatings that cure and provide a soft leathery feel. These types of coatings can be used to replace soft-touch laminate films. For screen coater applications, the use of 200 tpi mesh or finer is recommended. For flexo applications, apply the coatings using a 12 to 14 BCM anilox coater.
It is important to note that the most commonly used soft-touch coating is not compatible with normal UV inks and coatings. So, it is very important to clean out equipment thoroughly before and after use. A special wash is required.
There are variations on the soft-touch coatings that are more compatible with conventional UV chemistry. These have a slightly different feel to them, however, so it is important to experiment and find the right product for the application.
Sandy-feel coatings are designed to give a rough sandpaper-like texture to the print. These come in a variety of gloss levels and textures – from fine to very coarse. The particle sizes on this type of material vary, so this needs to be taken into consideration when choosing an anilox roller. Typically, a minimum anilox volume of 25 BCM is recommended to apply this coating with a flexographic process. For a screen coater, a 200-250 tpi mesh count would be ideal.
Aroma coatings are coatings which contain microencapsulated fragrance oils. The scent remains inactive until consumers handle the print, trigger a release and experience the product’s aroma. These coatings should be applied thick enough in order to achieve the proper effect and scent.
More brand owners are requesting the use of special effects coatings on their products in an effort to make an impression. Specialty coatings can add value to a finished printed product by providing differentiation, but printers have to be willing to experiment with their equipment configuration to get the desired effect.
Helen Rallis has over 20 years of expertise with flexible packaging coatings and currently works as a field product manager for coatings at Sun Chemical. To learn more about Sun Chemical’s SunInspire™ specialty coatings or SunScent™ aroma coatings, visit www.sunchemical.com/naicoatings or call 708.236.3798.