UV Coating, also known as ultraviolet coating, is a kind of surface treatment, which comes in liquid form. It is applied to printed paper or other surfaces to give a glossy and shiny finish. This coating is cured or hardens when exposed to ultraviolet light from a specialized source. This coating can also be applied to protect a material from the degrading effects of the sun’s rays.
The UV coating can be added to various substrates, but usually, this kind is mostly used on printing paper. It can also be used to coat plastic, glass, wood and even metals, such as cans of beverages etc. and many other surfaces.
To be able to achieve UV coatings, those special dyes and inks have to be cured, that is they have to be dried. We know that the sun emits ultraviolet rays, however, that can’t be used in this situation. There are special devices for such. The process by which this happens is not evaporation as some of us would think. It actually happens through a process called polymerization.
Types of UV Curing
Mercury Vapour
They are what is accepted industry-wide and they are also very versatile, so they could fit into a variety of applications. These special bulbs contain Mercury, and when high voltage electricity passes through the bulb the mercury vapourises. This process brings about the emission of ultraviolet rays. the range of the UV rays comes within 240nm-270nm and 350-380nm. This high intensity of these rays is what brings about the curing of the coatings.
UV LED Curing
These are the most popular UV LED curing lamps in the market at the moment. This is quite a new technology, it has loads of advantages over mercury vapor curing. Ultraviolet led curing is becoming popular, this is because it produces better results in some areas. However, in some other areas, it doesn’t serve very much. This is still new though and a lot of work is still being done on it.
Fluorescent Curing Lamps
This is not the type of fluorescent lamps used in our homes. This one is specially made for curing. They can emit rays across a wider range of frequencies as compared to LED or Mercury Curing. Therefore these lamps have multiple uses and they are also much cheaper than both LED and Mercury Curing ones. However, the quality of finish is inferior to the other two.
Why UV Coating
UV coating is used for aesthetic purposes and also functional purposes. It gives gloss and shine to printed paper. It also protects the paper against scratches, fingerprints, and basically denting while handling.
So this is a very important process used in printing especially when the products will have to pass through the mail, in the process of posting, and the many hands it will go through. As long as the pieces will be handled frequently, the paper should better be coated.
Is UV Coating Affecting the Environment?
It’s important to take into consideration the impact of UV coating on the environment. In the past, this was indeed a real issue, however, most nowadays curing devices are based on eco-friendly formulas, therefore, they are environment-friendly.
Aqueous Coating, Plastic Lamination or UV Coating?
The UV coating is sturdier than aqueous coating, so it will offer more protection, but it is not as hard as plastic lamination.
This gives the added advantage of being cheap to attain. Also, it dries even faster, almost instantly. So there’s less time wasted, less power consumed and more can be done in lesser time with UV Coating.
Advantages of UV Coating
Very glossy finish
Applying it to deep colors like black and darker blue, deep earthy shades gives very attractive outputs. The result is a very slick appearance. It’s perfect for fashion magazines, catalogs, and projects where artistic images matters.
Great Abrasion Resistance
For those who know the printed piece will be going through many hands before getting to the end user, it can go a long way to protect and keep the visual integrity of the piece. It will also serve to keep away fingerprints, smudges and other little things that might just ruin the appearance of a perfect paper file. So by the time it gets to the end user the paper still looks as good as new.
High Clarity
It can be used to highlight a certain part of a text to make it stand out. Logos, names, etc. wherever is applied it tends to bring out the detailing and the finer point of the images. Photographic projects, brand images, company logos, promotional pieces that aim to grab attention and the likes should definitely be coated.
Environmentally Friendly
The process doesn’t release volatile chemical compounds, the lamps are also free of solvent or VOCs(evaporating solvents) when curing.
Fast Drying
UV coated products dry almost immediately they’ve gone through the UV light machine. So this reduces the amount of space needed to keep the printed products to dry. It also enables more efficient production times and faster delivery.
Versatile and Cheap
The high solid content in ultraviolet formulation gives room for the coating to be applied very thinly unto surfaces. This also gives versatility, as it can be formulated to suit a wide variety of purposes and surfaces.
Disadvantages of UV Coating
It has been known to crack when the paper is folded or when it is scored. Of course, cracking defeats one of the major purposes of UV rays.
Due to the fact of the glossy and slick nature of printed paper, there’ll be difficulty in applying other things to the paper. Such as ink application in the form or writing becomes very difficult, also rubber stamping too can be very difficult. Such surfaces can’t accept adhesives or any other forms of imprinting, so if you intend to write on a section of that paper, make sure it is not coated.
Applications
Ultraviolet Coating of Glass
The UV coating is not only limited to printed paper but as said earlier, it is the most known use. It is not just used for protecting surfaces from scratches and so on, it can also be used to limit the effect of the rays on a surface, as in the case of glass and plastic. Transparent glasses and plastic can be coated with an Ultraviolet coating to reduce the number of rays that can go through the glass. We find such application in the windscreen of vehicles, the visor of helmets and also in eyeglasses, both sun shades and glasses for correcting eye defects.
They can be applied in a variety of ways, such as roll, dip, spray, roll jut to mention a few. In fact, this is one of the best finishes for plastic parts, since heat is not involved, therefore there’s no likelihood of the plastic being deformed due to heat.
Ultraviolet Coating on Aluminium Cans
These are cans used for the packaging of edible liquids, such as juice, coffee, and the likes. Special care is given to Aluminium cans for beverages especially those for edible stuff. They are washed several times and then cleaned. Then the Aluminium cans are coated with ink, several colors of ink are impacted onto the outer part of the Aluminium cans.
The inside is also coated for health purposes. Now after the whole printing process has taken place, the cans are passed through UV light, of about 100f and then both the inside of the can and the outside of the can are cured by rays. Now, this coating protects the can from multiple possible damaging agents.
Ultraviolet Coating on Wood
Coatings that are curable on wood can be expensive, especially as compared to conventional methods. There are basically three methods of curable coatings for wood. We have a water reduced curable coating, solvent reduced curable coating and 100% UV curable coating.
They can be applied by almost any application method independent of the option used. However what determines what kind to be used is the exact kind of finish that is expected. And also what kind of wood and the surface property of the wood to be used.
If thick films are required for the finishing on the wood, then the 100% coating should be used. If what is required is thin though, then the water-based curable coating should be used. Of the three methods, the 100% curable options are the most versatile, and also the most economical to set up in the long run.
In printing paper
They are used in printing paper to give it gloss and luster, making the printed product extremely reflective and shiny. It is also used to form a protective sheen on the paper, so as to make the printed material last longer and retain aesthetic integrity.
Wrapping up, UV Coating can be used on plastic and glasses to reduce the effect of UV rays on these surfaces. So sometimes the coating offers reflective properties which bend the light, preventing a direct impact from going through the glass.
Inwood just as in paper it is used as a form of finishing, to provide luster and gloss on the wood.
Apart from uses in the lab and factory, they can be used on floors, walls and other surfaces to impart beauty. Technological advances are still being made in the area of using UV curable coatings outside the laboratory and the factory.
Conclusion
UV Coating can be applied using virtually all ink application methods. It can also be adapted for a majority of substrates. It’s a fast process, environmentally friendly and adds some pop and slickness to printed materials.
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