Methods of application of fluorescent inks and paints

Screen printing

The most effective printing technology, which uses fluorescent inks, is screen printing. It enables the application of the thickest layers of ink, which allows to achieve very good colour intensity and lightfastness. The majority of fluorescent inks have very poor lightfastness, due to their physico-chemical properties. Screen printing allows for an application of a relatively large volume of ink, which enables to achieve better lightfastness than in other printing technologies. Thanks to the possibility of applying thicker ink layer, the intensity of a fluorescent colour is also higher than elsewhere. The screen printing technology also allows to print on various surfaces and objects. This, next to pad printing , is probably the most versatile area of printing, thanks to the variety of substrates. Inks can be applied this way on paper, bottles, tubes, synthetic materials of many shapes, T-shirts, various kinds of fabric, boards, glass, furniture and many, many more.

Flexographic printing

The most efficient and high-volume printing technology, when it comes to fluorescent inks, is probably flexo printing. It is a very popular area of printing, which becomes more and more common each year. It is mainly used for printing labels and synthetic packaging, and that is why fluorescent inks in flexo are quite a popular solution. They are used for printing distinctive, bright labels, packagings, product markers as well as price tags, attached e.g. to discounted products or the ones that are supposed to stand out in a different way. Fluorescent inks are equally often used in UV flexo and water-based flexo printing. They are used most rarely in solvent-based flexo printing – although when any printing house uses these inks, it is for really large printing volumes.

Offset printing

Relatively large volumes with the best printing quality are achieved in offset printing. Fluorescent inks are quite often used in this technology, however, due to the inks’ properties, printed work is characterised by very poor lightfastness and relatively low intensity. Despite these disadvantages, offset printing houses use fluorescent inks quite often. Offset fluo inks are used for printing stickers, cutouts, inserts and advertisements in newspapers, selected types of labels and packagings, children’s books, fluorescent papers, etc. Offset printing allows to achieve relatively best quality of the print, therefore fluo inks can be used for printing small elements, text, inscriptions, etc. To obtain relatively high lightfastness and printing intensity, sometimes the ink should be applied twice (or from two printing units).

Other printing technologies

Fluorescent inks are generally used in all the printing technologies. Each of them possesses its unique specifics when it comes to fluorescent inks; however, due to the nature of this article, they will not be presented here. In order to picture the wide range of methods of printing fluorescent inks, they should be mentioned. These technologies are: digital printing, letterpress, gravure, pad printing, dry offset, waterless offset.

Construction – paints for wood and metal

Fluorescent paints are also used in construction. They can be applied on wood and metal by using a paintbrush, roller, or machine, using the airbrush method. Fluorescent paints are not opaque, they are rather transparent, therefore it is best to apply an opaque white base coat before use. These paints have also low intensity. In order to improve it, sometimes the paint needs to be applied two or three times. The mose precise and detailing method of application is a spray painting gun. However, the biggest loss of paint occurs while using this method. The brush will be the best choice if whe would like to achieve the thickest layer of paint.

Construction – paints for roads, floors and difficult surfaces

One of the biggest challenges facing the paint producing company is their application to difficult substrates or surfaces exposed to strong weather phenomena such as rainfalls, sunlight, winds, constant pressure or abrasion. Such paints require the use of special binders, hardeners, ultraviolet radiation absorbers and other additives which improve the longevity of the coating. Therre are paint manufacturing companies which, knowing needs of their customer and having various binders, rheological additives or surfactants ar their disposal, are able to skillfully match paints to their customer’s requirements.

Construction – paints for walls and building facades

Paints for walls and facades are relatively easy in both production and application. The most popular are, of course, water-based paints, which do not require sophisticated preparation other than preparing the surface in order to support the adhesion of the paint to the substrate. Fluorescent paints for walls and building facades can be applied with a paintbrush as well as roller or other wall painting device. If the application of the fluorescent paint happens to take place in sunny or highly lit places, it should be kept in mind that these paints have very poor lightfastness and will quickly fade or darken in such conditions.

Industry – paints for metal and wooden machinery and devices

Fluorescent paints are widely used in industry, they serve for marking machinery, devices, part of equipment and infrastructure. These paints are usually meant for metal, wood, sometimes plastics. Oil or solvent-based paints are usually used on such substrates and they can be applied in a number of ways, from an ordinary paintbrush, to the complex and precise airbrush. Since fluirescent paints are characterised by their unique brilliance, brightness and purity of colour (a kind of ‘glowing’), they are used for marking areas which are required to be especially distinguished. They are also used (in their ‘invisible fluo’ variation) as markers visible only under UV light. For example, they serve as an information visible only under ultraviolet to sorting machines, but completely invisible to the end customer, since these paints are transparent in an ordinary light.

Industry – paints for theatre and event installations

Fluorescent paints are often used for creation of staging for theatre, TV, or events requiring special effects. In the daylight they stand out from other paints with their exceptional brightness and expressiveness. Another type of fluorescent paints – invisible in the daylight – gets used for production of arrangements which are to become visible only after turning on the UV lamps. Paints or inks for event-related installations are applied in many ways, depending on materials used, artistic requirements, expectations of creators or the level of complexity of the project itself – from an ordinary paintbrush or roller to the high-fromat printing machine. Both water- and solvent-based paints, even paints cured by UV radiation, can be used for these purposes.

Industry – paints for marking boards, signs, etc.

Fluorescent industrial paints are most often used for marking all kinds of information and warning boards, important infrastructure areas, boards, signs, placards, acronyms that are supposed to attract special attention to the place and information given by the sign. These paints are most often applied on synthetic substrates which require specific types of binders. These paints are most often solvent-based or cured by UV rays, because both those types have exceptional adhesion properties.

Paints cured by UV rays and visible under UV

Since the expressions „paints visible under UV” and „paints cured by UV” appear so often in this article, it should be pointed out that these two phenomena are completely unrelated to one another. The expression „paints visible under UV” is about paints, which are transparent in the white light (or simply, „daylight”) and visible only in the UV light (essentially its UV-A range), whereas the expression „paints cured by UV” is about paints where the crosslinking (‘drying) process of these paints begins under the influence of ultraviolet radiation (UV-C range).