Adhesives and Label Security

Believe it or not, a label’s ability to provide security is directly related to the self-adhesive that’s being used. Basically, a self-adhesive is a chemical fastening system that isn’t heat-activated or activated by the evaporation of a solvent. Rather, the self-adhesive is activated by the application of pressure. It is only through the strength of an adhesive that the other elements of security labels like the substrate, seal or lamination on a label can be deemed effective.

Today’s adhesives, thanks to modern chemistry are able to provide labels with all of the needed properties for the increase and maintenance of security. But adhesives go beyond simply applying a label to a surface; adhesives can also be used to achieve certain label properties.

Opacity vs. Transparency

When an adhesive is loaded with aluminium powder, and then opaque materials are selected such as metallised film, opacity is achieved. It can also be achieved by printing labels using a single or series of particular printing processes.

Transparency is actually the more difficult property to achieve. There is a high demand for transparent labels, especially for ‘invisible’ style labels. Where ever the protection of documents, photographs or other security label elements is required, testing must occur beyond the lab.

Elements of Transparency Testing

Of course, the testing of any adhesive should occur in the laboratory. But even if real-world conditions can be replicated in a laboratory, real-world testing should also occur. For example, if a security label is supposed to adhere to a vehicle’s window, the fact that it will be exposed to all intensities of light and temperature should definitely be considered.

But in addition to that, it’s the fact that light and intensity will affect the label on both sides. A vehicle’s interior temperature can vary greatly from the temperature outside the vehicle. And a label’s temperature on the outer-facing side may also vary greatly on its inner-facing side.

The ability of a transparent label to be repositioned is another element that needs to be considered. As well, a label’s ability to be repositioned can also be affected by both internal and external temperatures. However, the client’s needs must also be thought of. If a client requires their labels to be permanently affixed, this will require a different set of properties than a client needing a highly-repositionable label.

Materials being adhered to

Understandably, there is a level of concern with regard to the potential damage of surfaces that labels are being adhered to. Indeed, there are several potential complications, especially where a label needs to be affixed to a wide range of surfaces.

Clarity of Transparency

Currently, the material offering the most clarity in terms of transparent films is PET or polyester. After this, it’s polypropylene, polystyrene and polyethylene. But of course, a high degree of transparency must ensure that both the label and its adhesive are equally transparent.

Most transparent adhesives are a minimum of 10 microns thick. They are usually applied in coats of around 20 grams per square metre. Even with adhesives, care needs to be taken to ensure that any backing used to protect the self-adhesive will not damage the adhesive when removed or if left to sit for long periods of time.

The removal of any self-adhesive label by a thief can be prevented by ensuring that the adhesive being used is able to resist the efforts by the thief to breach the adhesive bond. As well, any attempts to remove the label should be accompanied by some form of visual clue that the label has been tampered with. And although it may not be the most desirable measure, attempts to remove a label can also be made evident on the surface where the label is affixed.

Paper Finishes: Dispersion Coating

One very common surface enhancement of paper is called dispersion coating. Dispersion coating represents the most watery of available print coatings. Dispersion is defined as a mixture of two or more substances which are present in differing amounts. Several substances are present in dispersion coating. These include wax, defoamers, hydrosols, film formation aids, wetting agents and synthetic, water-soluble resins. As dispersion coating dries, its smooth surface is produced via the sticking together of water-soluble resins during the evaporation drying process.

The Dispersion Coating Process

Dispersion coating is usually applied after four colour or CYMK printing, where paper first passes through each of the four colours and then through a 5th coating unit. However, this coating can also be applied to paper via a system located inside the printing press itself, or via a dampening unit.

The drying of materials coated via the dispersion process occurs naturally. Due to the evaporation of hydrosols and the absorption of the coating itself, drying occurs very quickly. However, in instances where even quicker drying is required, heat can be applied. The inherent matte or glossy properties of paper will be enhanced by the dispersion coating process.

Why Is Dispersion Coating Ideal?

There are many advantages to dispersion coating beyond the facts that it is a very simple form of print finishing, is easy to apply and dries in a very short amount of time.

Any printed material, whether a series of inkjet labels, books or flyers can benefit from added protection when dispersion coating is applied. This protection shields printed materials from most forms of abrasion, as well as makes them slightly water-resistant. In addition, dispersion coating helps to preserve the colour of paper, preventing yellowing due to age. This is possible because the ink becomes bound with the coating once it’s been applied.

Dispersion coating also contains elements which give it an elastic quality. This quality is beneficial for printed documents which require further processing in the form of grooving, film embossing or creasing.

Which Products Are Best Suited To Dispersion Coating?

Dispersion coating can be used on virtually any product that will be printed and distributed. This includes brochures and inkjet labels. However, any items which may require anything to be written on them following printing such as business cards, postcards or flyers may benefit more from other coatings, as dispersion coating makes writing with a ballpoint pen or marker more difficult.

Paper which has gone through the dispersion coating process is also less likely to react well to printing or stamping. This is because the coating slows the absorption rate of ink. As a result, smudging can occur.

Two Potential Solutions

Where having materials coated with the dispersion print finish has been deemed a necessity and writing, printing or stamping will also need to occur, there are two potential solutions.

1) Depending on the intended use of the material being coated, it may be possible to alter both the combination and concentration of the coating so that it is spread onto the paper in a finer and thinner layer.

2) Another solution is to apply dispersion coating not over an entire product, but only in spots. This will allow for some areas of printed material to be stamped, written and printed on.

When considering dispersion coating, it’s a good idea to remember that different printing companies will have different set ups as far as dispersion coating units are concerned. Some coating units will be smaller in size than ink printing units, where others may be larger. However, the size of the coating unity should not affect coating quality or coverage.

Dispersion coating is both a very common and very popular form of print finishing. However, it isn’t the only kind. If there is some doubt as to whether dispersion coating is the ideal choice, an experienced printing professional can certainly provide further insight.

Which Print Coating Is Right For Your Materials – Aqueous, Varnish Or UV? Part I

When you need to add an element of creativity to your printed materials or want to ensure they are protected, do you know which options are available to you? Not choosing the right coating for the paper being printed on can result in a much different look and feel than you originally intended.

There are three main print coatings: aqueous, varnish and UV. Each coating type has its own sub-set of styles. Under the aqueous coating group are matte, pencil receptive, gloss and dry erase, to name a few. Varnish coatings are available in the opaque, matte, satin, gloss and strike-through matte varieties.

What’s the difference between Aqueous and Varnish Coatings?

The aqueous coating, as its name suggests, is water-based. The application of aqueous coating involves the use of a special press unit and a rubber blanket. Varnish coatings can be tinted and are applied in the same way that ink is; on a printing press.

Aqueous Coatings in Detail

An aqueous coating is less likely to turn yellow over time than a varnish. As well, aqueous coatings are used on inkjet labels and other materials which require protection from fingerprints and similar blemishes. Because aqueous coatings dry quickly, projects which utilise them take far less time to complete on professional presses.

One interesting aspect of the aqueous coating is that when applied, it can prevent metallic inks from tarnishing. This is because the aqueous coating seals ink onto paper via air drying. Although it may not occur for a number of years, the aqueous coating has been known to cause certain spot colours to change completely. Finally, paper which is under a certain text weight may wrinkle, curl or distort because of the coating’s water-based nature.

Popular Aqueous Coating Types

There are several popular types of aqueous coating. One is used as primer, and is aptly named primer aqueous. This coating is applied prior to any lamination, or on materials that tend not to be receptive to the application of ink.

Another is called gloss aqueous coating. This particular type is usually applied all over a material. When gloss aqueous coating is applied, it dries right away. This property makes gloss aqueous ideal for small projects that need to be completed quickly.

Pencil-receptive aqueous, as its name suggests causes the material being printed to more easily accept the transfer of pencil, laser and pen inks.

Satin, matte and soft touch aqueous each have their own special properties. Satin has a soft sheen and protects materials, where matte is resistant to scuffs. Soft touch has a luxurious texture and a completely matte surface.

Dry erase aqueous coating is an alternative to lamination with an added benefit: it transforms nearly any paper into a surface that can be written on with dry-erase implements.

Varnish Coatings in Detail

In addition, to be able to be printed like ink, varnish coatings offer the ability to be incorporated with the ink itself, which allows for the visual enhancement of printed materials. Incorporation with ink can be accomplished via two methods: dry trapping and wet trapping.

The dry trapping of varnish occurs when it is printed following the drying of the ink. This is accomplished by sending materials through the system for a second time. Wet trapping is the application of varnish at the same time as other inks are applied.

Paper Coating and Print Colour

You can easily tell uncoated paper from coated by looking at it. Uncoated paper will have a matte appearance and will have a bit of a rough feel to it. Coated paper will have a shimmer to its appearance and a smooth and slightly waxy feel. The differences between the two types of paper also make a significant difference to the way images and colour will appear once printed.

How Uncoated Paper Behaves with Ink

Uncoated paper is absorbent by nature. Therefore, any ink applied to this kind of paper will soak into it. When this happens, the dot gain effect occurs. Dot gain is referred to as a phenomenon whereby printed material looks darker than originally intended.

Dot gain can be identified by looking closely at a printed image or text. If the dots which make up the image or text appear fuzzy or smudged, then dot gain has occurred. Looking at the entire printed image or text, dot gain will affect the overall appearance by making it look less detailed than it should be.

It is not the colour, but the type of paper which causes dot gain to occur. However, the dot gain phenomenon can affect how printed colours look.

Why Paper Coating is Important

Paper coating becomes an important thing to consider when you need your printed items to have uniformity. For example, if you have a company logo, it is a representation of your brand. Everything about how a logo looks, from the fonts used to its colours and images, sends a message about your brand. For that message to be consistent, all of the elements of your logo must look the same on everything it’s placed on.

Coated paper is like a pane of glass; ink applied to its surface will tend to remain nearer to the surface. That will cause the final printed result to appear far more vibrant than that printed on uncoated paper, which is like a sponge, causing printed colours to be far less vibrant and duller.

Because the printed colour on uncoated paper can look far different from that printed on coated paper, some thought needs to be put into what kind of paper you are using. Your business cards may have a glossy finish, but if your stationery does not, this could cause a break in the visual uniformity of your logo.

Ways to Circumvent Colour Issues

One way that colour issues can be avoided is to add contrast to the image or text being printed. However, doing so can also negatively affect the outcome, and should be applied with caution.

Another way to avoid colour issues is to print several test images to ensure that colour levels are where they should be.

Finally, one reliable method is to choose Pantone brand colours. These colours are the standard reference for the print industry, allowing for an exact colour to be produced when an item is printed. However, caution needs to be taken here as well, because two types of Pantone colour exist: 185U for uncoated paper and 185C for coated paper.

What to Consider Before You Print

The paper types that your materials will be printed on should be as close to one another as possible regarding appearance and paper type. Otherwise, you may spend money on a large print job, only to find that each printed item appears to have been printed using completely different colours, even though this may not have been the case at all.

The best advice is to take lots of time to research the materials you plan to have your logo printed on. As well, speaking with your printing company is another good way to ensure that colours remain uniform across all of your printed materials.