What is the difference between UV Varnishing, varnishing and laminating?
Clients often become confused with the various finishes that can be applied to printing materials. Not knowing the right one can cause problems so its important that when ordering that you tell your printer exactly what you require.
So, what is the difference between UV Varnishing, varnishing and laminating? There are several kinds of varnish that can be applied to printing, but all share some common characteristics. Here are a a few basic pointers.
- A varnish increases colour absorption
- They speed up the drying process.
- The varnish helps to prevent the ink from rubbing off when the paper is subjected to handling.
- Varnishes are used most frequently and succesfully on coated papers.
- Laminates are best for protection
A machine seal is a basic, and virtually invisible coating applied as part of the printing process or offline after the project leaves the press. It does not affect the appearance of the job, but as it seals the ink under a protective coat, the printer need not wait so long for the job to be dry enough to handle. It is often used when producing fast turnaround printing such as leaflets on matt and satin papers, as inks dry more slowly on these materials. Different coatings are available in different finishes, tints, textures and thicknesses, which may be used to adjust the level of protection or achieve different visual effects. Areas that are heavily covered with black ink or other dark colours often receive a protective coating to guard against fingerprints, which stand out against a dark background. Coatings are also used on magazine and report covers and on other publications that are subject to rough or frequent handling.
Liquid coatings are by far the most common way to protect print publications. They provide light to medium protection at a relatively low cost. Three major types of coatings are used:
A varnish is a liquid coating applied to a printed surface. It is also referred to as coating or sealing. It is noramlly used to prevent rubbing or scuffing and ofteen used on coated stock. Varnish or print varnish is a clear coating that can be processed like an ink in (offset) presses. It has a similar composition to ink, but lacks any color pigment There are two forms
- Varnish: A clear liquid applied to printed surfaces for looks and protection.
- UV coating: Liquid laminate bonded and cured with ultraviolet light. Environmentally friendly.
Ultraviolet light. It can be a gloss or a matt coating. It can be used as a spot covering to accent a particular image on the sheet or as an overall flood coating. UV coating gives more protection and sheen than either varnish or aqueous coating. Since it is cured with light and not heat, no solvents enter the atmosphere. However, it is more difficult to recycle than the other coatings. UV coating is applied as a separate finishing operation as a flood coating or (applied by screen printing) as a spot coating. Keep in mind that this thick coating may crack when scored or folded.
Varnish coating are available in gloss, satin or matt finishes, with or without tints. Varnishes offer a relatively low degree of protection compared to other coatings and laminates, but they are used widely, thanks to their low cost, flexibility and ease of application. Varnishes are applied just like an ink, using one of the units on the press. Varnish can either be flooded across the entire sheet or spot applied precisely where desired, to add extra gloss to photos, for example, or to protect black backgrounds. Although varnishes must be handled carefully to prevent the release of harmful volatile organic compounds into the atmosphere, when dry they are odorless and inert.
Aqueous coating is more environmentally friendly than UV coating because it is water based. It has better hold-out than varnish (it does not seep into the press sheet) and does not crack or scuff easily. Aqueous does, however, cost twice as much as varnish. Since it is applied by an aqueous coating tower at the delivery end of the press, one can only lay down a flood aqueous coating, not a localized “spot” aqueous coating. Aqueous comes in gloss, dull, and satin. Like varnishes, aqueous coatings are applied inline on press, but they are shinier and smoother than varnish, have higher abrasion and rub resistance, are less likely to yellow and are more environmentally friendly. Aqueous coatings dry faster than varnishes too, which means faster turnaround times on the press.
Available in gloss or matt finishes, water based coatings offer other advantages as well. Because they seal the ink from the air, they can help prevent metallic inks from tarnishing. Specially formulated aqueous coatings can be written on with a number two pencil, or overprinted using a laser jet printer, a key consideration in mass mail projects.
Aqueous coatings and UV coatings as well are also susceptible to chemical burning. In a very small percentage of projects, for reasons not fully understood, certain reds, blues and yellows, such as reflex blue, rhodamine violet and purple and pms warm red, have been known to change color, bleed or burn out. Heat, exposure to light, and the passage of time can all contribute to the problem of these fugitive colors, which may change at any point from immediately after the job leaves the press to months or years later. Light tints of colors, made using a 25% screen or less, are especially prone to burning.
To help combat the problem, ink companies now offer more stable, substitute inks that are close in color to ones that tend to burn, and these inks are often used to print light tints or bright colors. Even so, burning can still occur and dramatically affect the look of the project.
Laminate is a thin transparent plastic sheet or coating that is usually applied to covers, post cards, etc. providing protection against liquid and heavy use, and usually accents existing colour, giving a high gloss effect. Laminates come in two types: film and liquid, and can have a gloss or matt finish. As their name suggests, in one case a clear plastic film is laid down over the sheet of paper, and in the other case a clear liquid is spread over the sheet and dries (or cures) like a varnish. Laminates protect the sheet from water and are therefore good for coating items like menus and book covers. Laminates are slow to apply and costly but provide a strong, washable surface. They are the superior choice for protecting covers.
Which varnish is right for your job?
Laminates offer the greatest protection and are unbeatable in a variety of applications, from maps to the menus, business cards to magazines. But with their greater weight, time, complexity and expense, laminates are typically not suited for projects with extremely large press runs, limited life spans or short deadlines. If laminates are used, there may be more than one way to achieve the desired results. Combining a laminate with a heavier paper stock produces a thicker finish at a lower cost.
If you can’t decide, remember that the two types of finishes can be used together. A spot matte UV coating, for example, could be applied over a gloss laminate. If the project will be laminated, make sure to factor in additional time and often, additional weight if mailing.
How to use coated paper
No matter what coating you use, the results will look always look better on coated paper. This is because of the the hard, nonporous surface of the stock holds the liquid coating or film on the top of the paper, without allowing it to run into in to the surface of uncoated stocks. This superior holdout helps ensure that the protective finish will go on smoothly. The smoother the surface, the better the quality.