OVERPRINT VARNISH INFORMATION FACT SHEET
OVERPRINT VARNISH TYPES
High Gloss Overprint Varnish is a non-yellowing, high gloss, quick setting varnish. This varnish is usually waxfree and can be UV, aqueous coated and foil stamped. High Gloss Overprint Varnish will provide a good protection barrier and adequate run and scuff resistance.
*Good Rub Resistance
Dull/Matte Overprint Varnish is an excellent tool for "matting" areas of a printed piece to give contrast. This varnish is usually formulated with waxes and has good rub and scuff properties. It is not a heat resistant product and cannot be UV coated or foil stamped.
*Excellent Matte Qualities
*Good Rub Resistance
Hard Surface Overprint varnish is designed for ultimate protection. It is formulated with a high percentage of waxes and drying agents to give maximium rub and scuff resistance. It is also an extremely fast setting varnish. The purpose for this varnish is for protection and not for high gloss effects. This is a non-imprintable product and cannot be UV coated or foil stamped.
*Tough Rub Resistance
APPLICATION OF OVERPRINT VARNISH
Oil based varnishes can be seen as an unpigmented offset ink. They are much the same and will handle in the same way on press. An average film thickness is usually enough to achieve your desired effect. With more varnish, heavier ink film, effects can be enhanced. Too much varnish applied can lead to blocking and offsetting. In the other direction starving a varnish, a film thickness too thin, can lead to loss of desired effect. Also starving a varnish will usually cause a build in tack and thus begin to pull wet ink which will contaminate the varnish and begin tinting the stock.
All overprints can usually be applied in-line, wet on wet, or off-line, wet on dry. These varnishes are constructed with low tacks to provide good trap over wet inks and to set fast to minimize absorption. Each method of applying varnish has its advantages and disadvantages. Wet on wet varnishing, in-line method, is cost effective and allows for less passes through the press. The only disadvantage is that wet on wet will not provide as great a gloss or dull effect as off-line varnishing. Wey on dry, off-line varnishing, is not cost effective in some cases and provides more passes through the press. Off-line varnishing will provide greater effects of gloss or dullness. Anytime a wet ink is placed over another wet ink the absorption factor is greater. This causes gloss varnish to appear less glossy and dull varnish to appear less dull. This is only in comparison to off-line varnishing. Wet on dry ink provides a hard, dry and smooth surface for varnish and enhances the effects of gloss or dullness.
Varnish can be applied in two formats, spot varnishing or flood varnishing. Spot varnishing refers to varnish only being applied to specific areas on a sheet. This is to give visual effects of contrast between areas that are varnished, gloss or dull, to areas that are not varnished. Or by combing gloss and dull, as spot varnish, to achieve even greater effect of contrast. Flood varnishing refers to completely varnishing a full sheet. This is a full covering of the sheet, with gloss or dull varnish, to add effect and provide protection to the sheet. Flood varnishing is best achieved when water is not used, or as little as possible is used to apply varnish. We refer to this as type of varnish method as dry varnishing. Without the introduction of water two important factors are gained. Without water, gloss or dull varnish, will achieve a greater gloss or dullness effect and will dry faster. Anytime extra water, moisture, can be left out of the equation the varnish will set faster and further finishing of the sheet can proceed in a shorter period of time.
All varnishes may be double hit to heighten the effects of gloos or dull. It is best achieved by double hitting varnish dry, off-line.
EFFECTS ON STOCKS
Any effect or protective coating you intend to create with varnish will be strongly influenced by choice of stock. Coated stocks, with smooth surfaces and excellent holdout, will yield the best varnish protection and visual effects. Uncoated stocks, with rougher surfaces and greater absorption, will not yield best visual effects, but still will provide some protection.
You can apply varnish to most any type of stock, coated, uncoated, matte, synthetic and cast coated. Each will have varying degrees of effect and protective capabilities. Examples:
Cast coated stocks applied with varnish will provide great protection, but applying a gloss varnish to a cast coated stock will usually "kill" the gloss effect of the stock. Dull varnish will give great contrast on cast costed stocks from the sheen of the stock to the areas that are dull varnished. Gloss and Hard Surface varnishes are best for protection.
Matte stocks can be applied with all types of varnish without any inherent problems. You can achieve great contrast and add protection to the job.
Gloss stocks can be applied with all types of varnish without any inherent problems. Gloss varnish will provide extra "pop" in gloss effect and protection. Adding dull varnish will provide matting effects and contrast.
Uncoated stocks offer a few more issues. Due to their nature, rough surfaces and high absorption, uncaoted stocks will not achieve great contrast when adding any varnish. Some uncoated stocks have better holdout than others and may provide different levels of contrast. Gloss varnish or hard surafce varnish will provide good protection to uncoated stocks. Dull varnish will provid little visual effect or protection to uncoated stocks. Hard Surface is the optimum choice for uncoated stocks.
Synthetic stocks can be varnished. We suggest that anytime you have a synthetic stock to varnish, send samples to your ink maker for proper testing. Special varnish should be used on these types of stocks and not the standard gloss or dull product.
EFFECTS OF VARNISH
Different types of stocks will react in different ways when applied with varnish. Each stock has its own characteristics, roughness, smoothness, absorption rates, pits and valleys. Varnish in turn will look, feel, protect and provide visual effects dependent upon the stock it is printed.
Varnish is a sealer that overprints ink and paper, helping to protect them from being scratched and scuffed and to provide visual effect. Gloss varnish will create a surface that appears smoother. Images will appear sharper because light reflected through clear varnish film travels to the viewer's eye with minimal diffusion. Ink covergae can affect gloss. Heavy ink coverage, four color build area of a sheet or heavy solid, provides a smoother surface and thus more reflectance than a screened area and will appear glossier or duller. Dull varnish imparts a velvety texture which scatters and diffuses light to give a matte look making images appear softer. This is achieved by platelet like particles in dull varnish that migrate to the surface and stand upright when varnish is dried. This is the reason that dull varnish will "mar" with relative ease. Dull varnish is a good protector. It provides good slip and rub resistance, but does have its limitations.
The application of gloss varnish can effect the ink color over which it is printed. Varnish may alter the appearance of the ink to look cleaner and brighter, add crispness to colors and saturation.
WHEN TO USE VARNISH
Varnish should be used anytime one wants contrast effects or protection for specific jobs. It is advantageous to use varnish for jobs showing a lack of drying or rub resistance as a protective coating for prints on matte coated stocks to prevent scuffing. On any job that the end use is to be handled often such as pocket folders, direct mail pieces, rack cards, brochures, covers for reports, books. This will help with fingerprinting. It is also best to varnish metallic inks that have heavy coverage on jobs. The metallic pigments in these inks act in the same way dull varnish does. Platelet like particles rise to the surface to provide reflectance and thus will easily mar. A varnish will help protect these inks.