Quick…what is a Flood UV? What is a spot varnish? Give up? Read on…
This Know More aims at understanding coatings. In the printing world, the word “coating” can mean two things.
Coated paper: Paper comes in basically three flavors:
- Synthetic paper: This made from plastic, resin, stone, latex, etc. It can look like anything from white paper to alligator skin to brass dust.
- Uncoated paper: This is made from wood pulp. It is usually white…sometimes “natural” (tan). It is fairly “vanilla”. This is the paper you see on letterhead, envelopes, the pages of most novels, the back of most travel post cards.
- …and Coated paper: Coated papers are made by applying a thin layer of clay to uncoated paper. When it dries (at the paper mill) you end up with a Matte Coated sheet. Polish it (at the paper mill) and it gets glossier going from Matte to Dull to Gloss to High Gloss.
Coated paper is NOT what we are talking about here
While coated paper has a “coating”, this is not what I am addressing in this Know More session. What I want to discuss is a coating that goes onto the paper after it is inked. This is usually as a clear finish. So, this is the second definition of “coating” and it is also known as a “flood” or “spot (varnish)”.
These coatings come in three flavors:
- Varnish: A resin based clear coating very similar to a varnish you put on wood.
- Aqueous: A water based clear coating very similar to a floor wax
- UV: Stands for “ultra violet” as it is cured using an ultra violet light source. This coating does NOT offer protection from UV (sun) rays!!
All are available in many degrees of reflection/finishes (matte through gloss). These coatings are usually ONLY applied to a coated sheet as applying them to a synthetic sheet may not be conducive to the sheet’s finish. Using these on an uncoated sheet would simply allow the sheet to drink in the liquid coating yielding no effect at all (or a very weird and unpredictable effect).
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These finishes/coatings are used with these objectives in mind:
1) To offer scratch protection to the sheet: From pocket folders to business cards to post cards…some projects need an added protection so they don’t get scuffed up. These finishes offer a higher degree of scuff resistance as they are applied over the ink.
2) They offer grease protection to the sheet: From fingerprints and coffee spills this helps the product look its best.
3) They are used for effect…to dull down or shine up an image, a photo, a headline, etc.
4) They “even out” the characteristics of the normal reflections of paper AND ink applications.
Here are some quick definitions and thoughts:
Note that ALL inks contain a degree of their own shine. Thus, a coated sheet that is considered to have a MATTE finish and gets a heavy saturation of ink on press, could dry with large areas having a sheen to them. These sheens are specific to the amount of ink that area received. If it is a large area (a matte coated sheet with a heavy saturation of black ink on the cover) the sheet will ALMOST look like a gloss coated sheet. Adding a dull flood over this will make the project look uniformly matte again.
Note that adding a gloss flood to a matte coated sheet will NOT make it shiny! However, adding a dull flood to a gloss sheet will, indeed, dull it down a bit.
While these coatings are all water and fingerprint resistant, all will break down if exposed to water. These are not plastics or laminates…they are only finishes. Just like a wet glass left on your desk top will leave a ring in the varnish, so will water (etc) effect these finishes.
Adding ANY of these coatings to a sheet will darken all the colors underneath the finish. Because of this our color proofing system is NOT ACCURATE to the finished piece if a varnish, aqueous or UV coating is applied. ALSO keep in mind that crossovers, plus-cover books, etc that have only certain areas of the project coated can not possibly match the colors in other parts of the project.
FLOOD: This means you are “flooding” the sheet. From edge to edge it’s like waxing the entire floor!
SPOT: Only specific portions of the sheet get a coating. Usually a title, a photo, etc. Often this is used to add a little bit of pop to the image as it offers a contrast between other areas on the project.
DRY TRAP: This means the coating is applied after the ink and/or another coating is dry. This allows for a very clean edge between two applications.
WET TRAP: The coating is applied on top of or up against another while all surfaces are still wet. Often this is more economical but is not always as “clean”.
In order to unclutter the mix, here is a table that covers MOST of the things we all need to consider when setting up a project that will require coating:
|Available on these presses –>||29” 8 Color||29” 8 Color
40” 8 Color
40” 10 Color
|This is applied using a standalone unit. It will only work with a sheet that is 20” wide (max). As such it “works” with all our presses including the digital offset press.|
|Finishes –>||High Gloss
|Advantages –>||Dries immediately and allows the project to be worked right away, even though the ink beneath the coating is still wet.
|Can be used as a spot or a flood.
When used along side of other finishes, can offer quite a striking contrast in shine.
|Dries immediately and allows the project to be worked right away, even though the ink beneath the coating is still wet.
Very tough finish…probably the toughest of all three.
Very shiny…a gloss UV coating is very obviously gloss!
|Limitations –>||Can only be used as a flood…there is no such thing as a spot aqueous.
Only available on our 29” press so impositions of larger projects are limited with this application.
|Takes longer to dry.||This is also offered as a spot application but we must outsource this sort of work as a spot UV is not available at our facility.
Only works with thicker (cover) stocks. Will not work with text weights.
To help you see how all this works, I have a VERY NICE SWATCH BOOK
that illustrates all these finishes and combinations.
Please contact me so I can send you a free copy!
It is easy to navigate and allows you to see how your project will respond to these applications.
That’s about it! Thanks so much! Please contact me if you have any questions or ideas. I am here to help you with your print communication and marketing needs!
Questions? Please email me at DRickman @ ColoradoPrinting.com or call me at 970-250-6749