When you’re creating a printed product, the ink on the page is just the beginning. To truly make your brochures, packaging, or business cards stand out, you need a finish.
This final step not only protects the ink but also makes your print materials feel professional.
In the printing world, this standardized finish is known as aqueous coating.
This guide will walk you through everything you need to know, from what aqueous coating is to which finish is perfect for your next project.
What is Aqueous Coating?
Aqueous coating (often called AQ coating) is a clear, fast-drying, water-based overprint varnish used in the printing industry.
For the last 30 years, it has become the “default” coating for high-end commercial and packaging printing, largely replacing traditional press varnishes.
Aqueous coating like the clear coat on a car’s paint job. The original paint (the ink) looks vibrant, but the clear coat adds an extra layer of shine (or a sophisticated matte look) and forms a protective, flexible barrier.
This coating dries fast, protects the color underneath from everyday scratches, scuffs, and fingerprints, and gives the final product a smooth, premium feel.
It’s applied in-line on the printing press, meaning it’s put on the paper right after the inks.
The “aqueous” part of its name comes from the fact that it’s water-based as over 50% of its content is water.
The Composition of AQ Coating
As it’s water-based, the coating itself is a complex formula. Most aqueous coatings include:
- Polymeric Resin: This forms the base of the formula, often acrylic or polyester, and creates the protective film and gloss.
- Wax and/or Silicone: These additives provide crucial rub resistance, to prevent scuffing, and slipperiness.
- Surfactants: These chemicals help the coating flow smoothly and level out for an even finish.
- Additives: A variety of other materials are added in small amounts to enhance properties, such as defoamers to prevent bubbles, and optical brighteners.
The coating “dries” when the water and other volatile components are removed through a combination of heat, forced air, and absorption into the paper itself, leaving behind the protective resin film.
The Benefits of Aqueous Coating (Why It Matters)
Aqueous coating is the industry standard because it provides a perfect balance of benefits for both the printer and the customer. It delivers a superior product efficiently and responsibly, ensuring a professional finish.
1. Durability and Protection
This is the primary reason for any coating.
Aqueous coating offers excellent rub and scuff resistance. It protects your printed pieces from the scratches, smudges, and fingerprints that happen during shipping, handling, and everyday use.
It also helps prevent the ink from “offsetting” (transferring from one sheet to another) when the sheets are stacked.
2. Speed and Efficiency
Because AQ coating is applied in-line and dries rapidly (with the help of infrared dryers and air knives on the press), jobs are finished much faster.
- No Spray Powder: It reduces or completely eliminates the need for the anti-offset spray powder that is typically used with traditional varnishes. This powder leaves a gritty, sandy feel, whereas an AQ-coated piece feels smooth and clean.
- Faster Handling: Sheets are dry and ready for the next step (like cutting or folding) almost immediately. This means printers can run full loads without racking, and you get your finished product faster.
3. Superior Aesthetics
Aqueous coating gives your product a much more professional and tactile feel than uncoated paper.
- Non-Yellowing: Unlike older, oil-based varnishes, aqueous coating is non-yellowing. A white paper will stay bright white, and your brand colors will remain true over time.
- Smooth Finish: The lack of spray powder means the final piece feels smooth and premium to the touch.
4. Eco-Friendly and Safe
As a water-based product, aqueous coating is significantly more environmentally friendly than UV or varnish alternatives. It is non-toxic and doesn’t release the same level of volatile organic compounds (VOCs).
Most AQ-coated paper is fully recyclable, making it an excellent choice for eco-conscious brands. It’s also non-flammable.
5. Cost-Effective
Aqueous coating offers a high-end, durable finish without the significant price jump associated with UV coating or plastic lamination.
It provides one of the best value-for-money propositions in print finishing.
Types of Aqueous Coating Finishes
Aqueous coating isn’t a one-size-fits-all solution. It comes in a variety of finishes, allowing you to achieve the exact look and feel your design calls for.
Gloss Aqueous Coating
A gloss aqueous coating provides a high-shine, reflective finish that makes colors appear vibrant and deep.
It’s excellent for grabbing attention and is commonly used on brochures, catalog covers, and flyers where you want the images to “pop.”
Matte Aqueous Coating
A matte aqueous coating does the opposite: it provides a non-reflective, satin-smooth finish. This is used to achieve a subtle, sophisticated, and high-end look. It diffuses light, which can make text easier to read.
Matte is a popular choice for luxury brands, art-focused lookbooks, and any design that prioritizes an understated, elegant feel.
Aqueous Coating vs. Other Finishes
It’s easy to get confused between the different types of coatings and finishes.
Here’s a quick comparison of how aqueous coating stacks up against the other common options.
Aqueous Coating vs. Press Varnish
This is the older, oil-based alternative. Aqueous coating is superior in almost every way.
Varnish is slower to dry, more likely to yellow over time, and offers less gloss and less protection than AQ.
Most modern printers use aqueous coating as their standard instead of varnish.
Aqueous Coating vs. UV Coating
This is a very common comparison.
UV coating is a liquid that is cured almost instantly with ultraviolet light.
- The Look: UV coating provides a much higher gloss or a “wet look” that is significantly shinier than gloss AQ.
- Protection: UV is thicker and more durable, offering better solvent and chemical resistance.
- Flexibility: UV coating can crack when folded or scored, whereas aqueous coating is more flexible.
- Cost & Environment: UV coating is typically more expensive and less environmentally friendly than aqueous coating.
Aqueous Coating vs. Lamination
Lamination isn’t a liquid coating at all.
Instead, it’s a thin plastic film that is bonded to the paper with heat and pressure.
- Protection: Lamination is the most durable option. It is often waterproof, tear-resistant, and provides maximum protection.
- Feel: Lamination adds a noticeable thickness and a distinct “plastic” feel to the paper.
- Cost & Environment: Lamination can be costly and is not recyclable.
How Do the Coatings Compare?
Here’s a quick overview of the different coating types and their advantages and disadvantages when it comes choosing the right one for your products:
| Feature | Aqueous Coating | Lamination | UV Coating |
|---|---|---|---|
| Finish | Gloss, Matte | Gloss, Matte, Soft-Touch | Highest Gloss (“Wet Look”) |
| Protection | Good (Rub/Scuff) | Maximum (Waterproof, Tear) | Excellent (Chemical/Solvent) |
| How It Works | Water-based liquid, dried by IR/Air | Plastic film, bonded by heat | Liquid, cured by UV light |
| Eco-Friendly | Yes (Water-based, Recyclable) | No (Plastic film) | Moderate |
| Cost | $ (Cost-effective) | $$ (Mid-range) | $$$ (Highest) |
| Folding | Yes, very flexible | Never cracks or tears, thus perfect for folded items or book covers | Can crack if not scored well |
How Is AQ Coating Applied and Measured?
To understand the technical side of the aqueous coating and why it’s useful, it helps to understand the science behind the scenes.
Printers have to master several technical variables to achieve a perfect finish every time.
The Application Process
In modern aqueous coating printing, the coating is applied using a tower coater, which is an additional unit at the end of the press.
The coating is transferred to the paper using a series of rollers and a blanket. It’s almost always applied as a flood coating, which means the entire sheet is covered from edge to edge.
The Drying Process
Drying equipment is critical and the press uses a combination of heat and air to dry the coating rapidly.
- Heat: Short to medium wave infrared (IR) lamps are used to speed up evaporation.
- Air Flow: Air knives (tubes with slots) aim forced, high-velocity air onto the sheets. Printers often emphasize maximum air flow over high heat, as water evaporates best when in contact with low-humidity air.
- Temperature: An ideal load temperature is about 95°F (35°C). If the paper gets too hot, the coating can soften and cause sheets to stick together (called “blocking”).
Key Properties and How They Are Measured
Printers measure coating properties to ensure consistency:
- Gloss: This is measured with a gloss meter at a 60-degree angle. A higher stock gloss (e.g., on coated paper) will result in a higher finished gloss.
- Rub Resistance: This is the ability to withstand scratching and scuffing. It’s measured using a Sutherland Rub Tester, which rubs a weighted test strip over the printed piece for a set number of cycles.
- Slipperiness (Coefficient of Friction – COF): This measures the friction between two surfaces, often with a Slide Angle Tester. This is a trade-off: an ultra-slippery coating is great for rub resistance but can cause problems in finishing or gluing.
- Viscosity: This is the coating’s thickness or resistance to flow, and it’s the most important variable a press operator controls. It’s measured with a #3 Zahn Cup (a small cup with a hole) by timing how many seconds it takes for the coating to flow out.
Pro Tips for Design and Finishing Considerations
Aqueous coating is great, but it’s not universally compatible with every other process.
Keeping these limitations in mind during the design phase will save you headaches later.
- Heavier Paper is Better: While aqueous coating on paper (or aqueous coating paper) works, it’s best on paper stocks of 80lb text or heavier. Because the coating is water-based, very thin paper (like 60lb or 70lb) can warp, wrinkle, or curl from the moisture and heat.
- Leave Glue Flaps Bare: Aqueous coating (especially with wax additives) can prevent some cold-set adhesives from sticking. If your piece needs to be glued (like a pocket folder or custom box), you must design a “knockout,” a small, uncoated area, for the glue flap to adhere properly.
- You Can’t Write on Most AQ: Pens, pencils, and water-based inkjet printers (like your desktop printer) will not work well on a standard aqueous coating. The ink will smudge or fail to absorb. If you need a “writeable” area, it must be left uncoated.
- Laser Printing is a No: Most aqueous coatings resist re-melting in a laser printer, but the toner will not absorb and will likely flake off. This is also a consideration for aqueous coating digital printing, where compatibility must be checked.
Using Aqueous Coating with Special Finishes
Aqueous coating also works as a great partner for other high-end finishes.
- Foil Stamping: Many aqueous coatings are “foil-stampable,” allowing you to add a metallic foil design on top of the coated sheet.
- UV Coating Primer: One of the best uses of AQ is as a primer for spot UV. You can apply a flood matte aqueous coating over the whole sheet and then apply a high-gloss spot UV only on specific elements (like a logo or photo). The matte/gloss contrast is a powerful and popular effect.
What’s the Right Aqueous Coating for Your Project?
With all this information, the choice becomes simple. It’s all about matching the finish to your product’s goal.
- High-Impact Marketing: Use gloss coating for print marketing materials such as brochures, flyers or posters. It makes your colors and photos pop, grabs attention, and is durable enough for handouts.
- Subtle High-End Look: Use matte coating for catalogs, lookbooks, art prints. It exudes sophistication, reduces glare, and enhances readability.
- Premium, Tactile Experience: Use soft touch coating for business cards or luxury packaging. The velvety, unique feel makes an immediate, high-end impression that people won’t forget.
- Great All-Arounder: For magazines, corporate reports or mailers, you should use satin coating. It gives you the best of both worlds: good color vibrancy, high scuff resistance, and a quality feel without the high shine of gloss.
Why Choose ChilliPrinting for Your Coated Prints?
ChilliPrinting is an online printing service specializing in transforming your digital designs into stunning physical products for organizations and individuals across the US.
We handle the technical details so you can focus on your message.
- Expertise in Every Finish: From high-impact gloss to luxurious soft-touch, we have the technology and experience to apply the perfect aqueous coating for your project.
- Superior Quality: We’ve standardized aqueous coating on our most popular products because it delivers a more durable and professional result than uncoated or varnished alternatives.
- Fast Turnarounds: Our in-line coating systems mean your job is finished, dried, and ready for shipping faster, helping you meet every deadline without compromising on quality.
- Eco-Friendly Commitment: We are proud to use water-based aqueous coatings as our standard. It’s a high-quality, non-toxic, and recyclable option that’s better for you and the planet.
