How Do I Choose The Right Offset Ink For My Specific Printing Project?

Setting the Direction Based on the End Use of Printed Materials

 

1. Printing Newspapers and Periodicals:

 

Focus on "High Speed ​​+ Low Cost + No Smudge." Ordinary Oil-Based Newsprint Inks are the Core.

The core requirements for newspapers and periodicals are "printing large quantities in a short time, without getting readers' hands dirty." For example, daily newspapers are printed in the wee hours of the morning for early morning distribution, and single batches can potentially produce hundreds of thousands or even millions of copies. Inks must keep up with this "fast pace and low cost." Specifically, consider the following:

Three Key Reasons to Prefer Ordinary Oil-Based Newsprint Inks

Low Cost, No Cost for Large Volumes: This type of ink uses mineral oil as its primary solvent (approximately 50%-60%). Raw materials are readily available, and processing technology is mature. Unit prices are typically 30%-50% lower than thermosetting inks. For newspaper companies, printing one million copies can reduce the ink cost per copy to just a few cents, resulting in significant long-term savings. Furthermore, its tinting strength is perfectly matched to newsprint-newsprint has a rough surface and strong ink absorption. The pigment particles (approximately 5-10μm in diameter) of ordinary oil-based inks quickly embed themselves into the paper fibers, producing clear text without the need for high pigment concentrations, further reducing raw material costs.

 

Its excellent fluidity allows it to operate smoothly with high-speed printing presses: Newspaper presses typically run at speeds of 30,000-60,000 copies per hour, and ink must have excellent fluidity to ensure even transfer to the printing plate. Ordinary oil-based newsprint inks have a low viscosity (typically 200-500 cP), allowing them to spread quickly through the machine's inking roller system, eliminating the problem of uneven ink flow and broken lines. For example, on a web offset press printing daily newspapers, the entire process from ink tank to printing plate to paper takes only a few seconds. Low-viscosity oil-based inks ensure a consistent ink layer thickness across every sheet, preventing some text from being too thick and others from being too light. Drying speed is suitable for newsprint, preventing stains on hands: Newsprint absorbs ink well. When printed with standard oil-based ink, most of the solvent is absorbed by the paper fibers within 10-30 seconds. The remaining solvent evaporates quickly in the air, allowing the paper to dry without additional heating. By the time readers receive the newspaper, the ink is already dry and won't rub onto their fingers. Furthermore, when stacked (for example, in a pile), the ink from the lower layers won't stick to the back of the upper layers, preventing smearing.

Tips to Avoid: Don't Choose "Low-Quality Recycled Ink" for Cheaper Prices
Some small mills reprocess recycled waste ink. While this may offer a lower price per unit, it can be prone to problems: First, uneven pigment dispersion can cause "ink spots" in printed text, impacting the reading experience; second, the solvent can be low-purity and contain a high concentration of impurities, potentially clogging the machine's ink rollers, requiring downtime for cleaning and delaying the printing process; and third, the drying speed can be erratic, with some areas drying quickly and others slowly, significantly increasing the risk of smearing when stacked. It's recommended to choose ink from a reputable manufacturer and request a batch test report. Focus on ensuring the viscosity, drying time, and pigment content meet standards.

Special Case: Printing Periodicals with Color Inserts: Minor Ink Adjustments May Be Adapted
If a periodical includes a small number of color inserts (for example, a weekly food column featuring color illustrations), and the color saturation of pure, ordinary oil-based ink is insufficient, consider switching to "low-concentration color oil-based ink." This ink has a slightly higher pigment concentration than regular newsprint ink (but lower than heat-set ink), producing vibrant colors without significantly increasing costs. It also dries quickly enough to accommodate newsprint, preventing inserts from smudging.

 

2. Printing Brochures, Product Catalogs, and Magazine Covers: Striving for "Appearance + Texture," thermoset/soy-based glossy inks are the primary choice. Brochures and product catalogs rely on visual appeal to impress customers.

 

For example, cosmetics brochures should capture the glossy finish of skincare products, while home appliance catalogs should replicate the metallic texture of products. Magazine covers must be "bright and durable," so inks must meet standards in color, gloss, and texture. The specific application scenarios are:
1. Printing Brochures on Coated Paper/Matte Paper: Prioritize thermoset inks, balancing speed and appearance. Coated paper (smooth, coated surface) and matte paper (matte surface, delicate texture) are commonly used for this type of printing. Ordinary oil-based inks tend to dry slowly and smudge on these, while thermoset inks are a perfect match. They offer three key advantages:

Quick drying, no delays in binding: Thermoset inks contain "thermosetting resins." After printing, they pass through the machine's "heating tunnel" (approximately 120-160°C) for 10-20 seconds. It dries completely within seconds, eliminating the risk of smearing even on smooth coated paper. For example, printing 10,000 copies of a cosmetics brochure can be completed in the morning and folded and bound in the afternoon, eliminating the need to wait for the ink to dry naturally, significantly reducing production cycles.
High color reproduction, capable of accurately reproducing the original design: Thermosetting inks have a high pigment concentration (20%-30% higher than ordinary oil-based inks) and finer pigment particles (approximately 2-5μm in size). These pigments adhere evenly to the coated surface of coated paper, accurately reproducing the original design's colors. For example, the "cherry blossom pink" in the original design will not be tinted reddish or white when printed with thermosetting ink, and can even create a gradient effect. When printing metallic products, a varnish can be added to create a glossy finish, simulating the reflective effect of metal.
Abrasion-resistant, no ink bleeds when turning pages: Thermosetting inks form a tough film after drying, which resists rubbing the pages of the brochure. For example, home appliance catalogs are frequently flipped through by customers, and thermosetting inks ensure that product images won't fade even after being flipped through 100 times.

 

 For a more environmentally friendly and low-odor option: Choose soy-based glossy ink.

Many brands (especially those selling maternity and baby products and organic products) are now demanding "eco-friendly printing." Soy-based glossy ink is a good choice. Using soybean oil as its primary solvent (instead of traditional mineral oil), it offers significant advantages:

Low odor, suitable for close reading: Soybean oil is a plant extract and contains no volatile harmful gases (such as benzene). The resulting printed catalogs have a neutral, non-pungent odor even when sniffed closely, making them suitable for children's picture books and maternity and baby product catalogs, ensuring safe handling by both parents and children.

 

Rich colors and reusable: Soy-based glossy ink offers comparable color saturation to thermosetting inks, resulting in vibrant images. It is also biodegradable-once printed materials are discarded, the ink slowly degrades in the natural environment, minimizing environmental pollution. Soy-based ink also has good adhesion, creating a delicate matte texture when printed on matte paper. This makes it suitable for high-end, minimalist brochures (such as luxury catalogs). 3. Pay attention to detail: Choose matching inks based on process requirements.
If the album features hot stamping or embossing, choose a thermosetting ink that's compatible with hot stamping foil to prevent chemical reactions between the ink and the foil, which could cause the hot stamping to dissolve.

If the magazine cover needs to be sun-resistant (for example, for outdoor brochures), choose a thermosetting ink with added UV absorbers to prevent the cover's color from fading. Regular thermosetting inks may discolor after three months, while those with absorbers can last for 6-12 months.

If printing white text on dark paper (for example, printing a white product name on black cardstock), choose a high-opaque white ink. This type of white ink has a high titanium dioxide content (approximately 50%-60%), allowing it to completely cover dark paper. The printed white text is crisp, without a gray cast, and without the appearance of "black showing through the text."

 

3. Packaging Printing (Food Boxes, Cosmetics Boxes):

 

The Core is "Safety + Durability," and Compliant Inks are the Bottom Line.
For packaging that comes into direct contact with the product (e.g., biscuits in food boxes, cream in cosmetic boxes), or undergoes transportation and stacking, the ink must meet the requirements of "safety, non-toxicity, abrasion resistance, and corrosion resistance." The ink selection process for different packaging scenarios varies:

Food Packaging (biscuit boxes, milk cartons, snack bags): Strictly select "food contact-grade compliant inks."
Food safety is the bottom line, and the ink must comply with "food contact material standards." Specifically, please note the following:
First, check certifications to avoid the migration of harmful substances: Be sure to choose products that are FDA (U.S. Food and Drug Administration) certified or comply with the national standard GB 4806.11-2024 (Food Contact Inks). These inks have extremely low "migration" (the amount of harmful substances transferred from the ink to food), such as heavy metal content (lead, cadmium) ≤ 10mg/kg, which poses no risk to human health. For example, when printing the inner wall of a biscuit box, even if the biscuits come into direct contact with the ink, there is no need to worry about harmful substances leaching. Choose solvent-free/low-solvent inks to avoid odors that could affect food: Prioritize water-based food contact inks or UV-curable food contact inks. Water-based inks use water as a solvent and are virtually odorless, preventing food from imparting an "ink smell." UV inks contain no volatile solvents and leave no residual odor after drying, making them suitable for printing sealed food packaging (such as the outer pattern of milk cartons). Avoid using conventional oil-based inks, as their solvents may evaporate into the food, affecting the taste.

 

Pay attention to temperature resistance to ensure compatibility with food processing/storage scenarios. If the food will be heated (such as a microwave-safe lunch box), choose an ink rated for temperatures between 120-180°C to prevent melting or fading. If the food will be refrigerated (such as a yogurt container), the ink should be able to withstand temperatures as low as -18°C to prevent brittleness or ink loss.

 

Cosmetics/daily chemical packaging (cream bottle labels, shampoo boxes):

Choose inks that are "friction-resistant and chemical-resistant."
This type of packaging has two core requirements: First, the ink must not be rubbed off because it's frequently handled by consumers; second, the ink must not be corroded by chemicals in cosmetics (such as alcohol and essential oils). Key points for ink selection:

Friction-resistant: Choose inks with "abrasion-resistant agents." Regular inks printed on cosmetic boxes can rub off with repeated rubbing. Inks with added "polyamide abrasion-resistant agents" dry to a high-hardness film (a pencil hardness of 2H or higher) and resist scratching with fingernails. For example, shampoo boxes are often stored in bathrooms (a humid environment). Friction-resistant inks ensure the design won't rub off even if they get wet.

 

Chemical-resistant: Avoid inks that are easily soluble. The alcohol and essential oils in cosmetics can dissolve regular inks, blurring the design. Choose solvent-resistant inks (such as polyurethane inks). They resist rubbing against ingredients like alcohol and glycerin, preventing the ink from spreading even if cream accidentally gets rubbed onto the packaging.
Adding to the aesthetics: Choose inks that can create special effects: Cosmetics packaging often requires matte, pearlescent, or metallic finishes. Consider choosing matte inks (for a delicate matte texture), pearlescent inks (with added pearlescent powder for a shimmering effect), or metallic inks (for simulating gold or silver). These inks are not only aesthetically pleasing but also enhance the product's premium feel.

 

Transport packaging (express delivery boxes, product packaging):

Choose economical inks that are shatter-resistant and weather-resistant.
Transport packaging doesn't need to be aesthetically pleasing, but it must withstand the rigors of shipping. We recommend choosing standard oil-based packaging inks. These inks offer the following advantages:

Shock and impact resistance: The ink film is resilient, preventing it from cracking or fading even when the packaging is dropped or crushed.

Weather resistance: Withstands outdoor exposure to wind and rain. For example, if express delivery boxes are stacked outdoors, the ink will not be washed away by rain or faded by the sun.

Low cost: The unit price is 40%-60% lower than food contact inks and cosmetic packaging inks, making it suitable for printing large quantities of shipping packaging and keeping packaging costs low.

 

Ink Properties Corresponding to Project Requirements

 

First, consider "drying speed": Don't wait until the printed pages are piled together and smudged before you regret it. If you're using a high-speed press (e.g., printing over 30,000 copies per hour) or need to fold and bind the pages immediately after printing, choose a fast-drying ink. Heat-curable inks and UV-curable inks are both good choices. The former dries by heat, while the latter dries in seconds under ultraviolet light. If you're printing slowly and want to lay the finished product out to dry, ordinary oil-based inks will suffice.

 

Next, consider "color performance": To ensure the printed color matches the design, pay attention to "color density and color fastness." For example, if you're printing a brand logo and require precise color, choose an ink with "high color density" to achieve rich colors with fewer print passes. If you're printing outdoor posters, choose an ink with "good light fastness" to prevent fading after a few months of exposure. When printing on dark paper (e.g., white text on black cardstock), use a white ink with "high opacity," otherwise the text will turn gray and become difficult to read.

 

Also consider Environmental protection requirements: Clients are increasingly concerned about whether printing is green. If environmental protection is a priority, prioritize soy inks and water-based offset inks. Soy inks are made from plant extracts, have a low odor, and are easily biodegradable. Water-based inks contain no volatile harmful gases and are suitable for food packaging and children's books. Also, be sure to request environmental testing reports from ink manufacturers to avoid compliance pitfalls.

 

Overall Cost

 

First, consider the "volume": While high-concentration inks may be more expensive per unit, they require less ink to print the same area. For example, while regular ink requires three coats to achieve full color, high-concentration inks only require two, saving ink and machine run time.

Next, consider "subsequent costs": For example, choosing UV inks, while expensive, dries quickly, eliminating the need for drying space and heating equipment. Choosing rubbing-resistant inks reduces rework due to smearing and discoloration, ultimately reducing waste costs.

Also consider "compatibility": Avoid inks that are incompatible with your machine and paper. For example, using thermosetting inks on a slow-speed machine will hinder the heating function, resulting in slow drying and increased sticking. Using regular inks on plastic paper will result in poor adhesion and lead to rework, ultimately wasting money. It's best to have the manufacturer send you a sample first, test print it on your machine and paper, and only purchase in bulk if you find it satisfactory.