Whether you’re running water-based or UV/LED inks, heat and humidity have a direct effect on performance, from ink adhesion to substrate handling. Below, we dive into three key challenges that surface in the summer months—and our expert’s recommendations to help you beat the heat.

Humidity Hazards in Ink Transfer and Adhesion

There are two ways that humidity can disrupt your print performance. The obvious one is muggy conditions in shops with no climate control. But even if you’re beating the heat inside with air conditioning and de-humidifiers, as you bring in your rolls of material from delivery trucks outside and place them on your shop floor, you may be facing some condensation issues—especially if those materials are placed directly on press without having time to adjust to the new ambient temperature.

No matter how humidity is being introduced to your print process, it can lead to a decrease in the surface energy of your substrate leading to poor ink adhesion, mottling, or other ink laydown issues. Avoid quality inconsistencies and material waste due to humidity by taking some precautionary steps in your operations. 

What to do

If possible, aim to keep your pressroom conditions at 45–55% relative humidity and under 75°F.

Don’t leave rolls on trucks or in loading bays during peak heat.

Allow substrates time to cool after being delivered.

Test your substrate with dyne pens before press runs and utilize a corona treater when needed.

Summer-Proof Your Storage

The pressroom isn’t the only area that suffers in the summer. Substrates stored in hot, unventilated warehouses can degrade quickly. Pressure-sensitive label rolls exposed to excessive heat may experience adhesive bleed, edge ooze, or even roll telescoping. Shrink films stored above 90°F can warp and distort from the heat, affecting registration and print quality.

What to do

Store sensitive substrates below 80°F in low-humidity rooms.

Rotate inventory using FIFO—older stock will degrade faster in hot conditions.

Store label stock vertically when possible to reduce adhesive pressure on roll edges.

Consider investing in insulated storage or HVAC upgrades for warehouse spaces.

Beat the Heat with UV/LED Curing

Traditional mercury vapor curing lamps emit a lot of infrared heat, raising web temperatures significantly. This only exacerbates heat-related issues during the summer months, which is especially problematic for label stocks, where heat can soften pressure-sensitive adhesives, or prematurely distort shrink films.

By contrast, UV and LED technologies cure at much lower web temperatures, helping printers maintain substrate integrity even on the hottest days. Beyond just label compatibility, UV/LED systems also reduce the need for heavy ventilation and climate control, lowering air conditioning costs and reducing pressroom energy consumption.

What to do

If you’re already considering making the switch to UV/LED curing technology, this could be an added benefit. Ask your press manufacturer or lamp supplier for more detailed cost savings projections to understand your potential ROI.

Summer Success with Smart Printing Practices

While you can’t change the weather, you can adapt your processes to maintain quality and performance all summer long. By understanding how heat and humidity affect your substrates, inks, and equipment—and by investing in temperature-friendly technology like UV/LED curing systems—you’ll be better equipped to handle seasonal variability without sacrificing consistency.

Zeller+Gmelin has decades of experience formulating high-performance UV and LED ink systems specifically designed for label and packaging printers who demand stability, efficiency, and brilliant results—even in the toughest pressroom conditions. Whether you’re facing ink transfer challenges or planning a shift to low-temperature curing, our team is here to help.

Contact your local Zeller+Gmelin representative to learn how our UV/LED ink solutions can support your operation this summer—and beyond.

The post Surviving Summer in the Pressroom: How to Protect Ink Adhesion and Label Quality first appeared on Zeller + Gmelin.

How do UV and UV LED offset printing inks work?

UV and UV LED offset printing inks contain photoinitiators that react when exposed to different wavelengths of light, instantly setting and adhering to the printing substrate. Both use ultraviolet light to cure the ink or coating onto the substrate, rather than drying by evaporation like oil-based, solvent-based and water-based technology.

While UV and UV LED both cure via a photochemical reaction—UV LED inks use longer wavelengths of light to cure (typically 385–405 nm), which requires a specific combination of photoinitiators and lamps.

What are the advantages of switching to UV LED curing technology?

Reduced Operating costs

Among the most attractive reasons to switch to UV LED-curing is the cost savings. Traditional UV mercury lamps require higher energy consumption, frequent lamp and bulb changes, and regular maintenance. On the other hand, UV LED lamps consume significantly less energy and require minimal bulb changes, leading to lower energy costs and CO2 emissions, as well as less downtime and maintenance. LED lamps also generate much less heat than traditional UV systems, making it easier and less expensive to maintain your temperature-controlled print environment.

The combined cost and energy savings of UV LED offset printing systems can add up to thousands of dollars per year, depending on your operations. Reach out to your lamp supplier to discuss your savings potential – contact a Zeller+Gmelin team member for a list of top suppliers.

On-press performance

Beyond cost savings, UV LED-curing systems can improve press performance and print quality. Key advantages include:

• “Instant On” Capability – Unlike mercury vapor lamps that require warm-up time, LED lamps and inks are ready to go immediately. This eliminates job delays and increases press efficiency.
• Minimal Heat Transfer to Substrates – Because LED systems generate less heat, the risk of damaging or distorting films, shrink sleeves and other heat-sensitive substrates is eliminated. This ensures precise registration in multi-color printing for high-quality, detailed applications.
• Faster Production Turnaround – With UV LED-curing, printed sheets are ready for the next processing steps immediately after printing. No need to wait for the sheets to dry before moving to finishing. This shortens internal processing time from point of order to point of delivery.

For printers handling sensitive materials or looking for ways to improve production efficiency, UV LED-curing can provide a competitive edge.

Sustainability benefits

On top of the cost savings and performance enhancements, UV LED offset printing systems offer environmental benefits. As previously mentioned, LED lamps require less energy to run and emit less heat. These systems also eliminate ozone emissions, helping printers reduce their carbon footprint. Plus, UV LED inks are formulated with 100% solids and reduced VOCs.

UV LED-curing provides notable sustainability advantages, making it worthwhile for printers seeking ways to be more environmentally friendly. Talk to your Zeller+Gmelin Product Manager to discuss our sustainable and globally compliant ink options.  

What should printers consider before making the switch to UV LED offset printing?

While UV LED curing poses several potential benefits, printers should consider a few important points before beginning the transition process.

The cost of transitioning equipment can be significant. We recommend discussing your initial investment and potential ROI with a lamp supplier to determine your budget and implementation schedule.  

Another option is hybrid curing—with both mercury vapor and LED lamps on the same press. While UV LED curing technology is continuously improving, mercury vapor lamps remain the best option for spot colors, coatings and low migration inks. Some printers choose to include a traditional UV lamp after the coating station. With this method, it’s important to confirm the inks used are appropriate for the curing method at each print station.

Dual-cure inks and coatings can help simplify your transition and reduce your raw material sku’s, making it easier on operators when selecting inks for each job. Zeller+Gmelin offers a wide variety of dual-cure UV LED inks for sheetfed offset and web offset applications, capable of curing under either system.

We also suggest asking some basic questions when considering making the switch:

• Are you looking for ways to be more sustainable?
• Can LED help you improve productivity and efficiency?
• Can your ink and coating supplier provide LED curable products that are comparable to what you currently run?

Zeller+Gmelin: Your Partner in UV LED Offset Printing

Zeller+Gmelin offers a variety of high-performance inks designed to meet the evolving needs of the UV LED offset printing industry. Our new 98 Series UV LED Film/Foil Process inks are specifically formulated for superior adhesion, color vibrancy, and durability across a wide range of litho applications.

Interested in learning more? Contact your local Zeller+Gmelin representative to discuss how UV LED inks and curing technology can transform your print operations.

The post Flipping the Switch: Advantages of UV LED Offset Printing first appeared on Zeller + Gmelin.

As experts in formulating compliant UV/LED inks, coatings and adhesives, we’ve put together this FAQ to break down the essentials of Prop 65—so you can focus on your business, not the fine print.

1. What Is Prop 65?

Proposition 65, formally known as the Safe Drinking Water and Toxic Enforcement Act of 1986, is a California law designed to safeguard residents from exposure to chemicals linked to cancer, birth defects, or reproductive harm. It mandates that businesses provide warnings if their products contain significant levels of these substances, such as lead, phthalates, or formaldehyde.

2. Who Must Comply with Prop 65?

Compliance is required for any business selling or distributing products in California, or manufacturing items that may reach California residents—including those based outside the state. This applies to business owners, printers, and compliance managers in the print and packaging sector. Exemptions exist for companies with fewer than 10 employees or products with chemical levels below designated “safe harbor” thresholds.

3. Which Chemicals Are Covered?

The Prop 65 list started with 30 chemicals in 1986 and now tops 1,000, all identified as potential carcinogens or reproductive toxins, with new chemicals added to the list every year. It includes substances that affect print and packaging manufacturers such as heavy metals, phthalates, bisphenol A (BPA), styrene, and certain solvents used in inks, coatings, and adhesives. View the full chemical list on the OEHHA website: https://oehha.ca.gov/proposition-65/proposition-65-list

4. When Is a Warning Required?

A warning is necessary when a product exposes users to a listed chemical above its “safe harbor” level. These thresholds—NSRL (No Significant Risk Level) for carcinogens and MADL (Maximum Allowable Dose Level) for reproductive toxins—determine compliance. If no safe harbor level exists for a chemical, businesses must evaluate exposure risks to decide if a warning is needed.

5. What Does a Prop 65 Warning Entail?

A Prop 65 warning must contain the word “WARNING” in bold and must be clear and reasonable, typically featuring language like:

WARNING: This product can expose you to [chemical name], which is known to the State of California to cause cancer and/or birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.

These notices may appear on product labels, websites, or in-store signage to inform consumers effectively.

6. How Can I Ensure My Products Meet Prop 65 Standards?

For printers, your choice of substrate, inks, coatings and adhesives will affect your Prop 65 compliance. Speak to your suppliers about testing inks, coatings, and packaging materials for Prop 65-listed chemicals. Compare results to safe harbor limits (where applicable) and maintain thorough documentation. Partnering with a forward-thinking ink supplier like Zeller+Gmelin, who prioritizes formulation compliance, can streamline this process.

7. What Are the Consequences of Non-Compliance?

Failing to comply can lead to steep penalties—up to $2,500 per day, per violation. Costs can escalate quickly with multiple products or prolonged exposure. Enforcement comes from the California Attorney General, district attorneys, or private citizens acting in the public interest, making adherence critical.

8. How Does Zeller+Gmelin Support Compliance?

We understand the complexities of Prop 65 packaging requirements. Zeller+Gmelin is dedicated to developing inks, adhesives and coatings that meet regulatory standards without compromising performance. Whether you’re producing labels or packaging, our expertise ensures your materials align with Prop 65 requirements for printers. Have questions or need tailored solutions? We’re here to assist.

Your Partner in Prop 65 Compliance

Mastering Prop 65—from its chemical list to its warning protocols—doesn’t have to be daunting. Zeller+Gmelin is your trusted partner in navigating these regulations with confidence. Contact us today to learn how our compliant inks and coatings can support your business.

The post Prop 65 Frequently Asked Questions: Essential Insights for Print and Packaging Professionals first appeared on Zeller + Gmelin.

At Zeller+Gmelin, we manufacture high quality dual-cure UV/LED inks that print on shrink seamlessly. In this blog, we’ll review some essential quality control properties and testing methods that can elevate your shrink sleeve printing game.

Quality Control Properties

Ensuring quality involves testing several critical properties:

• COF (Coefficient of Friction) – Kinetic and static
• Adhesion
• Shrinkability
• Blocking
• Flex

Each property contributes to the overall performance and durability of the shrink sleeve. Here’s how to test and manage them effectively.

Testing Procedures and Best Practices

1. COF (Kinetic and Static)

The coefficient of friction (COF) plays a crucial role in the application of shrink sleeves. Customers may require either slippery or controlled COF depending on their equipment.

Kinetic COF: This measures friction in motion, such as sleeves sliding over bottles. Too low, and the sleeves may bunch up; too high, and they may not slide properly. Typical ranges are 0.2–0.3.

Static COF: This measures the force needed to overcome static friction, crucial for preventing blocking when sleeves are stacked. Typical ranges are 0.2–0.6.

Testing Tip: Use a slip/peel tester under ASTM D-1894 standards for accurate COF measurements. Note that slide angle testers only measure static COF.

2. Adhesion

Adhesion ensures the ink bonds securely to the substrate. For UV shrink inks like NUVAFLEX which achieve shrink percentages similar to solvent gravure inks, adhesion testing goes beyond basic tape tests.

• Use crosshatch testing with standard 3M 600 or 810 tape.
• Activate adhesion with in-line corona treatment rather than focusing solely on dyne levels.

3. Shrinkability

Shrinkability is critical to ensure that the ink film adheres smoothly and resists defects like microcracks or flake-off.

Testing Methods:

• Boiling water soak (30 seconds): The most aggressive and revealing test.
• Industrial hot air dryer: A more practical, everyday option.
• Steam kettles or blowers: Also effective for shrink testing.

Check for smooth shrinking with no durability issues, opacity loss, or matting.

4. Blocking

Blocking can occur if sleeves cling or stick together, impacting application performance and final product quality.

• Simple Test: Fold a printed article ink-to-ink, press it with your thumb and forefinger, and check if the layers slide cleanly.
• Advanced Testing: Use slip/peel equipment for a more detailed analysis.

Proper curing tests confirm that the ink doesn’t stick to itself or the container in high-humidity environments.

5. Flex

Flex testing evaluates how well the printed ink withstands crumpling and twisting.

• Bicycle Crumple Test: Hold a sample in both hands, twist it in opposite directions, and inspect for flaking or cracking.

Flexibility testing ensures the ink can endure the rigors of shrink application and handling without compromising quality.

Final Thoughts

UV shrink sleeve printing is an art and science, and quality control is the glue that holds it all together. From COF to flex testing, each procedure offers insights that help you refine your process and deliver exceptional results to your clients.

By mastering these testing techniques, you can avoid costly reprints, reduce waste, and build trust in your printing expertise.

Need advice on inks or testing procedures? Contact the Ink Experts at Zeller+Gmelin—we’re here to help you achieve shrink sleeve perfection!

The post Key Testing Procedures for UV Shrink Sleeve Printing first appeared on Zeller + Gmelin.

As a leader in UV ink solutions, Zeller+Gmelin has provided this guide to help you avoid common mistakes and adopt best practices for managing your printing ink inventory.

The Importance of Ink Inventory Management

Raw material mismanagement causes a host of pain points for industrial printing operations. As one of the highest cost consumables and a driving factor for print quality, ink management is especially important to maintain profitability and customer satisfaction.

Effective inventory management ensures high quality inks are available when needed, helping you avoid downtime and expedited shipping costs and improve material utilization. Plus, a reliable ink supply supports on-time order delivery and consistent print quality.

Common Pitfalls in Ink Management

Knowing the risks of inventory mismanagement is the first step, avoiding these common mistakes is the next. Zeller+Gmelin is a leading provider of printing inks for flexo, offset and commercial applications. With over 150 years in the business, here’s some of the common inventory mishaps we’ve seen that affect printers’ bottom lines.

Overstocking or Understocking: Excess inventory ties up capital and risks obsolescence, especially with UV/LED inks which have a shorter shelf life than others. While understocking can lead to production delays and expedited shipping costs, reducing your profit margins and productivity.

Inadequate Rotation: Failure to rotate your inventory and follow the FIFO (First In, First Out) method is a leading cause of ink expiration. Using expired ink may result in improper curing or adhesion and color inconsistency.

Improper Labeling: Mislabeling or lack of tracking, leads to confusion about ink age, type, or intended use. Poor label practices could increase the likelihood of accidental use of expired or incorrect inks as well as cause delays in production to find the right inks or resolve labeling issues.

Lack of Usage Monitoring: Not keeping accurate usage data can result in inaccurate forecasting and missed opportunities to optimize ink ordering. Profit margins dip when expedited shipping is needed to produce an order on time.

Poor Container Sealing or Storage: Open or improperly sealed containers can lead to contamination, drying, or curing of inks. Be aware of incorrect temperature, humidity, or exposure to light. These factors can degrade the ink over time or cause premature curing resulting in more ink waste.

Without a proper ink management system in place, these inventory mistakes can negatively impact your daily operations  and may be the culprit of low profit margins affecting your bottom line.

Z+G Inventory Tips for Success

Avoiding common inventory issues doesn’t require complex methods, you can start with simple improvements that make a big impact. These tips from our team of experts are actionable steps that you can take in your ink room.

Use an Inventory Management System: Implement software to track ink inventory levels, expiration dates, and usage trends. This can be as easy as a spreadsheet or software on a dispenser. More advanced tracking software can integrate with your production schedule and equipment, such as automated dispensers with built-in tracking sensors for ink usage monitoring in real time.

Adopt FIFO Practices: Standardize your ink receiving process to always rotate the oldest inventory to the front and place newer products behind, following the FIFO method to reduce waste. Confirm expiration dates when rotating to ensure the inks expiring first are easily accessible.

Standardize and Label Clearly: Label all containers with batch numbers, production dates, and expiration dates. Use color-coded systems for quick identification between ink types or applications. Using QR codes, barcodes or RFID tagging can make stock tracking more efficient and reduce manual errors. Periodically, inspect labels to make sure important information is not worn or torn off – relabel as needed.

Set Minimum and Maximum Thresholds: To maintain balance, define reorder points and maximum stock levels for each ink type. Use consumption data from your tracking system, set up automated alerts in your software, and take note of supplier lead times to optimize this component of ink management.

Dispose of Expired Inks Safely: Create standard operating procedures related to the disposal of each ink type used in your pressroom, to ensure environmental and employee safety. Incorrect disposal of expired inks can harm the environment and increase disposal costs, not to mention that failure to correctly manage hazardous materials can result in fines or legal issues.

Conduct Regular Training: Train staff on proper handling, storage, and inventory practices for UV/LED inks to minimize human error. Establish clear protocols for leaks, contamination and light exposure to effectively address potential storage issues and/or safety concerns. Standardize these ink management processes in written format and incorporate them into your onboarding programs for all applicable employees.

The Importance of Regular Audits

Conducting ink inventory audits at regular intervals is another way to prevent issues like overstocking, misidentified, and expired inks. We recommend creating a schedule or checklist to standardize the process.

 For larger operations with significant ink usage (over 20,000lbs/month), monthly audits ensure that your inventory remains manageable and optimized. Smaller printers with stable usage patterns can typically operate on a quarterly audit schedule to maintain order.

Spot audits are good practice when discrepancies are expected or after significant events like an ink room move or a new press install. Operations of all sizes should consider annual comprehensive reviews to reconcile inventory data with physical stock and to review supplier performance.

Ink Storage Best Practices

Protect your ink quality with this checklist for storage best practices.

Control the Environment: Maintain appropriate temperature and humidity based on ink type. UV inks require cool, dark storage, ideally between 60°F–77°F (15°C–25°C) to prevent premature curing.  Whereas, water-based inks need protection from freezing, which can break down their formulation and render the ink unusable. Humidity can cause some inks to thicken or separate, as well as increase the risk of microbial contamination in water-based inks.

Maintain Proper Seals: Use airtight lids and reseal containers completely and immediately after use to prevent contamination or curing. Inspect seals for wear and tear during your audits and replace any damaged lids or gaskets promptly.

Store Away from Direct Light and Heat: UV-sensitive inks and coatings can cure or degrade with exposure. Make sure UV/LED inks are stored in opaque containers and stored away from direct sunlight or artificial light.

Check Condition Regularly: Inspect containers for leaks, rust, or swelling, and take immediate action if found. Swelling of containers can indicate contamination or chemical reactions within the ink and should be addressed immediately. Log your inspections and analyze the data for recurring issues or trends in deterioration.

Segregate Storage: Store inks by type (UV, solvent-based, water-based) and label the areas clearly to avoid cross-contamination. Store inks used for specific applications, such as specialty or food-safe inks separate from your general use inks. Also be sure to create a clearly marked “waste inks” area for any products that need to be disposed of according to regulatory guidelines.

Proactive ink management will lead to smoother operations and ultimate cost savings for you, and better quality for your customers. Get started today with Zeller+Gmelin to avoid production delays, improve production efficiency, and maintain regulatory compliance.

Ready to optimize your ink room setup? Our team can help with auditing your current inventory and providing recommendations for improvement. Contact the Zeller+Gmelin team for ink and coating solutions, expertly done.

The post Ink Management – Setting up Your Ink Room for Success first appeared on Zeller + Gmelin.

This year, it is pretty common knowledge that the printing industry is experiencing multiple delays and shortages in supply of critical components used in the printing process. Consumables such as inks, paper, films, containers and more are experiencing issues in their supply chain. Some of the hardest hit products in this sector are UV coating, varnish and overprint.

At Zeller+Gmelin, we still have many UV coatings, adhesives, varnishes and overprint products in stock and available. However, like everyone in the industry we are also experiencing the brunt of a restricted supply chain. In this blog, we offer tips and tricks for stretching your UV coating supply during this time of limited resources.

Tips from the UV Coating Experts at Z+G

Lower Anilox Volume. Using an anilox roll with lower cell volume will apply less coat weight on the substrate and help your coatings, varnishes, and overprints go further.

Patterned Plate. Try using a patterned plate to apply coating to your image instead of a flood coat to save product.

Film Overlaminate. Using an overlaminate film could provide the protection or special effect you are seeking without using your limited UV coatings supply.

Alternative Chemistry. Using an aqueous coating versus a UV coating could help save you from the need to use traditional coatings.

Oil Based Varnish. If you’re producing print using litho-web applications, you could switch from UV coating to an oil based varnish to achieve the same look and durability.

Talk to your Customer. If the relationship is good, talk to your customers and see which designs can be modified to forego UV coating for the short term or on specific jobs.

We’re In This Together

Though coatings are extremely important to many print applications, there are other ways to achieve the protection, security, special effects and functionality of coating products through this coating and varnish shortage.

Before the pandemic of 2020 and long after, we have always believed “we’re in this together.” Talk to your Zeller+Gmelin Ink Specialist today if you are experiencing trouble with UV coating shortages and we’ll work with you to get your operations back up and running, through thick or thin.

The post 6 Tips to Stretch Your UV Coating Supply during an Industry Shortage first appeared on Zeller + Gmelin.