Frequently Asked Questions

Problems with adhesion of UV coating are primarily caused by one or a combination of the following factors. One is the use of inks that are not free of waxes or Teflon. Inks have waxes or Teflon in them to give them a greater rub resistance. The wax or Teflon acts much like wax on a car, causing the coating to bead up and not stick to the ink. Be sure to use inks without wax or Teflon to eliminate problems.

Another factor is slow drying of ink. The slow drying inks are usually not completely dry before they are coated. This is particularly true with multiple overprints and areas of heavy ink coverage. The slow drying inks release vapors as they dry. This interferes with the bonding of the water base and UV coating and can be aggravated by the heat of the curing unit. Eliminate the use of slow drying inks when coating to avoid potential problems.

The third factor is the VOC (Volatile Organic Content) of the inks. Inks that are to be coated, either with aqueous or UV, need to have a low VOC formulation. Low VOC inks (also called High Solid inks) have VOCs below 10%.

The fourth factor is the use of alcohol substitutes in fountain solutions. Many alcohol substitutes contain glycol that interferes with bonding of the UV coating to the substrate. You’ll need to use an alcohol substitute that does not contain glycol or replace the alcohol substitute with alcohol.

Metallic inks are normally manufactured from raw metal that has been milled into flat platelet type particles. To ensure an acceptable degree of luster the layers of metal particles must remain separate after the ink is laid down. This is achieved by adding a stearate type lubricant to the metal particles during the milling process.

Two primary factors influence the manner in which a metallic ink accepts a laminate or coating:

1. The lubricant added in the manufacturing process of the inks can migrate to the surface as the ink dries. This layer of lubricant causes reticulation when the ink is UV coated since it will not allow the coating to wet out over the substrate. During the lamination process the adhesive is unable to bond to the lubricant on the surface and this results in poor adhesion.
2. More prevalent is the poor cohesive binding of the metal particles in the ink. Consequently, when the ink is UV coated or laminated, adhesion only occurs on the surface or top layer of the metal particles in the ink.

Since the layers of metal are not bound tightly together, UV coating will “flake off” along with the top layers of ink. Laminated inks, especially where the metallic ink bleeds over the trim, will delaminate when subjected to stress. There are metallic inks that can be coated or laminated. Unfortunately, due to compromises in the manufacturing process they do not have the same degree of luster and are sometimes referred to as “simulated” metallics.

Yes, some PMS colors react to the chemistry used in the UV coating process. Reflex blue, Rhodamine red and some purples have a tendency for fading after UV coating, so special care should be taken when preparing the project for post press UV coating. Also, please note that many PMS colors contain Reflex blue – your ink supplier may be able to offer an alternative mixing ink for this application. The film lamination process is not normally effected by these colors.

An area around the perimeter of the sheet is needed to apply the film so that the laminate does not encroach on the printed copy, and, at no time does the film hang off the edges of the sheet. It is also necessary to maintain a clean Gripper and Side Guide so that subsequent processes have undisturbed registration points to work from.

An in-line aqueous “primer” has been proven to work successfully in most applications, it is always recommended that testing be done to determine the compatibility between UV coating and press applied coating prior to running.

UV coating typically requires a smooth and consistent surface for proper adhesion and curing. Applying UV coating directly onto uncoated stock can present several challenges and may not yield satisfactory results. Here are a few reasons why UV coating is not typically applied over uncoated stock:

1. Absorption and uneven coating: Uncoated stock, such as plain paper, is porous and tends to absorb liquids, including UV coating. When UV coating is applied to an uncoated surface, the coating may penetrate the paper fibers unevenly, resulting in a blotchy or inconsistent appearance. The coating may not adhere properly, leading to poor coverage and adhesion issues.
2. Poor drying and curing: UV coating relies on ultraviolet light to cure and harden the coating. However, uncoated stock does not reflect UV light efficiently, making the curing process challenging. As a result, the coating may not dry or cure adequately, leading to tackiness, smudging, or poor durability.
3. Compatibility and adhesion issues: UV coatings are designed to bond with coated or non-porous surfaces. Uncoated stock lacks the smoothness and non-porous nature required for proper adhesion. The coating may not adhere well to the uncoated surface, causing it to peel, crack, or flake off over time.
4. Color and texture alteration: Applying UV coating over uncoated stock can alter the appearance of the underlying print. The coating may change the texture, absorbency, and color of the uncoated surface, potentially resulting in undesirable visual effects or color shifts.

To achieve satisfactory results, it is recommended to apply a primer or coating specifically designed for uncoated stock before applying UV coating. The primer should create a smooth and non-absorbent surface that facilitates proper adhesion and curing of the UV coating.

When it comes to laminating digitally printed press sheets, there are a couple of reasons why you might need a different film laminate type compared to traditional offset printing. Here are some key considerations:

1. Toner adhesion: Digital printing utilizes toner-based technology, which can have different adhesion properties compared to ink used in offset printing. Some standard laminates may not adhere well to toner, leading to issues such as delamination or peeling. Therefore, digitally printed sheets require a laminate specifically designed for digital printing that offers superior toner adhesion.
2. Enhanced print protection: Digital prints can be more susceptible to damage from moisture, UV exposure, and abrasion compared to offset prints. Therefore, using a laminate that offers superior protection against these factors, such as UV-resistant or scratch-resistant laminates, can help prolong the life and quality of your digitally printed materials.

By using a film laminate specifically tailored for digital printing, you can ensure optimal adhesion, protection, and desired finishing effects for your digitally printed press sheets.

Yes, there are laminating films available that are food safe, and FDA approved. These materials are designed specifically for applications where direct or indirect contact with food is involved, ensuring that they meet the necessary regulatory requirements for food safety.

When selecting laminating films for food-related applications, look for products that explicitly state their compliance with FDA regulations. These materials are typically manufactured using food-grade materials that are safe for use with food products.

You can find FDA-approved options made from materials like polyester (PET) that are suitable for food packaging, labels, and other applications requiring direct food contact. These films should be free from harmful substances and contaminants that could migrate into the food.

Yes, it is possible to film laminate over corrugated materials. Film laminating can provide added protection, durability, and visual enhancement to corrugated substrates. Here are a few considerations when laminating over corrugate:

1. Suitable laminating films: Choose laminating films that are specifically designed for bonding to corrugated materials. These films should have good adhesion properties to ensure a strong bond with the corrugated surface.
2. Corrugated surface preparation: Before laminating, ensure that the corrugated surface is clean and free from dust, dirt, or any other contaminants. This helps to promote better adhesion between the laminating film and the corrugate.
3. Laminating process: The laminating process for corrugated materials may require adjustments compared to laminating on flat surfaces. The nature of corrugated materials can affect the feeding, alignment, and pressure settings during the laminating process. It’s important to follow the manufacturer’s instructions and perform test runs to optimize the lamination process for corrugated substrates.
4. Considerations for box folding: If the laminated corrugated material will be used for folding into boxes or structural elements, ensure that the laminate film is flexible enough to allow for proper folding without cracking or delamination. Choose films with appropriate flexibility to accommodate the folding process.

Film laminating over corrugate can provide benefits such as moisture resistance, improved print quality, increased durability, and protection against scuffs or scratches. It can also enhance the visual appearance of the corrugated material by adding gloss or matte finishes.

Consulting with a professional laminating supplier or service provider can help you select the appropriate laminating films and provide guidance on the specific considerations and techniques for laminating over corrugated substrates.

UV-cured offset ink is a type of ink that is hardened and dried through a photochemical process using ultraviolet (UV) light. It creates a durable and fast-drying ink film on the surface of the substrate. Thermal lamination, on the other hand, involves using heat and pressure to bond a thin plastic film onto a printed surface, providing protection and enhancement.

The issue you described, where layers of ink are sometimes removed when thermal laminate is applied and then removed, could be attributed to a few factors:

1. Ink Adhesion: UV-cured inks generally have excellent adhesion properties. However, if the ink is not properly cured or if the substrate surface is not suitable for good ink adhesion, it may not adhere well to the substrate. In such cases, the bond between the ink layer and the substrate may be weak, leading to the ink being partially or fully removed when the laminate film is applied and peeled off.
2. Laminate Bonding Strength: The thermal laminate film is designed to adhere firmly to the substrate surface. When the laminate is applied and heated, it creates a strong bond with the surface. If the bond between the UV-cured ink and the substrate is weaker than the bond between the laminate film and the ink, the ink may be pulled off when the laminate is removed.
3. Ink Film Thickness: The thickness of the ink film can also play a role. If the ink layer is too thick, it may not fully cure during the UV curing process, resulting in a soft or tacky surface. When the laminate is applied and removed, it can lift off the partially cured ink layer.

To prevent or minimize this issue, several steps can be taken:

1. Ensure Proper Ink Curing: Proper curing of UV-cured ink is crucial. Make sure the ink is exposed to sufficient UV light to fully cure and harden. Inadequate curing can lead to weak adhesion and subsequent ink removal.
2. Substrate Preparation: Ensure that the substrate is clean, dry, and properly prepared for printing. Surface contaminants, moisture, or incompatible coatings on the substrate can affect ink adhesion and cause delamination issues.
3. Optimal Ink Thickness: Control the ink film thickness within the recommended range. Excessive ink thickness can hinder proper curing and lead to poor adhesion.

By addressing these factors, you can improve the adhesion between the UV-cured offset ink and the substrate, minimizing the risk of ink removal when thermal laminate is applied and removed.