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Oct 12,2026
Plate edge lift is one of the most common—and most frustrating—problems in flexographic printing. When a plate edge lifts from the mounting tape, ink transfers to areas that should be unprinted, causing print defects, registration problems, and press downtime. The benchmark for most flexo printers is zero edge lifting during a production run. Achieving that requires a systematic approach: understanding the root causes, applying correct mounting procedures, and maintaining proper plate storage conditions. This article explains why plate edge lift happens and provides a practical framework for preventing it.
To explore the available options, review the flexible printing plate configurations designed for different mounting systems and applications.
Plate edge lift causes more than just a visual defect. When an edge lifts, the plate no longer transfers ink uniformly to the substrate. The lifted area may print heavy, print light, or not print at all—depending on how the plate separates from the tape. In multi-color jobs, edge lift can cause registration errors that are difficult to diagnose because the problem appears and disappears as the plate flexes during the run.
The real cost, however, is press downtime. When edge lift is detected mid-run, the press must stop, the plate must be remounted, and production resumes. Each stop consumes time, material, and operator attention.
What happens: The back of the plate is contaminated with soap, oil, grease, or photopolymer residue from the plate-making process. These contaminants reduce the adhesion between the plate and the mounting tape, allowing the edges to lift.
Why it happens: New plates often carry residue from solvent processing. Reused plates may pick up ink or cleaning solution on the back during handling. Even a small amount of oil from a fingerprint can compromise adhesion.
How to prevent it: Clean the back of the plate with isopropyl alcohol (IPA) before mounting. IPA is the most effective solvent for removing processing residue and ink contamination from the plate back. For reusable plates, clean the back after every run before storing. Never handle plate backs with bare hands—use nitrile gloves to avoid transferring oils.
What happens: The plate is not pressed firmly enough against the mounting tape, or the pressure is not applied evenly across the full width of the plate. Air pockets become trapped under the plate, creating areas where the plate does not adhere properly.
Why it happens: Applying insufficient pressure to the plates, or failing to apply equal pressure across the whole width of the sleeve, leads to edge lifting and air bubbles. If a build-up of contaminants on the rear of the plate impairs adhesion, the problem worsens.
How to prevent it: Use a rubber roller or lay-on roller to apply even pressure across the entire plate during mounting. Work systematically from the center outward, removing all air pockets as you go. Consider applying a plate edge primer or sealer to improve edge adhesion, especially where the full-height plate is visible at the join.
What happens: Plates stored improperly curl toward the image side. When a curled plate is mounted, the edges do not lie flat against the tape. Even if the plate adheres initially, the stored curl creates tension that causes edges to lift during the run.
Why it happens: Unexposed plates stored in conditions that expose them to heat, humidity, or UV light may deform. Plates stored on end rather than flat may develop a permanent curl. Older or deformed plates are more prone to edge lift.
How to prevent it: Always store plates facing down and flat when possible. Interleave the white foam from your plate boxes between clean, dry plates to protect print surfaces. Keep plates in a cool, dry storage area with good air circulation. For unexposed plates, the recommended storage temperature range is 0°–40°C (32°–104°F), with relative humidity between 40% and 60%.
What happens: The mounting tape does not provide adequate adhesion for the plate type, substrate, or press speed. Tape that is too soft may allow the plate to flex and lift. Tape that is too hard may not conform to the plate back, leaving gaps at the edges.
Why it happens: With the introduction of Fixed Color Palettes (FCP) and Extended Color Gamut (ECG) printing, there is a greater need for accurate plate alignment and press consistency. Using the incorrect tape for the process, or tapes that vary in thickness, leads to misregistration and poor print quality. Using the wrong tape can also make demounting difficult, causing plate damage and slower changeovers.
How to prevent it: Select mounting tape based on the plate type, substrate, press speed, and job requirements. Verify tape thickness consistency across the roll. For high-speed printing or long runs, use tapes with higher adhesion and consistent foam hardness. Store plates and tapes at the same temperature to prevent condensation on components.
What happens: The plate is not completely dry when mounted. Trapped solvent or water inside the photopolymer causes the plate to swell or change thickness during the run. As the plate dimensions change, the edges may lift.
Why it happens: Drying time is often reduced to speed up plate production. But incomplete drying leaves solvent trapped in the polymer. Plates that are not fully dried also have inconsistent thickness, which affects mounting and registration.
How to prevent it: Verify plate thickness with a micrometer after drying. A properly dried plate returns to its original thickness. If the thickness is greater than specification, drying is incomplete. Plates should be dried completely before post-exposure and mounting.
| Step | Action | Why |
|---|---|---|
| 1. Clean plate back | Wipe with IPA before mounting | Removes processing residue and oils that reduce adhesion |
| 2. Clean cylinder/sleeve | Ensure cylinder is clean and dry before mounting | Extends plate life and reduces plate damage |
| 3. Apply tape correctly | Follow manufacturer guidelines for tape application | Ensures consistent adhesion across the plate |
| 4. Mount with even pressure | Use a rubber roller; work from center outward | Removes air pockets and ensures uniform contact |
| 5. Seal plate edges | Apply plate edge primer/sealer if needed | Improves edge adhesion and prevents lift |
| 6. Store plates properly | Store flat, facing down, with interleaving foam | Prevents curling and surface damage |
| 7. Control storage conditions | Temperature 0°–40°C, humidity 40%–60% | Maintains plate dimensional stability |
For detailed guidance on plate handling and mounting for your specific equipment, discuss your material and production requirements with the technical team.
Not all edge lift is caused by mounting or storage. Sometimes the plate itself has characteristics that make it more prone to edge lift. Plates with inconsistent thickness or poor dimensional stability may not lie flat even with perfect mounting technique.
STRONG's flexible printing plate range includes models designed for consistent thickness and dimensional stability. The SF-DGS Digital Versatile Flexo Plate is a softer, less rigid photopolymer designed for corrugated board surfaces, offering superior printing quality with sharper images, more open intermediate depths, finer highlight dots and less dot gain. For applications requiring higher hardness, the SF-GT Analog Photopolymer Sheet Plate uses a high-hardness resin system with Shore A hardness reaching 70 to 80.
For plate storage and handling recommendations specific to your plate type, explore the service and support resources available.
Plate edge lift is caused by one or more of the following: contaminated plate back, insufficient or uneven mounting pressure, plate curling from improper storage, wrong mounting tape selection, or incomplete drying after plate-making. Addressing all five factors is necessary for reliable edge adhesion.
Clean the back of the plate with isopropyl alcohol (IPA). IPA is the most effective solvent for removing processing residue, ink, and oils from the plate back. Wipe thoroughly and allow to dry before mounting.
Store plates flat, facing down, in a cool, dry area. The recommended temperature range is 0°–40°C (32°–104°F), with relative humidity between 40% and 60%. Interleave foam from the plate boxes between plates to protect surfaces.
Select tape based on plate type, substrate, press speed, and job requirements. Verify tape thickness consistency across the roll. For high-speed printing or long runs, use tapes with higher adhesion and consistent foam hardness. Consult your tape supplier for specific recommendations.
If edge lift is detected mid-run, the press must be stopped and the plate remounted. Attempting to continue the run with a lifted plate will produce defective prints and may cause plate damage. Prevent edge lift by following proper mounting and storage procedures before the job starts.
Plate hardness can influence edge lift. Softer plates are more flexible and may conform better to the mounting tape, but they can also deform more under press pressure. Harder plates may not conform as easily to tape surfaces. Matching plate hardness to the substrate and selecting the correct mounting tape for that hardness is essential.
Flexo plate edge lift is preventable. The root causes—contaminated plate backs, uneven mounting pressure, plate curling from poor storage, wrong tape selection, and incomplete drying—can all be controlled with proper procedures. Cleaning the plate back with IPA before mounting, applying even pressure with a rubber roller, storing plates flat in controlled conditions, and selecting the right mounting tape for the job are the key steps.
When edge lift does occur, it costs more than the plate itself: press downtime, material waste, and delayed deliveries. Investing time in prevention is always cheaper than correcting mid-run failures.
If you are experiencing recurring edge lift problems or evaluating plate options for demanding applications, review the available flexible printing plate configurations and discuss your specific mounting and storage requirements with the supplier.
Disclaimer: The information in this article is provided for general guidance only. Plate mounting, storage, and handling procedures vary by plate type, equipment, and production environment. Actual results should be verified through testing on your production equipment. Buyers should confirm specifications with their supplier before placing an order.
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