Metal packaging ink additives should be selected around the first failed interface: ink-to-metal wetting and adhesion, air control during manufacture and application, or the printed surface during stacking, coating, and converting. Before screening an additive, define the metal, pretreatment, primer or size coat, ink chemistry, cure schedule, and end-use exposure. Tinplate, tin-free steel, aluminum, and coated metal do not present the same surface.
This guide covers water-based, solvent-based, and UV-curable metal-decorating inks. It does not claim that an additive or raw material alone makes a finished package compliant for food contact, retort, sterilization, or any regulated end use.
Separate three common failure locations
| Failure location | Typical evidence | First Longchang route |
|---|---|---|
| Ink-to-metal or ink-to-primer interface | Retraction, pinholes, incomplete coverage, weak adhesion | Wetting: CHLUMIWE® 2100 |
| Mixing, grinding, pumping, or application | Persistent foam, entrained air, craters, density variation | Defoaming: CHLUMIAF® 3062 |
| Dried or cured print surface | Blocking, poor release, OPV or downstream handling conflict | Surface handling: CHLUMIAG® 3501 |
| After bake, retort, chemical exposure, or fabrication | Adhesion loss, discoloration, cracking, resistance failure | Reassess the full ink/coating construction and cure |
Quick comparison: 2100, 3501, or 3062?
Use the measured failure to choose between the CHLUMIWE® 2100 metal-ink wetting route, CHLUMIAF® 3062 foam-control route és CHLUMIAG® 3501 printed-surface route; do not combine them before single-variable screening.
| Termék | Primary screening purpose | Supplier use information | Essential validation |
|---|---|---|---|
| CHLUMIWE® 2100 | Spreading, wetting, and penetration on difficult or highly smooth substrates; acrylic coating surface control | 0.1–1%; water, solvent, and UV systems | Wetting, adhesion after full cure, foam, intercoat/OPV compatibility, and corrosion or resistance requirements |
| CHLUMIAG® 3501 | Anti-sticking, release, and overprint-varnish handling after the ink already wets the substrate | Listed for printing inks, OPVs, release coatings, and water/solvent/UV systems | Confirm current dosage; test blocking, intercoat adhesion, fabrication, tape, and package-specific resistance |
| CHLUMIAF® 3062 | Defoaming and foam suppression during ink manufacture or application | 0.1–0.5% for printing inks; 100% active; water, solvent, and UV systems | Validate any dilution; check craters, haze, adhesion, print density, and later coating |
These are supplier-published screening directions, not application approvals. Use the lowest effective addition and request the current technical, safety, and regulatory documentation before a production decision.
For waterborne metal packaging inks, control four extra variables
A waterborne route does not need a different additive-selection logic, but it does need tighter process records. Non-absorbent metal gives water nowhere to penetrate, while circulation and application can keep introducing air. Record these four variables beside every additive result:
- pH, when the binder or ink is pH-managed: state the measurement temperature and check the value again after aging or recirculation.
- Viscosity and temperature: compare samples at the same temperature and with the same measurement method; do not correct one sample with extra water during the trial.
- Foam through the real process: include mixing, pumping, return flow, and application rather than judging only a still laboratory cup.
- Drying and conditioning: keep air flow, metal temperature, film weight, bake or dry schedule, and the interval before adhesion or blocking tests constant.
Use the same three-way diagnosis: CHLUMIWE® 2100 for verified substrate-entry failure, CHLUMIAF® 3062 for persistent air that remains after mechanical causes are corrected, and CHLUMIAG® 3501 for dried-face handling after wetting and foam are already controlled. Waterborne chemistry alone is not a reason to add all three.
Use CHLUMIWE® 2100 for a verified wetting problem
Start with 2100 when a clean, correctly pretreated metal or primer still shows retraction, pinholes, incomplete coverage, or unstable laydown. First verify surface cleanliness, treatment, primer condition, ink viscosity, film weight, and cure. Oil, lubricant, oxidation, condensation, or inconsistent pretreatment cannot be solved reliably by adding more wetting agent.
Compare a blank with a compact dosage ladder. Evaluate the wet film, then test adhesion and resistance only after the specified bake, dry, or UV conversion. A visually uniform drawdown can still fail during forming, seaming, varnishing, retort, or chemical exposure.
Use CHLUMIAF® 3062 for a verified air problem
Move 3062 to the front when foam is generated during pigment dispersion, let-down, pumping, or application and remains long enough to affect coating weight, appearance, or process stability. Repair mechanical air entry and excessive agitation first. Then measure initial foam knockdown and long-term suppression; they are not the same performance.
Inspect the cured ink for craters, fisheyes, haze, color difference, and adhesion. If solvent dilution is used, the supplier specifically calls for stability and defoaming-performance testing before use.
Use CHLUMIAG® 3501 for printed-surface handling
Choose 3501 as the first surface comparison when wetting and foam are controlled but the cured print still blocks, releases poorly, or conflicts with an overprint varnish or later handling step. Include the actual stack pressure, bake history, OPV, fabrication, tape, and cleaning or product-resistance exposure in the evaluation.
Do not infer an optimum dosage from a different ink system. The public product page does not publish a dosage for 3501, so obtain the current technical sheet and test a supplier-agreed range.
A metal-packaging qualification matrix
| Stage | Keep constant | Measure |
|---|---|---|
| Drawdown | Metal lot, pretreatment, primer, film weight, viscosity | Coverage, craters, color, gloss, wetting |
| Cure | Bake time/temperature or UV dose, line speed, film temperature | Conversion, solvent/water release, appearance |
| Mechanical | Conditioning time and test method | Adhesion, rub, scratch, flexibility, fabrication |
| End use | Actual package construction and exposure | Blocking, OPV, chemical/product resistance, retort or sterilization where required |
| Compliance | Formula, layer position, use conditions, jurisdiction | Documentation, migration/set-off assessment, finished-article decision |
ASTM D3359 provides tape-test methods for rating adhesion of relatively ductile coatings on metallic substrates and explains important limits involving film thickness and operator technique. ISO 2836:2021 covers assessment of print resistance to liquid and solid agents, solvents, varnishes, and acids. Select the method that matches the customer’s construction and acceptance criteria.
Food-packaging compliance is a finished-article responsibility
For EU food-contact applications, Commission Regulation (EC) No 2023/2006 requires good manufacturing practice and specifically addresses transfer from printing inks on the non-food-contact side through the substrate or by set-off. The current EUR-Lex text should be read with the applicable framework, material-specific, and national rules.
A EuPIA food-contact principles and guidance emphasize formulation information, statements of composition, GMP, and migration risk assessment across the supply chain. A supplier dosage range or “packaging ink” application statement is not evidence that the finished package is compliant. Obtain current composition and regulatory information and validate the final printed article for its intended use.
Frequently asked questions
Which additive should I screen first for poor metal coverage?
After verifying cleaning, pretreatment, primer, viscosity, and cure, screen CHLUMIWE® 2100 as the wetting-first route. Do not add 3501 or 3062 unless the failure is respectively at the cured surface or in air control.
Can a defoamer improve pinholes?
Only when entrained air is the cause. Retraction from contamination or inadequate wetting requires a different correction. Inspect the defect under magnification and compare a controlled blank.
What must be tested after adding a surface additive?
At minimum: adhesion after full cure, intercoat or OPV adhesion, blocking, rub/scratch, fabrication, and the chemical, thermal, retort, or sterilization exposure required by the package.
Do these recommendations certify food-contact use?
No. Regulatory suitability must be established from current product documentation and the migration/set-off assessment of the complete finished package.
Request a metal-packaging ink comparison
Send the metal and pretreatment, primer, ink chemistry, cure schedule, film weight, defect location, end-use exposure, current additive package, and acceptance method. Ask Longchang Chemical for a metal-packaging ink sample shortlist.