Choose a flexographic ink additive only after locating the defect in the print process. Poor coverage on film is primarily a wetting problem; persistent air in a recirculating ink is a foam-control problem; and scuffing, blocking, or release after printing is a cured-print surface problem. Treating all three with one “surface additive” usually makes the press trial harder to interpret.
This system-neutral guide covers water-based, solvent-based, and UV flexographic inks. It compares three Longchang starting routes and shows how to run a controlled press-side screen without confusing additive effects with anilox, plate, viscosity, drying, or substrate-treatment variation.
Stabilize the flexo process before changing the additive
Record ink chemistry, viscosity and measurement temperature, pH where relevant, anilox volume and line count, plate and tape, press speed, drying or UV dose, substrate and surface treatment, and the age of the ink. A change in any of these can move density, trapping, dot gain, laydown, or cure independently of the additive.
ISO 12647-6:2020 defines process-control aims and tolerances for four-colour flexographic printing. The Flexographic Technical Association’s FIRST 7.0 framework likewise emphasizes optimization, fingerprinting, measurement, and repeatable process control. Use the additive trial inside a controlled print condition rather than as a substitute for one.
| Where the defect appears | Evidence to collect | First additive route |
|---|---|---|
| At initial contact with film or foil | Surface treatment, drawdown coverage, pinholes, adhesion | Wetting: CHLUMIWE® 2100 |
| In the pan, pump, chamber, or return line | Foam height, air entrainment, density/viscosity drift | Defoaming: CHLUMIAF® 3062 |
| After drying, curing, rewinding, or finishing | Rub, blocking, release, overprint/lamination result | Surface handling: CHLUMIAG® 3501 |
| Across the whole press result | Anilox, plate, ink condition, drying, substrate treatment | Correct process variation before additive screening |
Quick comparison of three Longchang routes
| Product | Primary screening job | Supplier use information | Trial watchpoint |
|---|---|---|---|
| CHLUMIWE® 2100 | Spreading and wetting on difficult or highly smooth substrates, including PE, PP, polyester, and packaging materials | 0.1–1% on total formulation; water, solvent, and UV systems | Do not use extra wetting to mask inadequate film treatment; check adhesion, foam, and intercoat compatibility |
| CHLUMIAG® 3501 | Printed-face anti-sticking, release, and overprint-varnish compatibility after wetting is acceptable | Listed for printing inks, overprint varnishes, release coatings, and water/solvent/UV systems | Confirm dosage with the current technical sheet; test blocking, rub, overprint, lamination, and sealing |
| CHLUMIAF® 3062 | Defoaming and foam suppression where entrained air disrupts ink preparation or circulation | 0.1–0.5% for printing inks; 100% active; water, solvent, and UV systems | If pre-diluted, validate stability and defoaming; check craters, haze, density, and later coating/lamination |
When CHLUMIWE® 2100 is the logical first screen
Choose the wetting route when a controlled drawdown or press sample retracts, leaves pinholes, produces incomplete coverage, or shows weak initial adhesion on a low-surface-energy film. Confirm the substrate treatment at the time of printing; treatment can decay during storage, and contaminated film can produce the same symptom.
Run a blank and a low-to-high dosage ladder. Measure coverage, color strength or density, dot or fine-line reproduction, foam, and adhesion after full dry or cure. Stop increasing dosage when coverage is stable: further surface-tension reduction may create foam, intercoat issues, or excessive penetration without improving print quality.
When CHLUMIAF® 3062 should move ahead
Select the defoamer route when foam persists in the ink preparation, chamber, pump, or return line and creates density variation, pinholes, overflow, or unstable transfer. First repair mechanical air leaks, return-line drop, pump cavitation, and excessive agitation. Then compare 3062 at the lowest effective level.
Measure knockdown speed and long-term foam suppression separately. Also inspect the dry print for craters, fisheyes, haze, color shift, and adhesion. A fast foam collapse is not a pass if the printed surface becomes defective.
When CHLUMIAG® 3501 is the better comparison
Move to a printed-face surface route when substrate wetting and foam are already controlled but the dried or cured print still has anti-sticking, release, rewinding, or overprint-varnish problems. Because later lamination, coating, sealing, and tape operations depend on surface condition, include those steps in the trial rather than testing slip or release alone.
A press-relevant trial sequence
- Qualify with drawdowns. Reject combinations that show craters, haze, poor wetting, color change, or loss of adhesion before using press time.
- Run one additive variable at a time. Keep viscosity, pH, temperature, anilox, plate, speed, dryer or UV dose, and substrate lot constant.
- Sample at defined intervals. Collect startup, steady-state, and aged-ink samples to catch recirculation and foam-stability effects.
- Condition before final testing. Many water-based inks need time after printing for final adhesion and resistance development; use the customer’s real converting interval.
- Test downstream operations. Rewind, block, rub, overprint, laminate, seal, or tape the sample as required by the package construction.
For laboratory comparison of abrasion on printed materials, ASTM D5264 describes the Sutherland rub tester and highlights the effects of shipment, storage, and handling. For resistance to liquids, solvents, varnishes, and other agents, ISO 2836:2021 provides applicable methods for flexo and other print processes. Neither reference establishes food-contact compliance.
What to report after the trial
- ink chemistry, batch age, viscosity, temperature, and pH where relevant;
- substrate, treatment level and measurement time;
- anilox, plate/tape, speed, drying or UV conditions, and film weight;
- additive dosage, dilution, addition stage, and mixing method;
- density or color, coverage, dot/fine-line result, foam, and press stability;
- adhesion, rub, blocking, coefficient of friction, lamination or overprint, and seal performance after the agreed conditioning period.
Frequently asked questions
Which additive should I test first in a flexographic ink?
Use 2100 for a verified wetting failure, 3062 for a verified foam-control failure, and 3501 for dried-print anti-sticking or release handling. If the press condition is unstable, control it before comparing additives.
Can a wetting additive fix poor film treatment?
It may improve coverage, but it does not restore a contaminated or under-treated substrate. Confirm treatment and adhesion first so the additive is not masking an unstable interface.
Should the lowest-foam drawdown automatically win?
No. The selected formulation must maintain transfer, color, coverage, adhesion, rub resistance, and downstream compatibility through the full recirculation interval.
Are these products automatically suitable for food packaging?
No. Suitability depends on current product documentation, the complete ink and package construction, migration and set-off risk, use conditions, and target regulations. The converter and responsible compliance specialist must validate the finished package.
Request a flexographic ink additive shortlist
Send the ink chemistry, substrate and treatment, press speed, anilox, viscosity/pH window, defect location, current additive package, cure conditions, and downstream tests. Ask Longchang Chemical for a flexo-focused sample recommendation.