Printing on BOPP Film: How to Achieve Bright Colors, Readable Text, and Stable Results Throughout the Print Run
Why printing on BOPP sometimes “fails” (and how it shows up)
If you have ever run branded film in production, you probably know the symptoms: dull colors, small text that blurs, dirty contours, and instability across the roll. This is exactly what people mean when they say “the print does not hold” or “it was fine yesterday, but not today.”
In most cases, the root of the problem is the film surface: the ink does not wet it properly, adhesion is weak, and then a whole chain starts — smudging → dusting/fading → instability. That is why the first building block of any stable print process is corona treatment + dyne control.
BOPP for printing: which film to choose for the task
BOPP is a rigid, “crisp” material with high transparency and gloss, good tear strength, and solid barrier properties. It is used in flexographic printing, lamination, and flexible packaging production, and the typical thickness range for BOPP is 15–40 microns.
To make the right choice, ask yourself 3 simple questions:
1) Do you need sealed seams?
Then you need BOPP with a heat-sealable copolymer layer. This heat-seal layer ensures stable seam sealing during the packaging process (it can be applied to one or both sides).
2) Do you need the print to “hold”?
Then you need BOPP with an activation layer (corona treatment) — this is what increases surface energy and gives the ink proper adhesion.
3) Do you need a cone or sheet without sealing?
Then BOPP without a heat-seal layer is often used — it is typically chosen for cone-shaped flower bags and sheets.
Bonus: in terms of design, BOPP can be transparent / white / pearlized / metallized / matte — and this often creates a more “premium” look without making printing more complicated.
Corona treatment and dyne control: the foundation for bright colors and durable printing
A simple explanation: corona treatment changes the top layer of the film so the ink wets the surface instead of “beading up” into droplets. If wetting is poor, adhesion is weak — and that leads to dusting, rubbing off, and dull, grayish color.
A practical rule from technical sources: the surface energy of the film should be 7–10 dynes/cm higher than the surface tension of the liquid (ink/solvent). In the Enercon example, if the ink surface tension is about 30 dynes/cm, the material should be at least 37–40 dynes/cm, otherwise wetting and adhesion will be insufficient.
How this is checked in production: a dyne test using dyne pens. Avery Dennison describes a simple approach in its technical bulletin: you draw a line with a dyne pen and see whether it stays continuous — this is a quick way to check the surface energy level.
An important warning: the effect of corona treatment can decrease over time, so the discipline of “test → print/laminate” is not bureaucracy — it is what keeps the print run stable.
Surface print or reverse print on BOPP: what to choose and when
The logic is simple:
- Surface printing — on the outside surface (fast, simple, but abrasion resistance must be tested).
- Reverse printing — on the inner side, often under lamination, so the ink is “locked in” and becomes more resistant to rubbing and scratches.
If your packaging experiences a lot of friction in logistics (boxes, conveyors, warehouse handling), reverse printing + lamination often provides a much more stable premium effect with fewer complaints about abrasion.
How to get “bright colors” in flexographic printing: a practical block
Here is a short algorithm that really works:
- Surface treatment (corona) is a must. Without it, you will try to “squeeze out” color through machine settings and still end up with instability.
- Anilox + ink transfer. The anilox roller and its condition are among the key factors for even ink laydown and solid density.
- Ink viscosity / feed. If the ink is too “wet,” small text will spread; if it is too “dry,” you will get streaks and dusting.
- Substrate / visual effects. If you want a more premium look, metallized BOPP or lamination can enhance the visual result — but only after the base process is stabilized.
How to make small text readable (without ruining the print run)
Small text is the first thing to suffer — because of dot gain, excessive pressure, and incorrect ink rheology. So the rule is: first process discipline, then design heroics.
What should be agreed with the technologist before launch:
- minimum font size and line thickness (depends on the print configuration, so do not guess);
- rules for reverse-out text (white text on a colored background is a risk zone);
- no “hairline” strokes or tiny QR codes without a test print.
Stability throughout the print run: what to control at start-up and during production
The most convenient way is in the format: goal → what affects it → how we control it.
| Goal | What affects it | How we control it |
|---|---|---|
| Brightness / density | corona (dyne), anilox, viscosity, drying | dyne test before printing; viscosity control; solid coverage check |
| Readable text | pressure / impression, overly “wet” ink, dot gain | test prints, approval of minimum font size / line thickness |
| Stability across the roll | dyne level, anilox cleanliness, color registration | QC checklist at start-up and during the run, registration control |
Typical flexographic printing defects on film — and how to avoid them
Poor adhesion / dusting → cause: low dyne level / no corona → solution: corona treatment + dyne control.
Smudging, dirty contour → cause: too much ink / too much pressure → solution: adjust transfer (anilox), viscosity, and impression.
Streaks / mottle → cause: unstable feed / anilox / drying → solution: clean anilox + correct drying mode.
Color variation across the roll → cause: drift in ink parameters + unstable surface → solution: control dyne level and viscosity at start-up and during the run.
Artha-S capabilities for printing on BOPP
Artha-S performs roll-to-roll flexographic printing and works with different types of BOPP (with heat-seal layer / without heat-seal layer / with activation layer).
Printing equipment: Flexotechnika Tachys, ФДР 850/6, FPHS-6HS.
Technical printing parameters: up to 8 colors, material width 300–1200 mm.
Technical requirements for the artwork
To avoid surprises during the print run, prepare:
- files: AI or PDF (PDF/X-1a or another agreed format);
- colors: CMYK / Pantone (to be agreed);
- clearly mark transparent areas, solid fills, gradients;
- “risk zones”: small white text on color, thin lines, large solid fills — all of this is best approved through a test print;
- important: exact minimum font sizes and line thicknesses depend on the print configuration and are approved before production starts.
Checklist 1: what to check before launching the print run
- dyne level / presence of corona treatment (quick dyne test)
- anilox condition (cleanliness / transfer)
- ink viscosity and feed stability
- impression / pressure and test for small text
- abrasion test (especially for surface printing)
Checklist 2: what to prepare for a quotation
- product and packaging format (roll / bag, surface or reverse printing)
- BOPP: whether a heat-seal layer is needed; whether corona treatment is needed
- film thickness (within 15–40 microns for BOPP)
- roll width (within 300–1200 mm)
- number of colors (up to 8) + artwork / design idea
- print run volume (minimum order quantity for printed film — from 300 kg)
FAQ
1) Why might ink adhere poorly to BOPP?
Most often because there is no corona treatment or its effect has faded: the surface energy is too low and wetting is weak. A common guideline is that the surface energy should be 7–10 dynes/cm higher than the liquid tension; people often refer to ~37–40 dynes/cm as the minimum for proper ink wetting.
2) Surface print or reverse print — which is better?
Surface print is simpler, but abrasion resistance must be tested. Reverse print under lamination gives better ink protection and more color depth.
3) How do you make small text readable?
Do not “force” the process: control impression pressure, viscosity, and anilox settings, and agree the minimum font sizes with the technologist before launch.
4) Why does color vary during the print run?
Usually because of drift in dyne level, viscosity, anilox transfer, and registration. The solution is disciplined parameter control.
5) What is the minimum order quantity for printed film?
According to the commercial policy — from 300 kg.
Artha-S performs flexographic printing of up to 8 colors on BOPP (with selection of heat-seal layer / no heat-seal layer and corona treatment depending on the task) and works in a roll-to-roll format.
