Direct answer: Ink adhesion on a hard substrate depends on the exact material, coating, surface condition, compatible ink, preparation and curing process. Glass, metal and plastics vary widely; no single primer or cleaning method is guaranteed for every finish.
Engineering Principles and Components
| Topic | Function | Practical check |
|---|---|---|
| Surface and coating | The actual print surface may differ from the base material. | Identify coatings and supplier requirements. |
| Contamination | Dust, oil or residues may interfere with bonding. | Use only preparation methods approved for the surface. |
| Ink and cure | The ink and curing process must suit the system and application. | Check compatibility and use authorised test procedures. |
| End use | Handling, cleaning and environmental conditions affect performance. | Agree a relevant test and care instructions with the customer. |
Practical Shop Checklist
- Identify the substrate and coating rather than assuming all plastics or metals behave alike.
- Use supplier-approved preparation and observe solvent safety instructions.
- Apply a representative sample and test adhesion under agreed conditions.
- Do not claim dishwasher, outdoor or food-contact suitability without appropriate evidence.
Related Engineering Guides
Start with how a piezo printhead works and digital inkjet machine anatomy. For a machine-specific question, share your model on our contact page.
Frequently Asked Questions
Why is UV ink peeling off glass?
Possible causes include surface contamination, incompatible preparation, ink or curing. Diagnose and test the full process.
Does every plastic need the same primer?
No. Plastics and coatings vary; confirm the correct process for the actual item.
Is an alcohol wipe always safe?
No. Some finishes can be damaged. Follow the substrate supplier’s cleaning instructions and test first.
Does a cured surface guarantee adhesion?
No. Cure and substrate adhesion are separate considerations.
Are all UV prints food-safe?
No. Food-contact suitability must be supported by documentation for the complete application.
How should adhesion be tested?
Agree an appropriate test with the client and suppliers for the item’s intended handling and environment.
What should I record?
The substrate, ink, preparation, machine settings, sample result and customer approval.
