Overview
ISO/TR 12705:2011 defines a laboratory method to evaluate the tendency of an ink, substrate and printing procedure to produce chemical ghosting in sheet‑fed offset lithography on coated papers or foils. The method uses a printability tester (per ISO 2834‑1) to prepare paired test specimens and a test procedure to induce ghosting under simulated output‑stack conditions. The presence and severity of chemical ghosting are determined by visual evaluation of test images.
Key Topics
- Scope: Applies only to oxidative‑drying inks on coated papers or foils and evaluates specific ink–substrate combinations.
- Test principle: Two test prints are prepared-one with a large uniform ink area and one with a smaller area that will face the larger area when stacked. Sheets are stored facing each other under simulated press output‑stack conditions to induce ghosting.
- Apparatus & settings:
- Use a printability tester meeting ISO 2834‑1; record all settings.
- Suggested printing pressure and speed: 200 N/cm and 1 m/s (as stated in the Technical Report).
- Condition samples and perform tests under ISO 187 standard atmosphere.
- Materials:
- Oxidative‑drying printing inks (remove any surface drying inhibitors before testing).
- Coated papers or foils compatible with sheet‑fed offset.
- Output stack simulation may use common office copy paper (80 g/m²); stack height above the test pair should be at least 5 cm.
- Evaluation: Visual inspection for reverse‑side yellowing and image‑wise gloss variation. Optical densitometry/colorimetry are noted as less reliable for these artefacts.
Applications
This method is practical for:
- Pre‑press and ink formulation teams assessing the compatibility of specific inks and coated substrates before production runs.
- Press and process engineers evaluating changes in ink film thickness, drying measures, or storage intervals to reduce ghosting risk.
- Quality control labs that need a repeatable laboratory procedure to reproduce and compare ghosting tendencies across materials and process conditions.
Benefits include enabling informed ink–substrate selection, guiding drying or finishing choices (e.g., lacquers that reduce visible ghosting), and providing a reproducible basis for troubleshooting print‑run defects.
Related Standards
- ISO 187 - Standard atmosphere for conditioning and testing of paper and board (conditioning requirements used by ISO/TR 12705).
- ISO 2834‑1 - Laboratory preparation of test prints; specifies the printability‑tester requirements referenced by ISO/TR 12705.
When reporting results, include a reference to ISO/TR 12705:2011 and document any deviations, tester settings, climatic conditions, ink and substrate designations, ink film thicknesses, time intervals, and the visual inspection outcome, as required by the Technical Report.