The current study extends our earlier investigation on the real-time dynamics of print gap airflow around a single jetted drop over a moving substrate. In the present work, simulated web press printing was performed using a stationary grey-scale commercial inkjet print head to print full-width block of solid colour images onto a paper substrate with extended print gaps. The resultant printed images exhibit patterns or ‘wood-graining’ effects which become more prevalent as the relevant Reynolds number (Re) increases. The high-resolution scans of the printed images revealed that the patterns are created by oscillation and coalescence of neighboring printed tracks across the web. The phenomenon could be a result of drop stream perturbations caused by unsteady print gap airflow of the type similar to that observed in the previous study.
Wen-Kai Hsiao, Graham D Martin, Stephen D Hoath, Ian M Hutchings, Michael Hook, Mario Massucci, "Evidence of Print Gap Airflow Affecting Web Printing Quality" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP29), 2013, pp 303 - 306, https://doi.org/10.2352/ISSN.2169-4451.2013.29.1.art00011_2