The SNAP organization (Specifications for Newsprint Advertising Production) provides guidelines and recommendations for optimal reproduction on newsprint substrates using cold-set offset lithography web presses. To assist the printing community to validate if new or augmented press equipment is capable of printing to the specification, SNAP publishes a "Lithographic Offset Press Acceptance Testing and Criteria for Acceptance" document that details:
Testing and press acceptance conditions
- Description of acceptance testing
- Suggested aim points and tolerances and
- Test forms and testing procedure
Controlled press testing was conducted on multiple cold-set newspaper presses using these procedures and an analysis is done to validate compliance of the empirical results with Item c: Suggested aim points and tolerances. In addition to presenting the actual results of press acceptance tests, a statistical approach is utilized to identify standard errors and new tolerances for cyan, magenta, yellow and black densities across three production sequences:
- Cold Start (initial press startup with presets)
- Mid-Production Speed and
- Full Production Speed
Verification research is conducted with the test data set from two cold-set newspaper presses located in different locales. Printed samples were collected during the press acceptance test run per the test protocol. The test and protocol is designed to replicate daily print production conditions.
The analysis indicates that mean printed Status T optical density of the data set falls within the SNAP aim values recommended for reproduction on newsprint substrates using cold-set offset lithography web presses. Additionally, a more reliable statistical approach that defines optimal press performance tolerances using standard error is provided as an addition to the +-0.05 Status T optical density tolerance currently published in the SNAP documents.