Measurement methods for controlling silver metallic ink film thickness

In this research a number of measurement techniques for silver metallic inks are evaluated. As no specific instrumental method for the measurement of these inks exists, a glossmeter, a spectro-densitometers, and a conventional densitometer were evaluated for their ability to measure the output of a press run where the amount of silver metallic ink was varied gradually from miniscule to large amounts of ink metered by the ink feed system of an offset lithographic press. A regression analysis was made to determine which of the metrics used in the study correlates best with physical amounts of metallic ink. Results will be presented to show the correlation between ink amount and gloss at 200, 600 and 750, density via spectral data, density via a conventional densitometer, and CIE L*a*b* measurements by a spectrophotometer. Data will be presented to show that gloss measurements have a poor correlation between varying amounts of silver metallic ink, whereas the L value of the CIE L*a*b* color space and all four filter channels of densitometers as well as densities convolved mathematically with status filter densitometry yielded good correlations with varying amounts of silver metallic inks.