Leneta Company, Inc. 15 Whitney Rd, Mahwah, NJ, 07430 USA
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# Leneta Paper-Testing Inks

For Evaluating Mottle, Holdout and Porosity of Coated and Uncoated Papers

These testing inks provide a simple and rapid way of monitoring batch-to-batch variations in paper structure and porosity. Inks of both high and low penetrations are required because the penetration quality of the ink must be appropriate to the holdout of the paper surface being tested. Coated papers, being relatively high in holdout, require a high penetration ink to obtain a sufficiently strong color and mottle pattern. Uncoated papers, being low in holdout, require a low penetration ink to avoid excessively strong color that would overwhelm any mottle or holdout distinctions. Examples of test patterns obtained using the two inks, demonstrating their specialized nature are as follows:

Test Procedure: Spread the ink on the paper to be tested using a spatula or drawdown applicator. After one minute remove the ink by first scraping off most of it with a straight edge, then wiping away the remainder carefully with a clean paper towel. The resultant test pattern is characterized visually for mottle and porosity. To obtain an instrumental value for porosity, measure the CIE-Y reflectances, or the densitometer values, of the stained and unstained areas, then calculate:

Porosity Index (Holdout)/100 = Y unstained – Y stained/Y unstained = 10ΔD – 1/10ΔD

Where D = densitometer value and Δ D = D stained – D unstained

$Porosity&space;Index&space;(Holdout)\div&space;100&space;=&space;Yunstained&space;-&space;Ysustained&space;\div&space;Ysustained&space;=&space;10&space;\triangle&space;D-1\div10&space;\triangle&space;D$