ASTM D7734/D7734M Open Time of Oxidative Printing Inks

Scope:

The ASTM D7734/D7734M testing for printing inks is important as it is critical to know the stay open time when creating printing inks and overprint varnishes that dry predominantly by oxidation so that premature drying does not occur. Other components of a printing press include rollers and other components.

Procedure:

In ASTM D7734/D7734M, a clearance gap is chosen that will result in a wet film thickness. A wide sample of the ink or overprint varnish is applied in front of the gap in the pulling direction with the applicator on the glass. The applicator’s sides are grasped with fingers and pressed down. A suitable amount of pressure is drawn down at a consistent rate. A timer is set for 1 hour.  The condition of the film surface is checked at the conclusion of each time interval by touching a fingertip to the film and then to an adjacent clean piece of glass next to the ink or overprint drawdown. When there is no ink or varnish transfer to the fingertip, the ink or overprint varnish film is deemed closed.

Video 01: Open time of latex paints

Result:
Results for ASTM D7734/D7734M testing are obtained from the open time of oxidative printing inks and overprint varnishes that are recorded during the test method.

Conclusion:

The ASTM D7734/D7734M testing for printing inks is important as it is critical to know the stay open time when creating printing inks and overprint varnishes that dry predominantly by oxidation so that premature drying does not occur.