Views: 28 Author: Site Editor Publish Time: 2021-03-25 Origin: Site Inquire
Adhesion Testing on Acrylic Mirror Coatings
Adhesion strength is an important target in evaluating the quality of the mirror coating layers. The traditional way of adhesion strength test is pull-off method and cross-hatch test. We normally use the second one. Cross-hatch cutter test is fast and simple to perform with a cross-hatch cutter test kit.
A lattice pattern is cut into the coating or back paint layers down to the mirror substrate, using a cross-hatch cutter. The test area is then brushed diagonally five times in each direction to remove any loose paint layer particles. A special tape for testing adhesion is then firmly applied over the cross-hatch test area and removed quickly by pulling the tape back off of the test area to reveal the amount of coating lifted off by the test tape. The cross-hatched test area is then visually compared to (ASTM) standards D3002 and D3359.
The test results were evaluated by varying degrees of coating pull-off from the cross-cut area:
Class 0 of adhesion (ASTM class 5B)：The edges of the cuts are completely smooth, none of the squares of the lattice is detached, no coating pull-off represents the highest level of adhesion.
Class 1 of adhesion (ASTM class 4B): A little coating falls off at the intersections of the cuts. A cross-cut area not significantly greater than 5% is affected.
Class 2 of adhesion (ASTM class 3B): The coating has flaked along the edges or at the intersections of the cuts. The affected cross-cut area is significantly greater than 15%, but not significantly greater than 15%.
Class 3 of adhesion (ASTM class 2B): The coating has flaked along the edges of the cuts partly or wholly in large ribbons. The affected cross-cut area is significantly greater than 15%, but not significantly greater than 35%.
Class 4 of adhesion (ASTM class 1B): The coating has flaked along the edges of the cuts in large ribbons, and/or some squares have detached partly or wholly. The affected cross-cut area is significantly greater than 35%, but not significantly greater than 65%.
Class 5 of adhesion (ASTM class 0B): Any degree of flaking exceeds Class 4.