ASTM D1465 Standard Test Method for Blocking and Picking Points of Petroleum Wax
4. Summary of Test Method
4.1 Paper test specimens are coated with the wax sample, folded with the waxed surfaces together, and placed on a blocking plate. The plate is heated at one end and cooled at the other end to impose a measured temperature gradient along its length. After a conditioning period on the plate, the specimens are removed, unfolded, and examined. The points of initial film disruption (picking point) and where 50 % of the specimen width is disrupted (50 % blocking point) are noted. The temperatures of corresponding points on the blocking plate are reported as the picking point and blocking point or blocking range.
5. Significance and Use
5.1 Blocking of waxed paper, because of the relatively low temperatures at which it may occur, can be a major problem to the paper-coating industry. For example, when the waxed surfaces in a roll of waxed paper stick together, upon separation the surface films are marred and the glossy finish is destroyed. The wax picking point and the wax blocking point indicate an approximate temperature range at or above which waxed surfaces in contact with each other are likely to cause surface film injury.
