ASTM Subcommittee D01.44 on Traffic Coatings has recently approved a new standard, D 7377, Practice for Evaluating the Water Wash-Off Resistance of Traffic Paints, and is developing a proposed new standard, WK16700, Practice for the Determination of Drying Rate of Waterborne Pavement Marking Paints Using a Test Chamber. The subcommittee is part of ASTM International Committee D01 on Paint and Related Coatings, Materials and Applications.

New Practice Measures Paint Resistance to Hard Rain
 
Hard rain sometimes falls soon after traffic paint has been applied to a road surface. Subcommittee D01.44 developed D 7377 to simulate hard rain conditions to determine the water wash-off resistance of an applied traffic paint film. D 7377 can be used to compare conventional and fast-dry traffic paints as well as the latex binders used in them for their relative ability to withstand heavy rain soon after application on roadways.
 
“The test simulates a worst-case scenario where there is a torrential rainstorm within 15 minutes to one hour of application,” says Gregory Shay, chair of the traffic markings task group and technology manager, traffic latex, The Dow Chemical Company. State Department of Transportation offices and global agencies with responsibility for traffic paint qualifications and regulations will find the new standard useful, as will traffic latex manufacturers and traffic paint companies for product development and quality control.
 
While D 7377 has now been approved, revisions will be ongoing. The subcommittee is currently considering a revision as WK16701 to include testing under less severe conditions and at high humidity.
 
ASTM International standards are available for purchase from Customer Service (phone: 610/832-9585; https://www.astm.org/contact/) or at www.astm.org.

Proposed Standard to Measure Paint Drying Rate
 
Shay says that the subcommittee welcomes participation from all interested parties, particularly state Department of Transportation staff and liquid traffic paint makers, in all of its activities, including the development of WK16700, a proposed standard that is designed to conveniently measure the drying rate of waterborne pavement marking paints under practical conditions of high humidity that are frequently encountered during the striping season. “Humidity has a profound effect on drying time of traffic paint markings,” says Shay, who notes that the proposed standard can also be used to assess drying time at normal ambient conditions and that the test chamber described in WK16700 can be used to condition paint films for other tests that are conducted within it and outside of the test chamber.

While some laboratories have been running variations of this procedure for many years, Shay says that others do not have a test chamber or information on how to construct or use one. “There is a need to provide this information and to standardize and advertise the method for uniform testing by traffic latex labs, traffic paint labs and Department of Transportation labs that test traffic paints for qualification,” says Shay.

For further technical information, contact Gregory Shay, The Dow Chemical Company, Cary, N.C. (phone: 919/469-6789; shaygd@dow.com). Committee D01 meets Jan. 20-22, 2008, in Ft. Lauderdale, Fla. For membership or meeting information, contact Jeffrey Adkins, Technical Committee Operations, ASTM International (phone: 610/832-9738; jadkins@astm.org).

Release #7822