Testing Water Resistance of Coatings Using Water Fog Apparatus
This standard practice covers the basic principles and operating procedures for
testing water resistance of coatings using water fog apparatus.
The test specimen shall be the sample of a final manufactured product of which quantity,
size, material and finish shall be agreed upon prior to testing. The specimen shall
be coated as per manufacturer’s instructions. There shall be a sample product with
a known paint durability to compare data along with at least two replicate specimens
of each different coating.
During the test a reservoir is filled with water that has been prepared by distillation,
continuous electrodeionization, ion exchange, reverse osmosis or a combination thereof
as per Type IV on D1193 - Table 1. The water shall be heated and maintained for
the duration of the test, whilst being circulated, to between 36°C - 40°C (96°F
- 104°F), if not specified otherwise prior to testing. The specimen shall be submersed
and supported in the testing unit at an angle of 15°. If multiple specimens are
being tested then all shall be freely exposed to the fogging and free from affecting
each other with a recommended minimum spacing of 30mm (1-3/16”). The fog is to be
collected from the nozzle by two containers within the testing unit. One shall be
close, within 10cm (4”) of the fogging nozzle and the other shall be as far away
as possible. The collection rates are recorded in mL/h and are measured every 24hrs.
After the specimen has been tested within several different section of the testing
unit and the atomizing air supply has been adjusted to allow for about 2.0mL of
water/hr to be collected then remove the specimen after a previously allotted timescale
then wipe dry and rate changes, if any. If possible, ratings should also take place
after the moisture has dried out of the specimen(s).