A water repellent’s performance can and should be evaluated prior to specification or product selection. There are standardized tests that can be conducted in laboratory and field environments to accomplish this.
Common lab tests are:
Measures the water vapor permeability of a substrate.
Measures the water penetration and leakage through masonry surfaces.
Field testing, however, is the most reliable way to measure performance under actual project conditions. The following are the most common:
RILEM II.4. During the test, a tube is affixed to the surface with putty. The tube is then filled with water to simulate wind-driven rain speeds up to 98 mph. Performance is considered acceptable when water absorption is reduced by 80% or more. (See videos).
Test Kits available here
ASTM C1601. Similar to RILEM II.4, this test is designed to measure water absorption through masonry surfaces and evaluate the ability of water repellents to reduce that absorption rate. During the test a plexiglass chamber is affixed to the test area and made both water and airtight. Water is then pumped through a water bar located at the top of the chamber with the concept being to create a sheet film of water over the entire face of the test area for a four hour period. The volume of water is measured and the water pressure is increased at intervals throughout the test period. At the end of the test the water is drained from the chamber and measured. The water that was pumped into the chamber that doesn’t come out penetrated through the surface.
