Dry Film Thickness Testing - What is it?
Measuring the dry film thickness (DFT) of a waterproofing membrane is crucial to ensure the membrane meets the specified thickness for effective protection usually recommended on the Product Technical Data by the manufacturer of the product.
Common Methods for Measuring Dry Film Thickness of Waterproofing Membranes
Magnetic or Eddy Current Gauges - Magnetic gauges work well on ferrous metal substrates (like steel). Eddy current gauges are used on non-ferrous metal substrates (like aluminum).These gauges measure the thickness of the dry membrane on the metal surface without damaging the membrane. Limitations: They only work on metal substrates and need a clean, smooth surface.
Ultrasonic Thickness Gauges
Can measure thickness on non-metallic substrates (like concrete) or thick membranes. Sends ultrasonic pulses through the coating and substrate to measure thickness. Requires calibration and sometimes a reference standard.
Micrometer or Caliper (Destructive)
A physical sample of the membrane is removed and measured with a micrometer.his is accurate but damages the membrane and is usually a last resort or for quality control of sample films.
Coating Thickness Gauge Calibrated for Membranes
Some advanced gauges are specifically designed or calibrated for waterproofing membranes.
Always verify calibration with manufacturer guidelines or test panels
Adehsion Testing - What is it?
Adhesion testing for waterproofing materials evaluates how well the waterproofing membrane or coating sticks to the substrate (surface) it's applied to, like concrete, metal, or wood.
Why it's important:
Strong adhesion is crucial to ensure the waterproofing layer doesn’t peel, blister, or delaminate, which would compromise the waterproof barrier and lead to leaks or structural damage.
Common Methods for Adhesion Testing
Pull-Off Test (ASTM D4541 or similar)
A metal dolly is glued to the waterproofed surface, and then pulled vertically until the coating or membrane detaches.
The force required to pull off the membrane is recorded as the adhesion strength (usually in psi or MPa).