Couplant is required for sound waves to pass from an Ultrasonic Probe into material under test. Limited and inconsistent couplant application between probe and surface can impact on measurement results significantly. Defect sizing relies on a consistent couplant and known surface attenuation measurements.
Sonatest is concerned that it finds wallpaper paste is being used as a couplant material.
In the field Sonatest has found the use of wallpaper paste is wide spread and seen as alternative solution to formulated ultrasonic couplant. Sonatest will show via 'experimental evidence' that the performance of wallpaper paste as a couplant material is not as effective as a formulated ultrasonic couplant.
Wallpaper Paste can give more unreliable reading than purpose formulated ultrasonic couplant. Results will show a measurement inconsistent of over 1dB, which is equivalent to 8% variance at 80% screen height. Gain levels are impacted. It can also be shown to have a detrimental impact on the material surface.
Visit the Sonatest Ltd website for more information on Couplant V Wallpaper Paste