Now I applied a third layer with the damp microfibre, waited 10 minutes and buffed with a clean, dry microfibre cloth.
To make it easier to compare, I show the results above once more, along with the new thicknesses.
Wafer 1:
Thickness after first application: 22.7 nm
Thickness after 2nd application: 18.8 nm
Remeasured 24 hours later: thickness = 15.3 nm
Thickness after 3rd application: 22.1 nm
Wafer 2:
Thickness after first application: 20.6 nm
Thickness after 2nd application: 23.8 nm
Remeasured 24 hours later: thickness = 22.5 nm
Thickness after 3rd application: 17.0 nm
Wafer 3:
Thickness after first application: 15.9 nm
Thickness after 2nd application: 25.0 nm
Remeasured 24 hours later: thickness = 24.9 nm
Thickness after 3rd application: 20.1 nm
Wafer 4:
Thickness after first application: 16.9 nm
Thickness after 2nd application: 27.8 nm
Remeasured 24 hours later: thickness = 26.7 nm
Thickness after 3rd application: 21.5 nm
The results were a bit surprising; wafer1 gained, but the other three lost thickness!