While sanding the excess resin with micro from the rivet heads you have to be careful to not remove any aluminium from the rivet.
Removing just a tiny bit is done easily, I measured on a test rivet about 0.1/0.2 mm.
This doesn’t seem to be much but will it impact the strength of the rivet?
For educational purposes I did some shear and tensile tests with the 3.2 and 4.0 mm rivets.
With a digital kranescale of 300 kg I created this setup for the shear test:
Conclusion for the shear test: all rivets failed slightly above the shear values published by Gesipa and the rivethead height does not impact the shear strength of the rivet.
Conclusion for the tension test: all rivets failed slightly above the tensile values published by Gesipa. A height reduction of 0.1/0.2 mm does not impact the strength of the rivet. However when removing 0.2 mm or more it does impact the strength.