ISO10605 Ed.3 / 6.4 Ground plane states: [When aluminum is used for the ground plane, care shall be taken to ensure that oxidation does not prevent a good ground connection.] How should the aluminum plate used during testing be maintained?

ISO10605 Ed.3 / 6.4 Ground plane states: [When aluminum is used for the ground plane, care shall be taken to ensure that oxidation does not prevent a good ground connection.] How should the aluminum plate used during testing be maintained?

We do not have specific expertise on this matter. However, because high-frequency noise such as ESD can be expected to flow as surface current rather than through the interior of the ground plane or horizontal coupling plane,
surface corrosion may impede the flow of noise and could affect the test results.
Therefore, oxidation should be prevented, for example by removing corrosion.

Note that ISO10605Ed.3 does not mention copper or brass.