Dear Ito san,
Regarding the SUS410, pls see the information as below.
1. Stainless steel WITH WAX, they will unable to be painted on head.(because it can’t be cohere.
2. WITHOUT WAX, the drilling speed will become unstable. Compare with screw WITH WAX, it will be around 30-40% divergence on 0.7 plate. But if the thickness of plate is less than 0.7, basically, there should be no problem.
According to the above, that is why we have to send you the sample for checking in advance, to check everything is meet your expectation.