Have any of you performed the Copper Sulphate test to check for the quality of the passivation process on stainless steel?

I ask becasue I have the kit and am performing the test right now.  So far I have no reactions; IE there are no visible copper deposits on the test surface.

It seems extremely simple, I just want to make sure it is reliable.  The manufacturer of the test solution says so, and I have the officail instructions and certificate of conformance for the product.

Just looking for any general input while I wait for the part to dry.

304 S/S material.

Thanks