I use the Personalizer to etch with and on a stainless blade I get a good deep, dark etch but my last two carbon blades are just barely etched into blade and not dark at all . I use the same bottle of solution on both stainless and carbon ( mostly stainless ) but I`m beginning to think they are not supposed to be etched with the same solution . What should be used on carbon ,if it is not the same ? Thanks