Well, i do believe that i have heard a lot of people blow the dangers of using arsenic to stain keris a bit out of proportion. When taking proper precautions i think it is generally safe to use. That said i would never wash my keris in the kitchen sink where i do my dishes. I have a work sink in the basement where i do my clean up, but i do the actual work in a dedicated basin and try not to dump any substantial amount of warangan down even that sink because i do not want to add arsenic into the sewer system if i can help it. Your method does not seem cautious enough for me. Perhaps others will have a different opinion.
