I used a bunch of these swabs on my various kitchen items (mugs, plates, bowls, pots, etc.) and none of them made the swabs turn pink but when a swab dripped some water into the sink, the water turned pink...which would indicate lead in the water or sink material. I put a swab into some tap water in a glass, mixed it around, and it turned the water a pale pink/purple. I tried this with filtered water and same result. There should not be any lead in my tap water. I became quite concerned. So I googled it and these swabs turn pink/purple/red if there is calcium or iron present. So I tested this out. I have calcium carbonate powder (for making homemade toothpaste) and I put some of the powder into some tap water and then put a swab in and it quickly turned purple. THESE SWABS ARE USELESS BECAUSE THEY TURN PINK/PURPLE/RED IN THE PRESENCE OF OTHER METALS BESIDES LEAD giving false positives. I returned them for a refund. Don't waste your money.