After rubbing the surfaces, redness / purpled / mean the detection of lead Yellow mean not lead is detected Lead swabs provide immediate on most metal ceramics surfaces Including toy, woodworking, dishes, jewelry, bathtub glazes, ceramics, plumbing Lead swabs is very sensitive, result achieve in less than 30s Safe and green: swabs and package make from safe materials and not harmful to the human body Please do not put a swabs in your mouth Lightly dip the swabs into the water, not completely, after the swabs reach yellow color, use lead paint swabs to rub the surfaces, Manufacturer: sodeber