The HemoCheck blood residue test kit is an all-in-one test that provides a result in 30 seconds. It is simple to interpret and indicates blood residue on instruments and surfaces down to 0.1 ug. To use the HemoCheckTM, simply swipe the surface of the item being tested, drop the swab in the activated indicator, wait for 30 seconds and check for color change. If the swab remains completely yellow, the surface is demonstrably clean. If any area of the swab turns green or blue, the surface harbors protein residue and should be more thoroughly cleaned.