Do fingerprints show up better on cold surfaces or warm ones? Your fingertips leave behind oils and sweat when you touch a smooth surface. The temperature of that surface may affect how clearly the print forms. You fill six drinking glasses with water at temperatures from 0 to 50 degrees Celsius. Once each glass reaches its target temperature you press a finger against the outside. After the glass cools you dust it with cocoa powder and lift the print with clear tape. The fingerprint from the coldest glass at 0 degrees is the sharpest. As the glass temperature rises the prints become less and less clear.