Does solder wick expire?

Yes. As the copper is exposed to the open air, oxygen and moisture in the air interacts and oxidizes the copper. This oxidation is most apparent by the color of the wick. The brighter the copper, the fresher the wick. Oxidized copper will darken like a dirty penny. The more oxidized the copper, the slower the wicking action. We generally recommend replacing wick after 2-years, but that can be longer or shorter depending on storage conditions. Keep the wick bag or can sealed for maximum product life. If you have wick that appears to be too oxidized to use, unroll around 6”, trim off, then test the remaining wick. The outside of the spool of wick becomes oxidized first.