ERSA Metal Wool Dry Cleaner (Pack of 10) When using lead-free solders, there may be increased oxide formation on the surface of the soldering tip, which can very quickly lead to a black non-wettable release layer. The ersa dry sponges use a special spiral wool, which removes the attached passive layers well during dry cleaning. This increases the service life of the soldering tip. Dry cleaner made of metal wool for the storage stands 0A50, 0A52, 0A54, 0A56 and for holding dry cleaner 0A08M. Why is our dry sponge better than a conventional viscose sponge? Viscose sponges are slightly moistened for cleaning. Todays soldering tips are made of different layers of metal. If there is a temperature shock when cleaning the tip due to the damp viscose sponge, the metal layers also stretch differently. This may cause micro-cracks on the surface. This leads to higher wear, especially when working with lead-free solder, this attacks the vulnerable areas. Since no temperature shock happens with the dry sponge, this is the gentler solution