One of the keys to soldering with ease is to regularly clean the tip with a sponge or dry cleaner (gold curls). Burnt flux residues and oxide build up can drastically reduce the tip’s ability to transfer heat, and these contaminants can also act as a repellant to solder. Molten solder is actually the best ‘heat bridge’ between the iron and components, but the bridge won’t form unless solder can stick or cling to the iron tip. After a while holeless sponge surfaces can become dirty, making it hard to avoid picking up more contamination. Also, it sometimes be hard to scrape off stubborn debris on a flat surface. A hole in the middle allows used solder to fall away from the surface, and also provides an edge that can help in scraping off the tip. These particular sponges are 1.55 by 2.55 inches and can be easily cut to size before applying water.