When soldering a copper pipe joint that contains water, what is typically used to help dry the joint?

When soldering a copper pipe joint that contains water, it is essential to ensure that the joint is as dry as possible to achieve a successful seal. The use of bread in this scenario acts as a temporary plug to absorb moisture present in the joint. When inserted into the pipe, the bread expands slightly and helps wick away moisture, allowing the solder to flow properly and create a strong, leak-proof joint.

Using bread is a practical solution that plumbers have used for a long time. It is effective because it is readily available, inexpensive, and safe for plumbing applications. Once the joint is soldered and cooled, the bread can be easily removed, leaving the joint clean for further use. This technique minimizes the risk of contamination in the water supply, which could occur with other substances that might not be as suitable or safe to use in plumbing systems.

The other materials mentioned are not effective for drying out a joint for soldering in a plumbing context as they do not serve the same function as bread.