How to Remove Solder Flux From a Copper Pipe

When you solder copper pipe, you must first apply flux to both the pipe and the fitting. The flux cleans the pipe and allows the solder to bond to the copper properly. After finishing the soldering process, you need to remove excess flux from the copper pipe. If flux stays in place, there is a good chance the copper pipe will eventually corrode which may lead to unnecessary damage.

Things You'll Need

• Rag
• Water

Instructions

1. Dampen a rag with cool water before soldering your copper pipe. Set the rag next to your work area for easy access.

2. Solder the connection. Grab the damp rag and immediately apply it to the soldered joint.

3. Wipe the joint around its entire circumference. As you wipe, use different areas of the rag to ensure you wipe all the flux off the pipe. This will ensure you remove all the excess flux from the copper pipe.

Tips & Warnings

• Remove the flux while the copper pipe is still warm from soldering. Once the pipe cools, the flux will harden and it will be much more difficult to remove.

• Flux left on the copper pipe will eventually lead to pipe corrosion and possible damage. Always remove excess flux after soldering.

References

• E.H. Williams & Sons: Soldering Copper Pipes
• Elkhart Products Corporation: Soldering and Brazing Copper Tube
• Wet Head Media: How To Work With Copper Plumbing Pipe

Resources

• Clear Water Store: How To Treat Copper Pipe Corrosion