What is the purpose of the milky stage of flux?

The milky stage of flux serves the specific purpose of indicating that the flux is ready for use in the brazing process. When the flux turns milky, it shows that it has sufficiently melted and activated, allowing it to effectively protect the joint area and prevent oxidation during the subsequent heating. This is a crucial stage as it can signal to the technician that the conditions are optimal for proper bonding to occur.

While preventing oxidation, sealing the joint, and promoting faster melting are important considerations in the overall brazing process, they do not specifically pertain to the unique indication provided by the milky stage of flux. Instead, the milky appearance directly correlates with the readiness of the flux, ensuring that the brazing operation can proceed effectively.