What should you do if the filler metal forms a ball instead of flowing?

When the filler metal forms a ball instead of flowing smoothly into the joint, the situation typically indicates that there are contaminants present on the surfaces to be joined. The presence of oils, oxides, dirt, or other residues can prevent the filler metal from wetting properly and spreading out to make a strong bond.

By inspecting for contaminants, you can identify and remove any substances that would inhibit proper flow. Cleaning the surfaces thoroughly before attempting to braze again is crucial, as this will allow the filler metal to make proper contact and achieve the desired joint integrity.

The other choices may not address the root cause effectively. Increasing heat might lead to undesired melting or damage without solving the underlying problem of contamination. Decreasing gas flow could lead to insufficient shielding from oxidation or other atmospheric influences, exacerbating the issue. Attempting to scrap and re-braze without first ensuring that the surfaces are clean may result in the same issue recurring. Therefore, recognizing contaminants and ensuring a clean surface is essential for successful soldering and brazing operations.