Surface Preparation Before Applying Flux

Machining oil, grease, oxides and surface contamination can impair wetting and filler flow, increasing the risk of voids and incomplete joints.

Flux does not replace initial cleaning. Remove contamination and grease using a method compatible with the component, then remove oxides appropriately.

Surface roughness also matters. Very rough or highly polished surfaces can make proper joint filling more difficult. Match preparation to the material and surface condition.