What is the reason why an inspector should avoid applying emulsifier with a brush?

The reasoning behind avoiding the application of an emulsifier with a brush revolves around the potential for the brushing action to prematurely mix the emulsifier with the penetrant. When emulsifiers are applied with a brush, the mechanical action can cause the emulsifying agent to blend with the penetrant before it has had an adequate opportunity to perform its intended function. This premature mixing can alter the effectiveness of the emulsifier, potentially leading to suboptimal results in the inspection process.

In contrast, a more gentle application method, such as spraying or pouring, allows for better control and timing in the application process. It ensures that the emulsifier can adequately interact with the contaminants without being immediately compromised by the mechanical action of the brush. This is crucial in scenarios where the quality and thoroughness of the inspection are paramount, as inadequate emulsification can lead to inaccurate inspection results.