Which method is considered a more precise way to measure soluble salts compared to visual inspection?

The Bresle Patch method is recognized as a precise technique for measuring soluble salts on surfaces, particularly before the application of coatings. This method involves using a self-adhesive patch that creates a sealed area on the substrate. A specific amount of deionized water is introduced into the patch, and through agitation, any soluble salts present on the surface dissolve into the water. After allowing for a specified contact time, the solution is analyzed, typically using conductivity measurements, to quantify the amount of soluble salts.

This approach offers a definitive quantitative assessment, which significantly surpasses the subjective nature of visual inspection. Visual inspection can only provide a qualitative understanding of contamination, often influenced by lighting and human perception, making it less reliable. In contrast, the Bresle Patch delivers empirical data that can guide decisions regarding surface preparation and coating application, ensuring better adherence to industry standards for surface cleanliness.

The other methods listed, such as the Sleeve Test, Alligatoring Test, and Moisture Meter, do not provide the same level of specificity in measuring soluble salts directly. They may be useful for their intended purposes but do not rival the precision and direct measurement capabilities of the Bresle Patch method in assessing surface contamination.