1. Importance of Surface Preparation

Surface preparation is a critical step in the coating process, directly affecting adhesion and durability. Proper preparation removes grease, dirt, rust, and other contaminants, providing a clean and uniform surface for coating application.

2. Grades of Manual and Power Tool Cleaning (St)

The grades of manual and power tool cleaning are denoted by the letter "St" and include the following:

St2 Thorough manual and power tool cleaning
When viewed without magnification, the surface should be free of visible grease and dirt, with almost no loosely adhering mill scale, rust, paint coatings, or foreign matter.

St3 Very thorough manual and power tool cleaning
Similar to St2 but more thorough, leaving the surface with a metallic sheen.

3. Grades of Blast Cleaning (Sa)

The grades of blast cleaning are denoted by the letter "Sa" and include the following:

Sa1 Light blast cleaning
When viewed without magnification, the surface should be free of visible grease, dirt, loosely adhering mill scale, rust, paint coatings, and contaminants.

Sa2 Thorough blast cleaning
When viewed without magnification, the surface should be free of grease, dirt, and nearly all mill scale, rust, paint coatings, and contaminants. Any remaining residues should be firmly adhered.

Sa2.5 Very thorough blast cleaning
When viewed without magnification, the surface should be free of grease, dirt, mill scale, rust, paint coatings, and contaminants. Any remaining traces should appear as slight discoloration in spots or stripes.

Sa3 Blast cleaning to visually clean steel
When viewed without magnification, the surface should be free of grease, dirt, mill scale, rust, paint coatings, and contaminants, leaving a uniform metallic color.

4. Conclusion

Choosing the appropriate level of surface preparation is crucial for ensuring coating performance. Different grades suit various coating requirements and environmental conditions. Understanding the characteristics and applications of each grade helps achieve effective surface preparation, enhancing coating quality and durability.