Rust Grades | Surfaces Preparation for Paint Application

Understanding Rust Grades

Rust is a common problem that can affect the integrity and appearance of metal surfaces. To help identify and assess the severity of rust, various grading systems have been developed, including BS 7079 Pt A, ISO 8501, and SS 05 59 00.

BS 7079 Pt A

BS 7079 Pt A is a British standard that defines the levels of rust contamination on steel surfaces. It uses a four-point scale, with Grade A representing the least amount of rust and Grade D representing the most severe rust contamination. The grades are defined as follows:

• Grade A: No visible rust
• Grade B: Light rust staining, up to 5% of the surface
• Grade C: Moderate rust staining, up to 15% of the surface
• Grade D: Severe rust staining, more than 15% of the surface

ISO 8501

ISO 8501 is an international standard that also defines the levels of rust contamination on steel surfaces. It uses a five-point scale, with Sa representing the least amount of rust and Sd representing the most severe rust contamination. The grades are defined as follows:

• Sa: No visible rust
• Sb: Light rust staining, up to 5% of the surface
• Sc: Moderate rust staining, up to 15% of the surface
• Sd: Severe rust staining, up to 50% of the surface
• Se: Very severe rust staining, more than 50% of the surface

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SS 05 59 00

SS 05 59 00 is a Swedish standard that defines the levels of rust contamination on steel surfaces. It uses a three-point scale, with Rp0.1 representing the least amount of rust and Rp2 representing the most severe rust contamination. The grades are defined as follows:

• Rp0.1: No visible rust
• Rp1: Light rust staining, up to 5% of the surface
• Rp2: Severe rust staining, more than 5% of the surface

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Understanding rust grades is important for identifying and addressing rust problems on metal surfaces. By using the appropriate grading system, you can assess the severity of rust contamination and take the necessary steps to repair and protect the surface.