What Does Acceptable Dry Film Thickness Range Mean?
Acceptable dry film thickness range is the value of a coating thickness that is within the minimum and maximum thickness set for each layer of cured protection coating. This measurement can be obtained from either destructive or non-destructive testing. When the value of the dry film thickness is within the acceptable range, it means that the coating should perform as expected, and the optimal coating strength has been achieved.
Corrosionpedia Explains Acceptable Dry Film Thickness Range
Acceptable dry film thickness is recommended by the coating manufacturer. It is employed to ensure that coatings offer results that are in accordance with the standards agreed upon by the International Organization for Standardization (ISO), the Society for Protective Coatings (SSPC), the American Society for Testing and Materials (ASTM) or any other relevant standards that dictate protective coating thickness.
Normally, the range is defined by two values: the maximum and minimum thickness. However, manufacturers sometimes specify a single dry film thickness value instead of recommending a thickness range. In this case, the maximum and minimum values of the coating thickness are determined by applying the SSPC-PA 2 procedure where the minimum value is 20% below the stated value while the maximum thickness is 20% above the stated value. The acceptable dry film thickness range is important because at the lower thickness, the coating may fail to offer optimal results.
The gauges used in measuring the acceptable dry film thickness range utilize magnetism, ultrasonic and electrical principles. Most of the measuring instruments are non-destructive, but in some tests destructive instruments are more effective.