Coating Inspection Services

Coating inspection

Coating inspections or verification is a well looked-for and requested quality assurance evaluation use when edifices and new constructions are undergoing replacement or repairs of interior of exterior liners.

Coating inspectors are accountable for the execution and the recording of simple non-destructive evaluations of liquid coatings applied in any form into metal surfaces. There are several forms of coating inspection evaluations and they are called or referred to as:

  • Dry Film Thickness
  • Wet Film Thickness
  • Holiday Inspection
  • Syrface Profile Measurement
  • Environmental Readings for Coatingn Application
  • Dry Film Thickness

    One of the most serious or precise measurement in the coating production is Dry Film Thickness coating inspections. Dry Film Thickness inspections delivers critical information about the projected life cycle of the coating and confirms any violations with the International Standards. It is because of the influence and effect on the quality, process and cost that Dry Film Thickness is considered the most serious measurement in the coating production industry.

    Dry Film Thickness or mostly known as DFT is the measure of the applied coating over the surface. Even if the coating contain a single layer or a multiple layers. The coating must be cured (or completely dry) before DFT can be performed. The thickness of the coating is contingent to the form or way is was applied to the substrate.

    Wet Film Thickness

    There is also another way to measure the coating thickness. Coating thickness can be analyze immediately upon application on to the surface and that method is called Wet Film Thickness. It is performed with MIL Gauges, Notched Gauges and/or Step Gauges.

    Wet Film thickness testing is another outstanding method to measure for coating and quality control and it is also another simple form to evaluate and examine coatings. Wet Film thickness testing is an instant form to get an immediate response on the quality of the coating applied and will deliver information in the event improvements are needed during the application.

    The Dry Film thickness could be forecast by performing or using the Wet Film Thickness method. It could be calculated by using the solids to liquids ratio method (or volume solids content known by others). Utilizing the Wet Film Thickness method also assist in cost control by making sure the correct coating quantity or volume is applied to the surface, enough material is ordered, and correct protection for wear, corrosion and damage is obtained.

    Holiday Testing

    Another test method for coating inspections is Holiday Testing. It is applied when coatings are protected to identify improper breaks on the coating such as voids or pinholes. The test consist of submitting an electric circuit to find out if the flows complete the circuit. The test is mainly performed to find coating film breaks or gaps that are not voluntarily noticeable.

    Holiday testing is most used on buried structures, tank interiors, and vessels of chemical storage due to the critical maintenance of sufficient coating protection in destructive environments. Continuity testing is another common name for Holiday Testing.


    Testing Specs Mostly Used
    • ASTM D1212-91 Standard Test Methods for Measurement of Wet Film Thickness of Organic Coatings
    • ASTM D3276-15 Standard Guide for Painting Inspectors (Metal Substrates)
    • ASTM D4138-07 Standard Practices for Measurement of Dry Film Thickness of Protective Coating Systems by Destructive, Cross-Sectioning Means
    • ASTM D4414-95 Standard Practice for Measurement of Wet Film Thickness by Notch Gages
    • ASTM D4541-09 Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers
    • ASTM D5162-15 Standard Practice for Discontinuity (Holiday) Testing of Nonconductive Protective Coating on Metallic Substrates
    • ASTM D7091-13 Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic Nonconductive Coatings Applied to Non-Ferrous Metals.

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