The Importance of the Coating Inspector

FCS Concrete Repairs gives great importance to the role of its Coating Inspector.

Erik Quintero is a NACE Certified Coating Inspector and has an important role in FCS Concrete Repairs as both our Senior Project Coordinator and Coating Inspector.

As a NACE Certified Coating Inspector his role in FCS Concrete Repairs includes that of a Quality Control Technician responsible to observe, test, verify and report on the compliance of protective coatings application with the manufacturer’s and the project specification, if present, during the application of the coating as well as after the work is completed.

The Coating Inspector’s work begins prior to commencement of the job. He should have the following information:

1. the needs of the owner,
2. the skill level of the applicator,
3. the contract documents,
4. the coating systems to be applied.
5. All Specifications related to the work
6. All applicable codes and standards
7. The Manufacturers Product Data Sheets (PDS)
8. The Manufacturer’s Material Safety Data Sheets (MSDS)
9. Any drawings of area where work is being performed

There are a number of hold points to be observed:

Prior to Start of Work: Visual observation of the subject surface.

After Surface Preparation: Surface contamination and visual cleanliness.

Immediately Prior to Application of the Coating: Climatic conditions, materials inspection, observe mixing of the coating.

Following the Application of Each Coat: Dry film thickness, holiday testing, recoat time, coating cure.

Following the cure of the coating: Final inspection of dry film thickness, holiday testing.

Non-Conformance Reports should be prepared for serious issues.

Typical Inspection Equipment used by Coating Inspectors:

1. Electronic Relative Humidity Temperature Meter
2. Surface Temperature gauge – thermocouple type or Infrared Type.
3. Dry Film Thickness Gauge:
4. Type 1 Banana Gauge – Positest FM or equivalent with calibration plates or foils.
5. Type 2 Electronic Gauge –Positector 6000 or equivalent with calibration foils
6. Flashlight
7. Inspection Mirror or Boroscope
8. Magnifying Glass or digital microscope
9. Salt Testing Equipment (Conductivity or Chlorides)
10. Black light for Oil Contamination
11. Blotter Paper or clean white rag for testing air supply
12. Surface Profile
13. Test-Ex Tape & Spring Micrometer or Positectot RTR Probe (Replica Tape Reader)
14. Surface Profile Gauge – Positector SPG
15. NEW Positector RTRP Surface profile – Peak Density probe
16. Holiday Tester if appropriate for the project
17. VIS Standards appropriate for the project
18. Paint Thermometer
19. Optional – Blast Needle Gauge and Nozzle Orifice gauge
20. Optional – Camera if Appropriate for the project.

Measuring Relative Humidity and Dew Point in the Field

Many coating failures can be attributed to applying coatings when climatic conditions were not within specifications. When trying to determine Relative Humidity and Dew Point temperatures, an understanding of the wet bulb, dry bulb, relative humidity and dew point is useful in getting accurate values.

SSPC-SP 13/NACE No. 6 – Surface Preparation of Concrete

This standard gives requirements for surface preparation of concrete by mechanical, chemical, or thermal methods prior to the application of bonded protective coating or lining systems. The requirements of this standard are applicable to all types of cementitious surfaces including cast-in-place concrete floors and walls, precast slabs, masonry walls and shotcrete surfaces.

An acceptable prepared concrete surface should be free of contaminants, laitance, loosely adhering concrete, and dust, and should provide a dry, sound, uniform substrate suitable for the application of protective coating or lining systems. Depending upon the desired finish and system, a block filler may be required.

While many factors can lead to coating failure, perhaps the most common reasons are:

1. Inadequate Surface Preparation

It is important to understand that surface preparation has two components:

• Visible Cleanliness

• Invisible Surface Contamination: These are normally salts which primarily cause two problems: corrosion and osmotic blistering

2. Mixing and Thinning

Improper thinning, the wrong thinner, the wrong mixture, incorrect induction time or exceeding the pot life can all cause paint failures or a shorter life than the coating was designed for.

 Holiday (or Porosity):

Holiday or porosity testing is looking for voids in the coating or coating system that go to the substrate. For holiday testing to work requires two conditions:

1. The coating system must be nonconductive.
2. The substrate must be conductive.

Holiday testing works best on conductive metallic substrates but will also work with concrete but is not as straight forward as metallic substrates due to variations in concrete that affect its conductivity.

Tape Adhesion Tests

There are two basic types of adhesion tests:

The Tape (Peel) Adhesion Test will determine if the bond strength of a coating on a substrate is “Generally Adequate” and was designed specifically for use on steel substrates. Use on other substrates may not be consistent. It is not intended to determine high levels of adhesion.

The Tape (Tensile) Adhesion Test will determine the bond of a coating on a substrate, or cohesion of the coating or cohesion of the substrate. Adhesion tests are DESTRUCTIVE and generally should only be conducted if a problem is suspected.