Toolkits and equipment you need for coating inspection
Every stage of the coating process requires absolute control and inspection to make sure the coating eventually complies to given specifications. It all starts with inspecting the substrate and monitoring climate conditions, and ends with testing the coating film thickness (wet and dry) and surface properties. The testing and monitoring in different stages of the coating process are carried out with purpose-specific coating inspection tools and equipment.
Most important aspects to inspect after application
For a party, that applies coatings as an integrated part of a production process or service, the following aspects are the most important to inspect after the coating has been applied.
|Aspect to inspect||What to measure||Inspection tools|
|Film thickness before curing||Wet film thickness or thickness of powder before curing||Comb gages and wheels|
|Coating appearance||Gloss, reflection, opacity and surface structure (pinholes, orange peel, mottling etc.)||Gloss metres, haze metres, transparency metres, microwave scanners, DOI metres (Distinctness of Image)|
|Colour properties||Colour hue, colour impression under different viewing angles||Spectrophotometres, light booths, colour comparison cards|
|Dry film properties||Dry film thickness, adhesion, abrasion resistance and hardness||Digital and analog dry film thickness gages, microscopes, hardness testers, cross cut testers and other adhesion testers.|
Coating inspection tools for specific coatings
It is good to keep in mind that not every coating application requires same kind of inspection. Many coating inspection tool manufacturers also offer special tool kits made for the specific purpose.
Protective coatings inspection tools
When it comes to inspecting protective coatings, the emphasis lies on the protective properties enabled by an optimally applied coating. This means that anything that might harm the functioning of the coating, must be detected and the risk of coating failure eliminated.
Special tools to use: Protective coating inspection requires testing the wet film thickness; if the wet film does not suffice, the error can be taken care of while the paint is wet. The measuring can be done either with a comb or wheel which is often more accurate. Once the coating is dry, the dry film thickness must be measure; this is done with a (usually digital) thickness gauge. Other crucial aspects to test are adhesion and surface profile which may both affect the functioning of the coating. A multi functional surface profile gauge can be used for detecting pinholes and identifying orange peel, and adhesion is usually tested with an adhesion tester.
Montipower Test Equipment & Specialty Tool ElektroPhysik Wet film Wheel for increased accuracy of dry film thickness measurements
- PosiTest AT – A Automatic Pull-off adhesion tester
- Paint Test Equipment DC Holiday Detector uses high voltage technology to detect pinholes and other offsets in the surface profile
- PosiTest DFT coating thickness gage for all metal surfaces to measure the dry film thickness
Hazardous area coating inspection equipment
The coatings applied on hazardous areas are usually protective coatings and therefore, require similar equipment to those for protective coatings. However, the hazardous areas do not always allow the use of digital, electrically powered equipment, but require analogic tools. Therefore, visual inspection by the human eye is in a key position.
Special tools to use: To strengthen the accuracy of the visual inspection, the inspection toolkits often include magnifiers, microscopes and mirrors which make it possible to carry out coating inspection without electronics. The dry film thickness is inspected by using replica tape, and measuring the profile in the tape with an analogic thickness gauge. Adhesion is tested with a cross hatch cutter.
- Elcometer 211 Mechanical Coating Thickness Gauge for where electrical devices cannot be used
- Paint Test Equipment Cross Hatch Cutter to evaluate the resistance to adhesion (coating separated from substrate)
Automotive coating inspection
Automotive coatings have a protective and decorative role, which is why the key attributes to measure are colour consistency, gloss, surface profile and – properties.
Special tools to use: In the automotive industry the colour and gloss matter the most; these are inspected by using a spectrophotometre which defines the colour hue. Additionally, the surface profile can be assessed with a DOI meter which detects pinholes and orange peel. Last but not least the coating gloss can be defined with a gloss metre.
- Elcometer 456 Digital Coating Thickness Gauge