However good a paint or organic coating looks, if it has not bonded well to the surface it will lift in a short time. The most widely used check in the field and in the shop is the cross-cut and tape adhesion test. The standard most often referenced in aerospace and industry is ASTM D3359.
What do the classes mean?
The result is classified by the area that has lifted. In the lattice (cross-hatch) method, 5B means no detachment at all and 0B means very heavy detachment. In the X-cut method the same logic is expressed as 5A to 0A. The customer specification decides which class is acceptable.
Related reading: What is a special process? · Supplying aerospace and industry in the Gulf · ERP for special-process companies
Common mistakes
- The cut not reaching down to the metal
- Using the wrong tape or old tape
- Pulling the tape slowly or at inconsistent angles
- Estimating the class by eye and not taking a photo
- Testing before the drying time has elapsed
Which of these is in your records?
Most of these mistakes slip past when records are read one by one by eye, and auditors look for them first. The real question is which one sits in your own records. Upload your test photo to NTB SpecPro and quickly see which points may carry risk, the likely reason and a suggestion.
NTB SpecPro paint inspection marks the detached area from a photo of the test zone, proposes the class and adds the result to the report. Final evaluation stays with your authorized quality personnel.
Prepared by NTB SpecPro process quality engineering; reviewed by an engineer holding the International Welding Engineer (IWE) qualification. Questions: info@ntbspecpro.com
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