Paint peel off issue

Good day Kalidass, welcome to QFO!

You do not mention what type of finish is being applied, or on what type of material, or for which industry. The definitive answers to your questions can be found in the users guides for the specific finish you are working with. If you do not have them, please request them immediately and use them to understand what your processes do/don't do to conform to their recommendations.

There are some consistent considerations. A sample of them includes:

• The base material may require an undercoat of primer, which tends to be just porous enough to provide a surface the finish solution can adhere to. Please consult the finish manufacturer, either directly or by their published materials for users.
  
• If an undercoating is needed, there may be a need to lightly abrade the surface of undercoating after it has cured. Please consult the finish manufacturer, either directly or published materials for users. Specific abrasion recommendations may be in the form of grit: 220, 320, 400 etc.
  
• Surfaces must be free of contaminants. The type of contaminant is directly related to the coating chemistry (dirt, dust, oil, grease and/or surface moisture) and what would inhibit the coating's adhesion to the surface. If an undercoat is sanded with a specific grit of sandpaper, disks, block or cloth, the dust needs to be removed with an approved method before the finish coat is applied. Depending on the type of finish used, there may be sanding required between color and clear coats; the means to remove that dust will be specified by the manufacturer.
  
• When painting, keep the area free of suspended dust through meticulous removal of surface dust before beginning the color and/or gloss coats, as well as air filtration in an enclosed booth or some other controlled means.

Surface finish is a specialty that seems complex until we learn the recommendations provided by the manufacturer. Some infrastructure controls may be needed, and process controls in order to keep the surface suitable to properly "grip" the coating (paint) with a smooth, visually pleasing appearance.

I hope this helps!