Liquid Coatings Troubleshooter - Film Property

Liquid Coatings Troubleshooter - Film Property

 

Dirty or Seedy Finish

  • Unclean conditions of application.
  1. Dust in paint room.
  2. Dirt in air or paint lines of spray apparatus.
  3. Dirt on conveyors.

- Cleanliness. Rearrange equipment so that any spray dustfrom booth does not reach previously painted parts.

  • Improper solvent which tends to throw resin out of solution.
    • Use the proper recommended thinner.
  • Material has been subjected to extreme cold which tends to throw some particles out of the solution.
    • Allow material to reach 75°F before applying. If still seedy, consult your Diamond Vogel® representative.

Poor Adhesion

  • Certain types of metal such as galvanized iron, cadmium, and zinc are difficult surfaces to obtain proper adhesion upon.
    • If normal methods of metal preparation do not overcome adhesion difficulties, send full particulars, with samples of metal to your Diamond Vogel representative or to the Diamond Vogel Paint Co., Inc., 1020 Albany Place S.E., Orange City, Iowa 51041.
  • Unclean surfaces or excessive phosphate residues.
    • Clean carefully with a commercial metal cleaner/conditioner. Follow with adequate rinsing.
  • Sometimes the finish coat and the primer used are not meant to be used together, and the solvent in the finish coat practically lifts the primer from the surface. Even though film will dry and have good appearance, primary adhesion has been ruined.
    • Make sure that the recommended primer and finish coat are used together.
  • Overbaking, which accelerates loss of flexibility in the film.
    • Check oven and bake according to instructions.

Poor Inter-Coat Adhesion

  • Primer and enamel not recommended for use together.
    • Use properly recommended system.
  • Primer or previous coat dries too hard–or glossy–due to inherent drying quality or long aging prior to application of finish coat.
    • Roughen coating with sandpaper or steel wool. It may even be necessary to use a reducer of higher solvent strength in the second coat in order that a tooth can be obtained in the film.

Poor Flexibility

  • It is often difficult to differentiate between “lack of adhesion” and “brittleness” in evaluating film failures. Other than inherent brittleness or lack of adhesion in a finish, the cause for either difficulty will be the same.
    • See “Poor Adhesion”
  • Improper baking. If complete polymerization of film has not been effected, brittleness may follow.
    • Check oven operation and follow baking instructions.

Poor Hardness (Mar Resistance)

  •  Film not completely dried.
    • Allow for more complete air-drying or baking.
    • Water spotting may occur.
  • Coating was incorrectly catalyzed.
    • Make sure proper mixing ratio is followed.