Phenomenon: After the paint film is left outdoors for a period of time, the surface of the paint film will become discolored and powdered, and it will stick to the hand when touched.
(1) Improper coating formulation, using light-resistant resins and pigments; (2) Improper ratio of two-component coating curing agent;
(3) Internal coating
Phenomenon: Due to poor adhesion and bonding between layers of the paint film, ill-conditioned phenomena such as peeling, peeling, bulging, peeling of the paint film will occur.
Cause (1) The surface of the object is unclean and stained with oil, water, or other dirt;
(2) The surface of the coated workpiece is too smooth and the roughness is too small;
(3) Failure to match paint according to regulations;
Phenomenon: There are cracks with different shades on the surface of the paint film. If the lower surface can be seen from the crack, it is called "cracking"; if the paint film shows a small crack with a turtle pattern, it is called "cracking" .
Cause (1) The primer is not compatible with the topcoat, and the coating film is affected by external influences (mechanical
Phenomenon: There is a clear gap or matt between the surface of the coating film and the standard gloss of the paint itself, and the expected gloss cannot be obtained.
(1) The surface of the coating is rough and porous, and the oil absorption is large;
(2) Too much thinner is added and too little paint is sprayed;
(3) Adding wrong or curing agent to curing agent and diluent
Phenomenon: Bite bottoming means that the solvent in the upper coating softens and swells the underlying paint film, resulting in poor adhesion of the underlying paint film, which causes peeling and peeling. Coatings with strong solvents can bite the upper coating
Phenomenon: Also known as over-range spraying, it means that part of the coating has not reached the surface of the coated object and has become a paint powder, which then adheres to the wet coating, generates particles, is covered by subsequent coatings, or causes rough surfaces.
(1) Improper dilution ratio and excessive viscosity;
(2) Spray pressure
Phenomenon: The surface of the coating film is not smooth, and the state of unevenness is like orange peel. Reason:
(1) The paint is too thick and the diluent is too little;
(2) The spraying pressure is too high or the distance is too close, the amount of spraying paint is small and the distance is long;
(3) The temperature of the construction site is too high, the drying is too fast, and the paint cannot be leveled sufficiently;
(4) Operating environment wind
Phenomenon: Isolation of oil and shrinkage are local shrinkage on the surface of the coating film, as if water was sprinkled on the wax paper, and the spot-like appearance of the underlying layer is also known as fisheye, laughter, shrinkage, etc.
Cause (1) There is moisture, oil, or oily wax on the surface of the coated object
Phenomenon: When the paint film dries, round bumps of various sizes appear, also called blisters. Foaming occurs between the coated surface and the paint film, or between two paint films.
Cause (1) The paint viscosity is too high;
(2) Improper paint ratio;
(3) Oil stains, dust, and water bubbles are attached to the surface of the substrate
Phenomenon: On the coated surface or the groove, the paint flows. The uneven thickness of the paint film is formed. The severe ones are drooping like the paint curtain, and the light ones are like beaded tear marks.
Reason (1) Excessive diluent makes the viscosity lower than the normal construction requirements, and the paint can not fall and flow on the surface of the object;
(2) The temperature in the construction site is too low, the drying speed of the coating is too slow, and the fluidity is large in film formation;
(3) Spraying is uneven, and some parts are sprayed too thickly;
(4) The surface to be coated is unclean, and there is dirt such as oil and water, which cannot adhere well and flow after spraying;
(5) Dip too much paint at one time when brushing or roller coating, so that the thickness of the paint surface varies, and the thicker part will flow;
(6) The unevenness of the coated surface or the grooves of the corners, corners, and line angles of the object may easily cause uneven and thick coating
Phenomenon: The coating film contains water or other liquids, the color of the coating film is lighter than the original, and the coating film appears white mist.
(1) The ambient temperature is too high;
(2) High humidity in the construction environment;
(3) Water is mixed in the construction surface, container and paint;
(4) The diluent volatilizes too quickly;
(5) The bottom paint film contains
Phenomenon: After the coating film is dry, some or all of the coating surface has adhesion marks. Reason:
(1) Too much paint is added to the slow-drying solvent, and the solvent cannot volatilize;
(2) Insufficient or no addition of curing agent;
(3) The painted surface is contaminated and unclean;
(4) Sudden climate change during construction, rainy season construction, high humidity;
Phenomenon: After a period of time, the coating film is still not dry and does not harden.
(1) The coated surface contains moisture;
(2) Too little curing agent or forget to add curing agent;
(3) Use water-containing and alcohol-containing thinners;
(4) The curing temperature and time have not been reached, the humidity is too high, and the drying conditions have not been reached;
Phenomenon: The surface of the coating film is covered with dust, flying dust, foreign matter, etc .; the coating is applied on the surface of the object, and there are many particles in the coating film.
Main reasons (1) The construction environment is unclean, and dust, sand and other debris are mixed into the coating
Coatings form a coating after coating construction. Different problems of coatings after a period of service are called coating defects. The deterioration of the coating film quality during the use of the coating is a normal aging process; if the coating system is significantly faster than normally expected