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definition
During the storage process, the paint deviates from its original color due to chemical or physical changes of certain components or chemical reactions with the container.
phenomenon
When the color paint bucket is opened, the color is often inconsistent.
The most common one is that the green paint turns blue after the bucket is opened, and some color paints are varnish after the bucket is opened, and the color of the multi-color paint appears to be suspended and so on.
the reason
(1) Some components in the coating react with each other, such as gold powder, aluminum powder and varnish will have an effect, lose the metal luster, the color will turn green, darken the com" href="">coating online coatingol.
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(2) The components in the paint react with the packaging iron drum.
For example, shellac paint will become darker in tinplate barrels, and the longer it is stored, the darker and darker the color will become; the nitrocellulose paint will turn brown in iron barrels.
Certain solvents (such as esters) are easily hydrolyzed and react with iron containers to darken the color, especially white paint.
(3) The density of the pigment in the multi-color paint is different.
The denser pigment sinks and floats lightly on it.
(4) The pigment in the paint undergoes a chemical reaction.
For example, blue paint or grass green paint containing iron blue, due to insufficient air in the container, iron blue has a reducing effect and is brown.
(5) When designing the coating formulation, there are problems between the compatibility of various resins and pigments and fillers, and the phenomenon of floating color appears.
Measures
(1) Paints that use copper powder or aluminum powder as pigments, because the free acid in the oil or paint has a corrosive effect on the aluminum powder and copper powder, the paint turns black and green.
Neutral paint can be used, and copper powder and aluminum powder should be added in the final stage of production; however, it is best to package the metallic pigment and paint in separate cans and mix them at any time during use.
(2) The packaging container should be galvanized or tin-plated iron drums, and some special varieties are best packaged in plastic or porcelain jars, glass bottles, etc.
Such as shellac varnish and nitro varnish should be dissolved and stored in a non-metallic container.
(3) When the color of the multi-color paint is inconsistent, stir it evenly and the color can still be consistent.
After stirring evenly, the color can be restored to the original color after contact with air, which is not a true discoloration.
(4) In the coating production process, avoid the mixing of moisture and appropriately extend the dispersion and grinding time.
At the same time, a small amount of wetting and dispersing agent is added to prevent color floating.
