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Paint morbid and response - discoloration reasons and preventi

2016.06.15   09:30

1, define

Coating in the process of storage, because the chemical or physical change of certain ingredients or react with container and deviated from its initial color phenomenon.

2, the phenomenon
Often appear when in open paint bucket color discrepancy, the most common is the green paint was blue after open barrels, also some paint varnish is after open barrels, multicolor paint a color suspension and so on.

3, Reason
Interactions between coating of some components, such as gold powder, aluminum powder and varnish, lose metallic luster, color green, dark.
Components of coating react with iron drum packing. Such as shellac varnish color will be deep in the tin bucket, the worse the longer storage color and black; Lacquer will turn brown in iron drum, etc. Some solvents (such as esters) easy to hydrolysis, react with the iron container, make the color darker, especially white paint is most obvious.
Multicolor paint pigment in different density, density of pigment sinking, light float on it. If use chrome yellow and iron blue with green paint, chrome yellow easy to sink, and iron blue floating in blue.
Paint pigment of chemical reaction. Such as contain iron blue of the blue paint or grass green paint, caused by a lack of air in the container, plays a role of reduction iron blue and brown. Iron and titanium white, and blue coating made of zinc oxide, lithopone, reduction occurred in the process of storage, etc.
Coating formula design, all kinds of problems between the compatibility of resin and fillers, floating color.

4, prevention and control measures
Do with bronze or aluminum powder paint coating, because the free acid in oil or paint corrosion of aluminum powder, copper powder, make the paint black hair green. Can choose neutral paint production, in the final stage to join copper powder, aluminum powder; But the best is to put the metal pigment and paint cans packaging, when using mix.
Packing container should choose zinc or tin tin barrels, some special varieties had better use plastic or POTS, glass bottle packing, etc. Non-metallic containers such as shellac varnish and nitrocellulose lacquer with dissolved and storage.
Multicolor paint color is not consistent, fully stir well, color still can resume. Classics agitate even, after it is exposed to air, color can restore color, do not belong to the real color.
In coating process, avoid water mixed with appropriate extension of the disperse milling time. At the same time to join a small amount of wetting dispersant, prevent floating color. Addition amount is commonly 0.2% ~ 1%, depending on the specific pigments dosage and varieties, the variety is commonly imported additives, such as silicone oil, polyacrylic ester, polymer poly (carboxylic acid salt, amino acid phosphate ester, fatty alcohol sulfate and so on.

                                                                                                                                                  By Nicole

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