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How can I get a good black or dark grey color in my waterborne epoxy coatings without pigment flooding or flotation problems?

Jim Reader
Lead Research Chemist

Pigment flooding or floating can occur when one of the pigments is not adequately stabilized and can separate from the mixture due to differences in mobility with the rest of the system. This effect often occurs in mixtures of heavier inorganic pigments
and fillers and smaller, lighter-weight pigments, such as carbon blacks. This effect is more common for the more intensely colored carbon blacks needed for dark colors. The effect can be difficult to control in two-component systems like waterborne epoxy formulations, where the pigment can be perfectly stabilized in one component, but loses stability when the two components are mixed together.

In such systems, specialized dispersants that can effectively stabilize these difficult carbon blacks and cope with the changes in pH and environment upon mixing of the resin and hardener are useful. ZetaSperse® 3100 pigment dispersing additive was developed especially for such pigments and can provide excellent performance in water-based epoxy formulations. ZetaSperse 2300 pigment dispersing additive is also proven to provide effective performance with many different pigments, including high tint strength carbon blacks.
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