Color Performance in Polysiloxane Coatings

October 14, 2021

Many coatings can be tinted using universal colorant systems. This approach works well when many different types of coatings need to be tinted in a store or tinting center. In almost all these cases, the color performance is acceptable. However, tinting a coating containing a polysiloxane resin with a universal colorant system can produce less than desirable effects.

First, let’s start out by explaining why a polysiloxane coating would be used.

Coatings formulated using a polysiloxane resin are designed to provide improved durability versus straight epoxy, alkyd, polyurethane or polyester coatings. The polysiloxane resin in the formulation provides enhanced durability. This enhanced durability comes at a higher cost. However, these coatings are designed for applications such as marine or other protective applications where enhanced durability is a requirement. For these applications, the improved performance of these coatings is more important than price.

Polysiloxane coatings are promoted to be a better solution for those demanding applications, in part, because they have better properties leading to a longer service life. They are perfect for projects where labor may be costly or regular maintenance is prohibitive. Specifiers and contractors understand the value provided by a polysiloxane coating. So, there is an inherent sense that these coatings will be better than most other coatings for the application.

Now, imagine a contractor is applying a polysiloxane coating to a water tower, a ship, or an offshore oil rig and the color performance isn’t perfect. Maybe the coating needs to be touched up and that area has a different color than the rest. Or the coating is applied by roller and the tie-in area indicates color float. While color is not the primary reason a polysiloxane coating is being used, color control issues can lower the impression of the performance of the coating. A poor impression of the coating is not what you want from a coating that has a higher price point versus standard coating types and has higher expectations for performance.

As most formulators know, the various components in the coating can cause performance issues. 

To name a few, these performance issues can show up in many ways such as gloss reduction, blistering or fisheyes. Color control issues such as color float or flocculation are also ways that incompatibility may show itself. Universal colorants based on acrylic or aldehyde resins are well suited for many coating chemistries. But they don’t perform as well in polysiloxane coatings.

In polysiloxane coatings, universal colorants will show varying levels of flocculation or color float. These color issues indicate a level of incompatibility between the colorant system and the coating. The flocculation may not be noticed depending on how the coating is applied, but incompatibility still exists. If the coating is sprayed in one coat with no touch-up, the color will appear uniform, but it may not exactly match the desired color. If touch-up is required or the coating is applied using a different method, a color difference will be more noticeable to the trained and untrained eye.

Colorants based on a polysiloxane resin will have better color control because the resin used in the colorant is similar to the polysiloxane resin used in the coating. 

Similarity between the colorant chemistry and the coating chemistry will lead to reduced incompatibility and improved color control. Improved color control will lead to an improved perception of the coating and a strong perception of the coating’s performance will lead to future sales.

Chromaflo Technologies supplies the UCD® PS line of colorants that are based on a polysiloxane resin. The line of colorants was formulated specifically to improve the color performance of polysiloxane coatings. The polysiloxane resin used in the UCD® PS colorants will react in the final film and will maintain the durability of the coating. The product line has been available for over two decades and is made in North America and in the EU. For more information about the UCD® PS line, please contact your Chromaflo Technologies representative or visit for more details.

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