May 19, 2021
Industrial coatings have many different uses. An industrial coating might be formulated for broad usage or maybe designed for a very specific niche application. It may be transparent to show the beauty of the substrate. Or it could opaque to hide the substrate.
Whatever the type of coating, the components used to create that coating are chosen for very specific reasons. Unless the coating is a clear coat, the coating will use some type of colorant. With so much effort going into choosing each component of the coating, it’s worth doing the same for your colorant choice.
All coatings will do at least one of two things:
Often, they do both. Whether you call it a liquid colorant or a pigment dispersion or a pigment paste or a tinter, ultimately you are referring to a paint component that provides a portion of the aesthetic value to the coating. Many times, terms such as colorants and pigment dispersions are used interchangeable. In this article, colorants will refer to liquid pigment dispersions and not dyes or dry pigments.
These colorants can be formulated in many ways with components that may or may not be fully compatible with your coating. Therefore, if you are not careful, your colorant choice could reduce the ability of the coating to provide its other benefit, protection of the substrate. Possibly, they may even provide an undesirable look or feel.
Pigment dispersions refer to a type of colorant containing dry pigment dispersed and stabilized in a liquid medium to provide consistency and ease of use. This medium could be based on resins or surfactants and could be solvent-based, water-based, or solvent-free. The pigment dispersions may or may not contain other additives to help stabilize the pigment dispersion. Each of the components in these colorants can have an impact on the performance of the coating. While you won’t know the exact components of any pigment dispersion, your colorant supplier will provide some insight. And this insight or any support you get from the colorant supplier will help you to make the best choice for your needs.
So, why is this important?
Let’s consider an example. Suppose you are producing a 2K polyurethane coating. The coating consists of two components that are combined before application. During the cure process of these two components, there’s a reaction between the polyurethane resin and curative that makes the final coating more durable. In essence, the molecular weight of the resin making up the coating film increases, which increases durability.
If you use a non-functional colorant system, the resin or additive package in the colorants will not react within the final film and, at high levels, could reduce the durability of the coating. By selecting the wrong colorant for the coating, you may have added something to the coating that can reduce the quality of your high-performance coating. This is contradictory to the reason why that high-performance coating was formulated.
In contrast, if you add a colorant system with the right characteristics, you’ll produce a high-quality coating that performs the way it was designed. The perceived value of the coating will remain intact. The customer will be happy and return to use your product again.
To produce an industrial coating that maintains desired properties when tinted, you’ll need the right colorants. Here are the factors to keep in mind when choosing a colorant system.
Finding a colorant system that is compatible with your coating system is the highest priority. There are many sub-factors that may affect the final choice, but choosing a colorant system that is either water-based, solvent-based or solvent-free will be the first step. You wouldn’t want to use a water-based colorant in a solvent-based coating. You wouldn’t want to use a solvent-based system in water-based coatings. While you might be able to get away with using one of these two types of colorant systems in a solvent-free coating, there are better choices.
Once you have this broad choice out of the way, then you need to consider other factors. You may need to decide whether you want to tint multiple coatings with the same colorant system or if you want to use the same resin technology in the colorant system as you have in your coating. In other words, are you looking for a universal solution or a more specialized solution? Each company and each formulator will decide what is the best solution for their coating.
If you want to tint multiple coatings, then a universal colorant system would be a better choice than a system designed for a specific type of coating. Universal colorants are formulated to be used in many different coatings and are expected to perform well in all of them. These types of colorants offer a great approach when tinting many coatings with the same colorant system in a point-of-sale environment. To achieve universal compatibility, the colorant components are chosen to provide the broadest compatibility possible.
However, compromises may be made to ensure acceptable performance in as many coating types as possible. Therefore, some level of durability might be given up when tinting with a universal colorant system. But that might be perfectly suitable for end applications such as general industrial finishes or certain industrial maintenance coatings.
If you want the chemistry of colorant system to be similar to the coating system, then a more specialized system would be employed. By being more specialized for certain coatings, the colorant system would only be used in a limited number of coating types. You might want an acrylic colorant for an acrylic coating. Or you may want an epoxy colorant for an epoxy coating.
By using a colorant system specialized for a specific coating type, the colorant system will complement the coating performance, creating a high-performing coating compared to a coating tinting with a universal colorant system. These types of colorants tend to deliver better coating performance, which makes it suitable for higher durability applications such as automotive or protective coatings.
As noted, different types of coatings could be used for different applications. Coatings for general use, automotive, flooring and other protective applications are formulated differently, and have unique needs in order to succeed. So, the end use requirements need to be considered when choosing a colorant system.
The stabilizing mechanism of the colorant can have an impact on performance of the coating film such as gloss reduction or surface leveling. Pigments used in pigment dispersions can impact performance such as lightfastness. Choosing a colorant system with the proper components is essential in determining whether your coating succeeds or fails for its intended application.
Coatings without a long service life don’t need to be formulated to last for years. If you are creating a coating used for identification such as field marking, the coating is only being formulated to last for a short period of time. Therefore, the performance of the colorant system is more for a short-term aesthetic purpose. In these cases, a low-cost colorant system that is based on a surfactant would be suitable.
However, there are coatings designed to provide protection as well as aesthetic value. Protective coatings serve primarily to protect the items they coat. The level of protection will be related to the end application and can even change within the end application. Automotive, coil, and marine coatings have more demanding performance requirements and will need a different type of colorant system versus an industrial maintenance coating.
Even within an application, there may be levels of performance where different types of coatings could be used. For instance, floor coatings for a homeowner’s garage or basement floor may differ from a floor coating for a production plant. In each of these cases, a different coating would be developed, requiring a different colorant system.
Finding the right colorant for an application is an art of balancing all the factors that will dictate its success.
The method of tinting will also influence your colorant choice. There are two primary methods or tinting:
These methods may require different tinting strengths, chemistries and rheology. There is also a third way of tinting through pre-blended color packs that are typically used on job sites. Colorant manufacturers will design each type of colorant for one or more of these tinting methods.
A POS colorant needs to be formulated for gravimetric or volumetric dispensing. These colorants will be pumped into a container of base paint through a dispenser. Therefore, the colorants are formulated to have rheological properties so they flow through the dispenser properly and remain stable within the canister.
These colorants usually come in a set. There are usually twelve colorants that are used to match most colors, although more than twelve colors are usually available within the same colorant line. In some cases, certain dispensers may have sixteen canisters and four additional colorants can be added to the set to provide colorants with different properties such as improved lightfastness or brighter hues. So, there is some flexibility in developing the POS system, but the colors used for this tinting application are relatively standard.
An in-plant colorant needs to be formulated for good stability since the container may sit unopened for months and may be used repeatedly once opened. These colorants also tend to have a higher pigment loading to help to ensure optimal performance and more efficient tinting capabilities. High pigment loadings mean lower colorant usage levels and less impact on the final coating. So, these colorants may not be formulated in the same way a POS colorant is formulated.
Since coatings are tinted in a plant rather than at the point-of-sale, the possibility of using a different colorant system for every coating is possible. The chemistry of the colorant system can be tied to the chemistry of the coating. For high-end coatings such as automotive or marine, performance of the tinted coating can be ensured by using a colorant system with similar design properties as the coating.
In-plant colorants may have many, many different color options. Because the paint manufacturer is not limited to the number of canisters in a dispenser, they can use unique colorants with special properties to expand the range of their coating products. For instance, they could incorporate infrared reflective colorants into the portfolio to produce “cool” coatings. Or they may use colorants with very durable pigments for extreme applications.
The third method of tinting is the use of color packs. Color packs are pre-blended colorants that contain multiple pigments blended to provide the final color in an easy-to-use package. These colorants are generally added at the point-of-use, such as the job site, into a clear or semi-clear coatings base. Since these colorants are designed to match the final color, no additional work is required to tint the coatings base. The color pack is added to the base, the coating is mixed, then it is ready to apply.
Color packs can be produced in a couple of different methods. Dry pigment could be milled together at the time the pigment dispersion is manufactured to produce the final color. Or the single pigment masstones can be blended after each pigment dispersion is made. Both methods have benefits and drawbacks, but they both produce the same type of finished product. Choosing this method of tinting is more of an extension of the methods of tinting a coating base rather than a third formulation approach.
Value will always be a consideration. Value can mean different things to different people.
Value to a procurement manager may mean the lowest price. Value to a formulator may mean acceptable performance in many coatings. Value to a production operator or QC technician may simply mean the product performs the same day in and day out, batch after batch. But there is always a comparison of cost versus benefit that is considered when value is determined.
There is usually input from multiple stakeholders within a company. When it comes to colorant choice, everyone’s input may need to be considered. But if you want the best performing tinted coatings that match the performance expectations of the end user, technical input should be at or near the top. Colorants can vary in price, quality and value. One stakeholder’s choice may differ from another’s. But it is important to remember, the quality you get out of a coating may be tied to the quality of your choice in colorant.
To determine the value of a colorant system, it should be a cross-functional decision. Procurement can’t be the sole decision-maker of what colorant system to use. Also, while technical input is very important, their choice must be balanced with the initiatives of the company as a whole. Therefore, a cross-functional decision between sales, technical, marketing, production and procurement may need to be employed. Each company will weigh the input from these groups differently based on their company culture.
There are many factors to consider when choosing a colorant system for your industrial coating. The success of an industrial coating relies on finding the right colorant for the job. However, the decision may be influenced by many stakeholders in the company.
To help with making this decision, the colorant supplier will have tools such as product sheets, starting point formulas, and other information that will assist in the decision-making process. The colorant supplier can also provide support in the use of their products to achieve a higher level of success of the tinted coating.