How Coating Leveling Agents Improve Surface Quality in Solvent-Based Coatings
8 min readA coating can contain the right resin, solvent, pigments, and additives, yet still produce an unsatisfactory surface if the liquid film cannot spread evenly during application. Uneven flow, differences in surface tension, and poor redistribution before curing may affect the final appearance and functional performance of the coating.
For solvent-based coating formulations, controlling the behavior of the wet film is therefore an important part of achieving a smooth and consistent surface. A suitable leveling additive can help the coating spread across the substrate more effectively while supporting surface slip and resistance to everyday contact.
Universal Coating Leveling Agent LD-9108 is a polyether-modified silicone additive developed for solvent-based coating systems. It is designed to reduce surface tension, promote leveling, and improve surface characteristics such as slip, mar resistance, and anti-rub performance.
Why Surface Tension Matters During Coating Application
Surface tension describes the forces present at the surface of a liquid. In a coating system, these forces influence how the wet coating interacts with the substrate and how readily it can distribute itself across the surface.
When the surface tension of a coating is not well matched to the substrate and formulation conditions, the liquid may have difficulty forming a uniform film. The result can be poor flow, uneven appearance, or localized surface imperfections.
A leveling additive works by modifying this surface behavior. By lowering and controlling surface tension, it can help the coating move and redistribute more efficiently before the solvent evaporates and the film becomes fixed.
However, reducing surface tension as much as possible is not necessarily the correct formulation objective. Excessive surface activity may create compatibility or appearance issues. The practical goal is to achieve an appropriate balance between leveling, compatibility, gloss, slip, and other required film properties.
How a Leveling Additive Supports Better Film Formation
During application, a liquid coating is constantly responding to differences in surface energy and tension. These differences can influence the way the film flows and settles.
A properly selected leveling agent can migrate toward the coating surface and adjust its surface characteristics. This can help the wet film spread more evenly and reduce the tendency toward an irregular surface.
For solvent-based coatings, this type of adjustment can be useful when the basic resin system already meets the formulation requirements but the finished surface needs additional improvement.
LD-9108 is formulated for this purpose. Its surface-active characteristics are intended to improve coating flow and leveling at a relatively low addition rate, allowing formulators to make targeted adjustments without fundamentally changing the resin composition.
Compatibility Is a Key Part of Additive Selection
Strong surface activity alone does not determine whether a leveling agent will work well in a particular coating. The additive also needs to remain compatible with the resin, solvent system, pigments, and other formulation components.
Poor compatibility can lead to unwanted changes in gloss, surface appearance, or coating stability. This is why a leveling additive should always be evaluated as part of the complete formulation.
LD-9108 is described as having good compatibility with various resin systems and is intended to improve leveling without unnecessarily compromising gloss or creating additional surface defects.
In practical formulation work, compatibility should be evaluated together with leveling performance. A useful test should examine the appearance of the cured film as well as the behavior of the wet coating immediately after application.
Low Dosage for Controlled Formulation Adjustment
The recommended consumption level of LD-9108 is approximately 0.1–0.5%. A relatively low dosage allows formulators to investigate surface improvements without introducing a large quantity of additional material into the coating.
The optimum concentration should not be treated as a universal fixed value. Different coating systems can respond differently depending on resin chemistry, solvent composition, pigment concentration, substrate, application equipment, and curing conditions.
Laboratory trials can therefore begin within the recommended range and gradually identify the concentration that provides the required balance of leveling and surface properties.
The additive can be introduced during different stages of production according to the formulation process, giving development and production teams flexibility when making adjustments.
Surface Slip and the Finished Coating
Leveling is only one aspect of surface performance. Once a coating has cured, the way the surface responds to physical contact can also be important.
LD-9108 can contribute to improved surface slip, which can give the finished film a smoother surface feel and reduce friction during contact with other materials.
This characteristic can be relevant to coatings that are frequently handled, stacked, transported, or exposed to contact during their service life. In such applications, a formulation may need both an attractive appearance and a surface with appropriate handling characteristics.
For this reason, the performance of a leveling additive can extend beyond the initial visual improvement of the wet coating.
Mar Resistance and Anti-Rub Performance
After a coating has been applied and cured, its surface may encounter repeated rubbing, handling, or contact with other objects. These conditions can gradually affect the appearance of the coating.
The product characteristics of LD-9108 include improvements in mar resistance and anti-rub performance. These properties can complement the leveling and slip effects of the additive, providing formulators with several surface characteristics to evaluate within one formulation adjustment.
Actual performance should always be confirmed using the appropriate test procedure for the intended coating application. Factors such as resin chemistry, curing conditions, film thickness, substrate, and mechanical contact can influence the final result.
Why Polyether-Modified Silicone Is Used
LD-9108 belongs to the category of polyether-modified silicone leveling agents. Silicone-based additives are commonly considered when a formulation requires controlled modification of surface properties.
The role of the polyether modification is important because surface activity needs to be balanced with compatibility. An additive that is highly active at the surface but poorly compatible with the coating may create unwanted effects.
The purpose of using a modified silicone leveling agent is therefore not simply to achieve the lowest possible surface tension. Instead, the objective is controlled surface modification that promotes better flow while maintaining the appearance and stability required by the coating system.
Physical Characteristics of LD-9108
For production and formulation teams, understanding the physical characteristics of an additive helps with dosing and processing.
LD-9108 is supplied as a colorless, transparent liquid. Its density at 25°C is approximately 0.85–1.0, with xylene used as the solvent and an active content of 15%.
These specifications can be taken into account when calculating the required addition quantity during laboratory development and production.
Because the recommended dosage is relatively low, accurate weighing and controlled mixing are important. Small changes in additive concentration may influence the surface behavior of the final coating, making repeatable testing especially valuable during formulation development.
Where LD-9108 Can Be Applied
LD-9108 is intended for normal-temperature solvent-based coating systems where surface leveling and appearance are important considerations.
When assessing the additive, formulators can prepare comparative samples using the same resin, solvent, pigment, substrate, application method, and curing conditions. One sample can serve as the control while another incorporates LD-9108.
The comparison can include:
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Wet-film leveling
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Final surface appearance
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Gloss
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Surface slip
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Mar resistance
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Anti-rub performance
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Resin compatibility
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Overall coating stability
This approach helps identify whether the additive is producing a useful improvement under the actual conditions of the coating system rather than relying on a single visual observation.
Practical Considerations When Troubleshooting Poor Leveling
Poor leveling does not always mean that the entire coating formulation needs to be redesigned. In some cases, the issue may be associated with surface tension, additive balance, substrate characteristics, or application conditions.
A controlled leveling-agent trial can help determine whether modifying surface behavior addresses the problem.
The most useful evaluation should look at both the wet coating and the fully cured film. If the additive improves wet-film flow but negatively affects gloss, adhesion, compatibility, or another important property, the formulation may require a different dosage or additive combination.
This makes step-by-step testing important when introducing a new leveling additive.
Product Packaging and Storage
LD-9108 is available in 25 kg and 200 kg plastic or iron containers. The additive should be kept tightly sealed and stored in a cool, dry environment according to the supplier's storage recommendations.
Under the specified unopened storage conditions, the stated validity period is one year.
Proper storage helps maintain the material in its intended condition before it enters the coating production process. Production personnel should also follow appropriate handling and dosing procedures during use.
About Yangzhou Lida Resin
Yangzhou Lida Resin Co., Ltd. was established in 1999 and focuses on the research, development, production, and sales of chemical additives and related functional materials.
The company operates production facilities in Jiangsu and maintains R&D and testing capabilities for product development and application evaluation. Its technical resources include an R&D center in Shanghai and a quality testing and application evaluation center in Yangzhou.
The company has more than 80 employees, with R&D personnel representing around 20% of its workforce. It was recognized as a National High-Tech Enterprise in 2022 and a Specialized, Refined, Differential and Innovative Enterprise in 2023.
Its product range extends beyond coating leveling agents to include coating additives, titanium coupling agents, aluminum coupling agents, boron and silicon coupling agents, and acetylacetonate salts. This broader product portfolio supports formulation development across different coating and chemical applications.
Evaluating LD-9108 in a Real Coating Formula
Every coating system has its own combination of raw materials and processing conditions, so laboratory validation remains essential.
A practical evaluation can begin by establishing a control formulation and then adding LD-9108 at several concentrations within the recommended 0.1–0.5% range. The samples can be applied under identical conditions and evaluated after the same curing period.
Key observations should include whether the coating spreads more uniformly, whether the cured surface has improved visual quality, and whether gloss and compatibility remain within the required specifications.
If surface slip, mar resistance, and anti-rub performance are also important for the final application, these properties can be included in the evaluation program.
This method allows the formulator to identify the effective dosage for the specific system rather than assuming that one concentration will perform identically across different formulations.
A Focused Approach to Surface Modification
Surface quality depends on more than the amount of coating applied. The interaction between the coating, substrate, and surrounding formulation components determines how effectively the wet film can spread and develop into a uniform surface.
A suitable leveling agent provides formulators with a way to adjust this behavior without necessarily changing the fundamental resin system.
With polyether-modified silicone chemistry, a recommended dosage of 0.1–0.5%, and functions covering leveling, surface slip, mar resistance, and anti-rub performance, Universal Coating Leveling Agent LD-9108 can be considered when developing or adjusting normal-temperature solvent-based coatings.
For coating manufacturers and formulation teams, the most effective approach is to evaluate the additive under real formulation conditions and balance surface improvement with compatibility, gloss, and overall film performance.
Through its additive manufacturing, R&D, testing, and application capabilities, Yangzhou Lida Resin Co., Ltd. provides a product platform for coating formulators looking to fine-tune surface performance while maintaining the core characteristics of their existing coating systems.
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Yangzhou Lida Resin Co., Ltd.
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