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Home / News / Industry News / Leveling Agent Fixed the Orange Peel — Why Are There More Craters Now Than Before?
Industry News
Section 1 · Why Does Leveling Agent Improve Orange Peel?
After coating is sprayed onto the substrate, the film needs to go through a process of flow, spread, and cure. If the film's flow capability is insufficient during drying, the high-and-low undulations that form at the surface cannot be corrected in time — orange peel results. One function of a leveling agent is to help improve the flow and spread of the film surface, gradually reducing these small surface undulations. So after adding an appropriate leveling agent, the film is typically more flat. But the problem appears precisely here.
Section 2 · Leveling Agent Changes Surface Tension and May Amplify Cratering
Cratering and orange peel do not form by the same mechanism. When a zone on the film surface has a low-surface-tension substance — such as oil contamination, silicone-type pollutants, release agents, or other foreign matter — the surrounding coating may be unable to stably cover this zone. The coating shrinks away from the contamination zone toward the surrounding area, ultimately forming a noticeable depression — a crater. The leveling agent itself affects the surface tension of the film. If the selected leveling agent does not match well with the current resin system, solvent system, and contamination environment, it may further amplify local surface tension differences — reducing orange peel while increasing cratering.
Section 3 · Why Not Obvious Before, but Cratering Suddenly Appears After Adding Leveling Agent?
Because the original system may have been in a relatively stable state. Although the film's leveling capability was ordinary, the surface tension difference was not pronounced enough to form large amounts of cratering. After adding the leveling agent, the entire film surface state changes. If micro-amounts of oil, silicone oil, release agent, or equipment contamination are present at this point, the leveling agent may make the difference between these low-surface-tension zones and the surrounding film more pronounced. Problems that were originally hidden may be amplified. So sometimes it is not that the leveling agent creates the contamination — rather, it makes surface defects that were not previously obvious easier to manifest.
Section 4 · Leveling Agent Is Not Better When Stronger
Many formulation adjusters fall into a pattern: severe orange peel → increase leveling agent → orange peel improves → continue increasing leveling agent. But leveling agents have an appropriate addition range. Below it, leveling improvement is not obvious; above it, the original surface tension balance of the system may be changed, potentially bringing new problems such as cratering, reduced recoatability, and changed interlayer adhesion. Therefore, a leveling agent truly needs to find the right balance point — not the maximum addition level.
Section 5 · The Same Leveling Agent May Perform Completely Differently in Different Resins
The polarity of the resin, compatibility, solvent composition, and other additives all affect how the leveling agent migrates and distributes in the film. Therefore, a leveling agent that can very well improve orange peel in System A may cause cratering after switching to System B. This is why leveling agent selection cannot only look at "whether there is a leveling effect" — the degree of matching with the entire formulation system must also be considered.
Section 6 · When Cratering Appears, Don't Only Focus on the Leveling Agent
If craters noticeably increase after adding a leveling agent, the first step should be to determine where the craters come from. Key areas to investigate: substrate contamination → spray environment → equipment cleanliness → raw material contamination → additive compatibility → leveling agent dosage. Silicone oil, greases, release agents, and other low-surface-tension pollutants in the spray environment can very easily become the cause of cratering. If the contamination source is not resolved, continuously adjusting the leveling agent may only temporarily change the defect presentation — without fundamentally solving the problem.
Section 7 · A Truly Good Leveling System Finds Balance Between Multiple Properties
An appropriate leveling agent should not only make the film "flatter." It also needs to simultaneously consider: film appearance, cratering resistance, recoatability, interlayer adhesion, compatibility with the resin, and storage stability. Especially in industrial coatings, automotive coatings, and high-gloss coatings, simply pursuing an extremely strong leveling effect does not necessarily lead to a better final film.
Summary
When leveling agent resolves orange peel but cratering worsens, the reason is often that the surface tension balance of the film has changed. While improving film flowability, the leveling agent also changes the surface state. If the formulation contains low-surface-tension pollutants, or the leveling agent does not match the resin system well, it may amplify local surface tension differences — increasing cratering. Therefore, this type of problem cannot be simply understood as "too much leveling agent added," but should be investigated from leveling agent type, dosage, resin system, and contamination sources together. Good leveling is not about making leveling as strong as possible, but finding the right balance between film flatness and surface stability.
Frequently Asked Questions
If orange peel and cratering are both present, which should be addressed first?
Eliminating contamination sources should come first — before any additive adjustment. If cratering is caused by surface contamination (silicone, oil, release agent), addressing the leveling formulation will not resolve it and may change the defect presentation without improving the underlying cause. Once the spray environment and substrate are confirmed clean, the leveling-cratering balance can be optimised through additive type and dosage selection.
Is non-silicone leveling agent less likely to cause cratering than silicone-type?
Non-silicone leveling agents typically have less dramatic surface tension reduction than silicone types — which means they are generally less likely to amplify cratering caused by surface contamination. However, even non-silicone types can cause cratering if overdosed or incompatible with the resin system. The choice of leveling agent type and dosage should both be evaluated together for the specific system and application environment.
