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Home / News / Industry News / Stirring Causes Foam, Spraying Causes Foam — How to Actually Eliminate It in Solventborne Systems
Industry News
Defoaming Technology — Solventborne & Solvent-Free Systems
Every stage of a solventborne coating's journey from production tank to cured film introduces air. Mixing and grinding entrain it mechanically. Thinning and let-down stir it in. Spraying atomises it directly into the wet film. Dip-coating drags it across the substrate surface. Without an effective defoaming system, the air introduced at each stage accumulates — and what cannot escape before the film sets becomes a permanent defect.
4
Stages where air enters the system
2
Functions: foam breaking + foam suppression
Where Foam Enters the Solventborne System
01
Production & Grinding
High-shear dispersers, bead mills, and mixing blades continuously introduce air during pigment grinding and let-down. At this stage, large amounts of foam can form quickly and persist for minutes — slowing production and making accurate viscosity measurement difficult.
02
Thinning & Colour Mixing
Adding thinners, hardeners, and colour pastes during formulation involves additional mixing that introduces air into a film-forming system that may already contain some entrained bubbles from production.
03
Spray Application
Spray atomisation generates significant turbulence in the wet film during deposition. Air is trapped between droplets and within the film as it builds. If not eliminated during the open time, this air causes pinholes and craters after cure.
04
Dip-Coating
In dip-coat processes, the substrate is withdrawn through the liquid surface — continuously dragging air against the forming film and creating foam at the air-liquid interface that must be broken before the coated part enters the oven.
DH-2044: Modified Polysiloxane Defoamer
DH-2044 is a modified polysiloxane defoamer developed for use in solventborne coatings and solvent-free epoxy systems. Its modified structure provides both active foam breaking — rupturing existing foam cells — and sustained foam suppression — reducing the rate at which new foam forms during continued processing and application.
Without Effective Defoaming
- Foam persists after mixing — slows production and extends takt time
- Residual bubbles in the wet film produce pinholes after cure
- Surface craters at burst-bubble sites reduce film smoothness
- Dip-coat surfaces show foam-related streaking or texture
- Film flatness and appearance inconsistent between batches
With DH-2044
- Foam broken during production — faster processing, accurate viscosity
- Suppressed foam carry-over into the applied wet film
- Fewer pinholes and craters — improved film surface quality
- Effective in dip-coat processes with continuous air introduction
- Improved film flatness and application consistency
System Compatibility
| Solventborne Coatings | Primary application — effective across aromatic and aliphatic solvent-based coating systems |
| Solvent-Free Epoxy | Specifically evaluated for high-solid, solvent-free epoxy systems where foam control is challenging due to higher viscosity |
| Production Stage | Can be added during grinding or let-down to address foam at the source |
| Application Stage | Maintains defoaming activity during spray and dip-coat application processes |
At what stage should DH-2044 be added — production or application?
For maximum effectiveness, it is best added during the grinding or let-down stage so that it is active when the largest volume of air is being introduced. A second partial addition at the application mix stage can address any additional foam from thinning and hardener addition.
Can it cause cratering if overdosed?
Like all defoamers, excessive dosage can lead to localised low-surface-tension zones that generate cratering. Evaluation at the recommended dosage range with a drawdown test is the standard approach before confirming the production addition level.
Is it also suitable for waterborne systems?
DH-2044 is specifically developed for solventborne and solvent-free systems. For waterborne applications, a waterborne-compatible defoamer chemistry is recommended to avoid compatibility and stability issues.
Key Takeaway
Foam in solventborne coatings is introduced at every stage from production to application — and what remains in the wet film becomes a permanent defect. DH-2044 addresses foam at both the production stage (breaking) and the application stage (suppression), supporting cleaner film formation across spray and dip-coat processes.
