Does Coating Cause Fin Bridging on High-Density Fins?
Key facts
| Fin density | Approximate gap between fins | Bridging risk |
|---|---|---|
| 10 FPI | ≈ 2.4 mm | Low |
| 14 FPI | ≈ 1.7 mm | Moderate with thick films |
| 18 FPI | ≈ 1.3 mm | High with thick films; control drain-off |
| Microchannel louvers | Fine louver slots | High; thin film by dip only |
How bridging happens
When a coil is withdrawn from a dip tank, coating drains down the fins. Where fins are close together, surface tension can hold a film of liquid across the gap. If it cures there, the passage stays blocked.
How it is prevented
- Thin-film systems with low viscosity drain more cleanly.
- Controlled withdrawal at a speed that lets coating drain evenly.
- Air clearing of excess coating before cure where fins are dense.
- Orientation of the coil during drain-off so coating runs along the fins, not across them.
How it is checked
Both coil faces are inspected against the light after cure. Bridged areas are recorded, and the process is adjusted before the next coil.
What this means for your project
Tell us the fin density and coil depth with the enquiry. For 14 fins per inch and above, specify a thin-film system and ask for the bridging check in the batch report.
Gap values assume a fin thickness of about 0.1 mm.
Technically reviewed byPelagard Technical TeamCoating selection, application and quality controlLast reviewed:
