Same paint, same spray gun, yet two people's spraying results are worlds apart — the difference lies in the spraying technique. Whether the gun movement is steady, the atomized flow is even, and the overlap is correct directly determines whether there will be runs, orange peel, missed spots, color difference. This article clearly explains the standard construction process and three core techniques.
In a nutshell: A good paint finish = steady spray gun handling (distance 15–25cm, even speed, 1/2–2/3 overlap) + choosing the right technique (wet coat/dry coat/fog coat); neither can be omitted.
I. Standard Spray Application Process
- Debugging:Adjust the air pressure, paint output, and fan pattern according to the coating, then do a test spray to check the spray pattern.
- First pass (mist spray/dusting): A thin layer establishes adhesion and reveals defects.
- Mid-coat / Basecoat: Apply by "wet-on-wet" or build up layer by layer with flash-off intervals.
- Clear coat: Final 1–2 passes of actual spraying to ensure gloss and thickness.
II. Three Core Techniques
| Technique | Characteristics | Application |
|---|---|---|
| Wet spray | High paint output, close distance, thick film | Solid color topcoat, clear coat |
| Dry spray | Low paint output, relatively dry, strong texture | Blending, color difference repair |
| Mist spray (dusting) | Extremely thin, scattered, only wets | First pass, blend feathering |
III. Three Key Elements of Spray Gun Movement
- Distance: Generally 15–25 cm; too close causes sagging, too far causes dry spray and roughness.
- Speed: Move at a constant speed, approximately 30–60 cm/s, avoid speeding up and slowing down abruptly.
- Overlap: Adjacent two courses overlap by 1/2–2/3 to ensure uniformity.
Application key points: Always keep the spray gun aligned vertically and perpendicular to the surface; move the wrist at a constant speed, do not swing with the arm; allow sufficient flash-off time between coats to avoid solvent trapped causing orange peel/pinholes.
Summary
Spray quality is jointly determined by process + technique + gun movement: first adjust the spray pattern, use fog spraying for the base, and wet spraying for the actual topcoat and clearcoat; keep the gun at a distance of 15–25cm, move at a constant speed, with 1/2–2/3 overlap. Choosing the right wet spray/dry spray/fog spray and allowing sufficient flash-off time will help you avoid sagging, orange peel, and lap marks.
Frequently Asked Questions (FAQ)
What is the appropriate spray gun distance?
Generally 15–25 cm. Too close results in excessive paint and easy sagging, as well as solvent streaks; too far and the atomized droplets dry before reaching the surface, forming a dry-spray rough finish. Follow the interval recommended by the coating and spray gun parameters.
How to distinguish and use wet spraying and dry spraying?
Wet spraying emits more paint and is done at a closer distance, used for solid color topcoats and clear coat full spraying; dry spraying emits less paint and is relatively dry with stronger texture, used for local blending and color difference repair. Fog spraying (dusting) only slightly wets the surface very thinly, used for priming and feathering.
What is the best overlap rate for gun passes?
Overlapping adjacent passes by 1/2–2/3 is most common, which avoids missed spots and obvious lap marks (banding). Insufficient overlap causes streaking, while excessive overlap leads to locally excessive thickness.
Why does orange peel occur?
Common causes include high coating viscosity, low or high air pressure, insufficient leveling time, and mismatch in thinner evaporation rate. Adjusting parameters and ensuring flash-off and leveling will improve it.
How long to wait between coats?
Depends on the coating type and ambient temperature and humidity, based on "touch-dry / dust-free" (usually a few minutes). Insufficient flash-off causes solvent retention, leading to orange peel and pinholes; excessive flash-off reduces intercoat adhesion.
Kexin New Materials · Automotive Coating Technology Library | This article is technical Q&A content, for reference in selection and application
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