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Professional Zinc Alloy Surface Finishing Solutions

枪色电镀

Barrel Gun Color Plating — Black Nickel Ni-Sn / Zn-Ni Alloy

Gun metal / black nickel finish for barrel-processed small parts. Ni-Sn or Zn-Ni alloy, 5-level shade tunable. Wear-resistant, suitable for tactical gear, sports equipment and modern bags.

Why Barrel Gun Color

Gun color (black nickel) is one of the most requested fashion finishes for small hardware — barrel processing makes it cost-effective

Gun = Black Ni

Ni-Sn or Zn-Ni alloy, dark grey to black

5-Level Shades

Tunable from light gun to deep black

Industrial automated barrel plating production line with green rollers and yellow walkwayConceptual illustration based on reference photographs; not test evidence.

Barrel-Compatible

0.5-1.5 A/dm², slow rotation

Wear-Resistant

Taber test >500 cycles

Barrel vs Rack — Gun Color Comparison

Key differences in gun color plating between barrel and rack processes

ParameterBarrel PlatingRack Plating
Current density0.5-1.5 A/dm²1-3 A/dm²
Alloy controlBarrel rotation affects Ni:Sn ratioDirect current gives stable ratio
Color uniformityGood for non-critical surfacesExcellent overall
Throughput5,000-30,000 pcs/barrel200-1,000 pcs/rack load
Shade consistency batch-to-batchGood (ΔE ≤ 1.5)Excellent (ΔE ≤ 1.0)
Cost per partLowerHigher
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Barrel Gun Color — Process Steps

Creating 5-level tunable gun metal finish in barrel

1Base Layer Preparation

Gun color needs a bright or matte nickel base. The base brightness affects the gun color depth — bright Ni base gives more reflective gun, matte Ni gives deeper matte black.

Key Parameters
Base Ni type: Bright or matte
Base thickness: 5-10 μm
Base condition: Clean, active surface

2Gun Color Bath — Ni-Sn or Zn-Ni

Two alloy systems: Ni-Sn (60:40 to 50:50) gives classic gun metal. Zn-Ni (85:15) gives darker, more corrosion-resistant black. Both are barrel-compatible.

Key Parameters
Ni-Sn ratio: 60:40 to 50:50
Zn-Ni ratio: 85:15
pH: 4.0-5.5
Temperature: 45-55 °C
Current density: 0.5-1.5 A/dm²

3Shade Control — 5 Levels

Adjust color by changing current density, temperature and bath ratio. Level 1 (light gun grey) to Level 5 (deep black). In barrel, rotation speed also affects shade.

Key Parameters
Level 1-2: Low current, higher Ni content — light grey
Level 3: Mid current — standard gun metal
Level 4-5: Higher current, higher Sn — dark to black
Barrel rotation effect: Faster rotation = lighter shade

4Color Stabilization & Rinse

Gun color is reactive — rinse immediately after plating to 'freeze' the color at the target shade. Delayed rinsing causes shade drift.

Key Parameters
Rinse delay: < 10 s
Rinse type: DI water + stabilizer dip
Stabilizer: 0.5-2% organic inhibitor

5Sealing & Protection

Gun color needs a clear topcoat (e-coat or lacquer) for wear resistance and tarnish protection. Without it, gun color darkens unevenly with handling.

Key Parameters
Topcoat type: Clear e-coat or lacquer
Cure: 160-180 °C, 20-30 min
Final shade check: ΔE ≤ 1.5 vs master
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Gun Color Applications by Industry

Where gun metal finish is most requested

ApplicationShade LevelBaseTopcoatThickness
Tactical gear bucklesLevel 4-5 (deep black)Matte NiE-coat8-15 μm total
Sports equipment clipsLevel 3-4Bright NiLacquer6-12 μm
Modern bag hardwareLevel 2-3 (light-medium)Bright NiE-coat6-10 μm
Automotive interiorLevel 3-4Matte NiE-coat10-15 μm
Fashion jewelryLevel 1-2 (light grey)Bright NiLacquer5-10 μm
Furniture hardwareLevel 3Matte NiClear e-coat8-12 μm

📌 Gun Color Cheat Sheet

AlloyNi-Sn or Zn-Ni
Barrel current density0.5-1.5 A/dm²
Rack current density1-3 A/dm²
pH range4.0-5.5
Temperature45-55 °C
Shade levels5 (light grey → deep black)
Barrel rotation6-10 rpm
Wear resistanceTaber >500 cycles
⚠ Gun color shade drift is the #1 reject causeGun color is sensitive to every process variable: ±0.3 pH, ±2 °C, ±0.2 A/dm² all visibly shift the shade. In barrel lines, the added variable of barrel rotation speed makes consistency harder. Log ALL parameters every 30 minutes during gun color runs. Use sealed reference coupons stored in DI water between batches for visual verification.

FAQ

How do I maintain gun color consistency across batches?
Three rules: (1) Log pH, temp, current and barrel rpm every 30 minutes. (2) Keep a sealed reference coupon from the approved batch — compare visually before releasing. (3) Run a test coupon at the start of each shift before loading production. Color drift is easier to correct on test coupons than on 30,000 parts in a barrel.
Which alloy is better — Ni-Sn or Zn-Ni?
Ni-Sn (60:40) is the classic gun color, easier to control, more consistent. Zn-Ni (85:15) is darker, harder, and more corrosion-resistant but trickier to control in barrel. For most decorative applications, Ni-Sn is preferred. For tactical/military, Zn-Ni.
Can I match a customer's Pantone gun metal?
Yes — gun metal is one of our most-matched colors. Send a Pantone code (e.g., Pantone 426 C for deep gun, 432 C for medium gun, 429 C for light gun) or a physical swatch. We formulate and test to 5-level shade matching at ΔE ≤ 1.5.
Does barrel rotation speed affect gun color shade?
Yes — significantly. Faster rotation (12+ rpm) incorporates more oxygen and lightens the shade. Slower rotation (4-6 rpm) gives darker deposits. Calibrate barrel speed before starting a production run and maintain ±1 rpm throughout.
What is the wear resistance of barrel gun color?
With e-coat topcoat: Taber abrasion >500 cycles (CS-10 wheel, 500 g). Without topcoat: 100-200 cycles. The e-coat is essential for any wear-contact application (buckles, clips, clasps).

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