Professional Zinc Alloy Surface Finishing Solutions

Gun Color Plating

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.

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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

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

Parameter	Barrel Plating	Rack Plating
Current density	0.5-1.5 A/dm²	1-3 A/dm²
Alloy control	Barrel rotation affects Ni:Sn ratio	Direct current gives stable ratio
Color uniformity	Good for non-critical surfaces	Excellent overall
Throughput	5,000-30,000 pcs/barrel	200-1,000 pcs/rack load
Shade consistency batch-to-batch	Good (ΔE ≤ 1.5)	Excellent (ΔE ≤ 1.0)
Cost per part	Lower	Higher

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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

Before

After

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

Application	Shade Level	Base	Topcoat	Thickness
Tactical gear buckles	Level 4-5 (deep black)	Matte Ni	E-coat	8-15 μm total
Sports equipment clips	Level 3-4	Bright Ni	Lacquer	6-12 μm
Modern bag hardware	Level 2-3 (light-medium)	Bright Ni	E-coat	6-10 μm
Automotive interior	Level 3-4	Matte Ni	E-coat	10-15 μm
Fashion jewelry	Level 1-2 (light grey)	Bright Ni	Lacquer	5-10 μm
Furniture hardware	Level 3	Matte Ni	Clear e-coat	8-12 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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Workshop Planning Data

Gun Color Plating — Data Zinc Alloy Finishing Managers Need

The automatic barrel plating line plates zinc alloy small parts with copper, nickel, tin and color finishes in batches of 50,000+ pieces, delivering uniform thickness and color at the lowest cost per piece.

650 m²Workshop Area

22 peopleTeam Size

260 kWInstalled Power

1.2-2.5M pcs/dayDaily Output (10 h)

Quality Inspection & Control

Check item	Method	Acceptance standard
Coating thickness	X-ray fluorescence / coulometric	Per spec: Cu 3-8 μm, Ni 3-10 μm, Sn 3-6 μm
Adhesion	Bend / peel / thermal shock	No flaking at 150 °C × 30 min
Color match	Colorimeter ΔE / master	ΔE ≤ 1.5 vs approved master
Salt spray	NSS chamber	12-72 h per finish spec
Pitting / roughness	10× inspection	No pitting, nodules or burnt deposits
Thickness uniformity	5 positions / batch	CV ≤ 10% across barrel load

Workshop Layout & Floor Area

Zone	Area
Automatic barrel line (12-16 tanks)	260 m²
Chemical storage / dosing	60 m²
Rectifier room	40 m²
QA lab + X-ray	50 m²
Dryer / centrifuge / sorting	80 m²
Rinse & waste treatment	110 m²
Utility & lockers	50 m²
Total workshop	650 m²

Manpower & Shift Plan

Role	Headcount
Line operators	10
Chemical technicians	3
QC inspectors (incl. X-ray)	3
Wastewater operator	1
Supervisor	1
Maintenance / electrician	2
Logistics & sorting	2
Total (2 shifts × 10 h)	22

Power & Utility Demand

Equipment	Demand
Rectifiers 12 V × 500-2000 A (4 sets)	80 kW
Tank heating + cooling	55 kW
Barrel drive motors (12-16)	24 kW
Pumps / filters / dosing	30 kW
Exhaust + scrubber	22 kW
Dryer + centrifuge	20 kW
Wastewater treatment	18 kW
Lighting & auxiliary	11 kW
Installed total	260 kW
Typical running load	≈ 205 kW

Production Flow Chart

PretreatmentPolish, degrease, activate

Alkaline CopperStrike layer for adhesion

Acid Copper / Nickel / TinBuild thickness + brightness

Color FinishGold, gun, black, antique etc.

Rinse ChainRecovery → counter-flow → DI

Dry & SortCentrifuge, inspect, pack

Daily Capacity — 10-Hour Operating Day

Parameter	Value
Batch cycle	25-45 min
Load per barrel	40-80 kg
Parts per batch	50,000-100,000
Batches per 10 h day	14-20
Daily output	1,200,000-2,500,000 pcs
Monthly output (26 days)	31-65 million pcs

Output Value Estimate

Parameter	Value
Plating fee per piece	USD 0.005-0.015
Daily output value (10 h)	USD 7,000-18,000
Monthly output value	USD 180,000-470,000
Annual output value	USD 2,160,000-5,600,000