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Professional Zinc Alloy Surface Finishing Solutions

Golden Color Plating

Barrel Gold Plating — 24K, Rose, Champagne, Green & Light Gold

Precious metal barrel plating: 24K, light gold, rose gold, champagne, green gold. Gold salt concentration, free cyanide control, 0.1-0.5 μm decorative thickness. Cost management for small-batch gold salt.

Industrial roll plating production line with long gold plating tanks and orange overhead cranes.Conceptual illustration based on reference photographs; not test evidence.

Why Barrel Gold Plating

Gold gives the ultimate luxury finish — barrel processing makes it affordable for mass-produced small hardware

24K Gold

99.9% pure, luxury-grade finish

Color Golds

Light, rose, champagne, green gold

Decorative Thickness

0.1-0.5 μm — affordable luxury

Gold Salt Control

Precise dosing, auto-replenishment

Barrel vs Rack — Gold Plating Comparison

Cost and process differences between barrel and rack gold plating

ParameterBarrel PlatingRack Plating
Current density0.3-1.0 A/dm²0.5-2.0 A/dm²
Gold salt (as Au)1-5 g/L AuK(CN)₂2-8 g/L AuK(CN)₂
Free KCN10-20 g/L15-30 g/L
Temperature50-65 °C50-70 °C
Barrel rotation6-10 rpmN/A
Thickness typical0.1-0.5 μm0.5-5 μm
Gold usage efficiencyLower (drag-out loss in barrel)Higher (recovery easier)
Cost per part (0.1μm)Low (batch size spreads cost)High (per-part handling)
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Barrel Gold Plating — Process Steps

Luxury finish for mass-produced small parts

1Gold Bath Make-up

Gold solution based on gold potassium cyanide (AuK(CN)₂). Free cyanide maintains anode dissolution and prevents decomposition. pH and temperature precisely controlled.

Key Parameters
AuK(CN)₂ as Au: 1-5 g/L
Free KCN: 10-20 g/L
pH: 9.5-11.5
Temperature: 50-65 °C

2Barrel Loading & Gold Plating

Load base-plated parts (usually bright nickel) into barrel. Gold flashes in 30-120 seconds. Barrel rotation ensures uniform gold coverage. Low current density to avoid burning.

Key Parameters
Current density: 0.3-1.0 A/dm²
Time: 30-120 s
Barrel rotation: 6-10 rpm
Anode: Platinized titanium or stainless steel

3Color Formulation — 5 Gold Tones

Gold tone is adjusted by alloy composition: 24K (pure Au), light gold (Au-Ag), rose gold (Au-Cu), champagne (Au-Ag-Cu), green gold (Au-Ag-Cd or Au-Ag-Ni). Each has a specific bath formulation.

Key Parameters
24K (99.9% Au): Pure Au deposit, warm yellow
Light gold: Au-Ag alloy, pale yellow
Rose gold: Au-Cu alloy, 75-85% Au, pink tone
Champagne: Au-Ag-Cu, soft golden-pink
Green gold: Au-Ag-Ni, greenish tint

7Gold Salt Management (Cost Control)

Gold is expensive — precise control of gold salt in bath and drag-out recovery is critical. Auto-dosing by ampere-hour and drag-out recovery tank minimize gold loss.

Key Parameters
Gold cost: Track per batch (Au consumption = kAh × 0.3-0.8 g/kAh)
Drag-out recovery: Return rinses to bath or recovery tank
Auto-dosing: Peristaltic pump linked to Ah meter

5Anti-Tarnish Treatment

Gold doesn't tarnish, but the base metals in rose gold and green gold alloys can. Anti-tarnish dip (organic inhibitor or Cr³⁺) protects the alloy golds.

Key Parameters
Anti-tarnish method: Organic inhibitor 0.5-2%
Rinse: DI water only
Drying: 60-80 °C, 10-15 min

6Thickness Verification

XRF verification of gold thickness. Decorative gold 0.1-0.5 μm is thin — XRF must be calibrated for thin gold films on nickel.

Key Parameters
Thickness range: 0.1-0.5 μm
Measurement method: XRF (Au on Ni)
Batch sampling: 10 parts / 5000 pcs batch
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Gold Color Comparison Chart

All gold tones available for barrel plating

Gold TypeAlloyAu%AppearanceTypical ThicknessBest Use
24K GoldPure Au99.9%Warm yellow gold0.3-1.0 μmPremium jewelry, religious items
Light GoldAu-Ag90-95%Pale, soft gold0.1-0.3 μmCost-sensitive fashion hardware
Rose GoldAu-Cu75-85%Pinkish warm tone0.1-0.3 μmLuxury bags, fashion jewelry
Champagne GoldAu-Ag-Cu80-90%Soft golden-pink0.1-0.3 μmWatches, premium bags
Green GoldAu-Ag-Ni85-95%Greenish yellow tint0.1-0.3 μmFashion accessories, eyewear

📌 Gold Plating Cheat Sheet

AuK(CN)₂ (as Au)1-5 g/L
Free KCN10-20 g/L
pH range9.5-11.5
Temperature50-65 °C
Barrel current density0.3-1.0 A/dm²
Time (decorative)30-120 s
Thickness (decorative)0.1-0.5 μm
Gold color alloys5 types
💡 Gold cost calculation for barrel platingGold cost per batch = (Total Ah) × (Gold consumption rate, typically 0.3-0.8 g/kAh for 0.1 μm) × (Gold price per gram). For a typical barrel batch of 10,000 small parts at 0.1 μm Au, gold consumption ≈ 0.5-1.0 g. Drag-out recovery can save 20-30% of the gold salt. Use a dedicated drag-out tank after the gold bath and return the concentrated rinse back to the bath.

FAQ

What's the minimum gold thickness for barrel plating?
0.05 μm is technically feasible but risks pinhole coverage. We recommend 0.1 μm minimum for decorative consistency. At 0.05 μm, the base nickel color may show through on edges and corners.
Does barrel gold plate better on nickel or copper?
Both work, but nickel gives a brighter, whiter base that makes gold appear more vibrant. Copper base makes gold appear warmer (more reddish). For rose gold, copper base is preferred. For 24K and light gold, nickel base is standard.
How do I avoid gold thickness variation in barrel?
Three causes: (1) poor current distribution (use anodes on both sides of barrel), (2) insufficient rotation (increase to 8-10 rpm), (3) too many parts in barrel (reduce load to 50-60%). XRF check 10 parts from different barrel positions per batch.
What causes gold 'burning' in barrel?
Same as other metals — too much current for barrel geometry. Gold is especially sensitive because it's expensive (any wasted Au is lost). Keep gold current density at 0.3-1.0 A/dm². Above 1.5 A/dm² in barrel, expect brownish 'burnt' deposits that require stripping and re-plating.
Can you do REACH-compliant gold plating?
Yes — all our gold baths are cyanide-based (there is no practical non-cyanide gold bath for decorative plating). But waste treatment includes cyanide destruction before discharge. Gold itself is REACH compliant. For EU-bound orders, we provide full documentation.

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