QLQ zinc alloy surface finishing equipment and process QLQ zinc alloy surface finishing equipment and process

Professional Zinc Alloy Surface Finishing Solutions

Plating color

Barrel Plating — Antique Copper, Antique Silver, Black Patina & Custom Colors

Special-effect finishes for barrel: antique bronze, antique silver, black patina, colored e-coat overlay. 8 special colors + Pantone custom. ΔE ≤ 1.0 control.

Why Barrel Special Colors

Antique and special-effect finishes create distinctive vintage, modern and custom looks — made cost-effective through barrel mass processing

Antique Finishes

Oxidation + wipe + seal process

Black Antique Bronze

Deep aged look, vintage style

Hand holding a gold-colored aluminum profile with vertical grooves, displaying metallic finish and surface texture.

Colored E-Coat

Clear color overlay on plated base

8 Colors + Pantone

8 standard + custom ΔE ≤ 1.0

Why barrel special colours
Why barrel special colours - Antique and special-effect finishes made cost-effective by barrel mass processing.
Barrel plating workshop - antique and special-effect finishes are prod
Barrel plating workshop - antique and special-effect finishes are produced in mass batches, keeping cost per part low - QLQ workshop photo

Barrel vs Rack — Special Colors Comparison

How special-effect finishes differ between barrel and rack processes

FactorBarrel PlatingRack Plating
Antique finish consistencyGood — barrel tumbling gives uniform oxidationExcellent — individual control
E-coat color overlayGood for simple shapesExcellent for complex shapes
Part-to-part variationSlightly higher (ΔE ≤ 1.5)Lower (ΔE ≤ 1.0)
Throughput5,000-30,000 pcs/batch200-2,000 pcs/batch
Cost per special-color partLower (mass antique processing)Higher (individual handling)
Color depth/patina controlBarrel rotation time controls patinaManual application controls patina
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Barrel vs rack - special colours
Barrel vs rack - special colours - The same antique look behaves differently in each process.

Barrel Special Colors — Process Steps

Barrel special colours - process steps
Barrel special colours - process steps - Five controlled steps from base layer to sealed patina.

8 standard finishes plus Pantone custom colors — each with controlled oxidation and sealing

1Base Layer (Cu, Ni or Brass)

Most antique finishes start with a copper, nickel or brass base layer. The base metal determines the final antique color tone.

Key Parameters
Antique copper base: Cu or acid copper
Antique silver base: Bright Ni or Ag
Antique bronze base: Cu-Sn (bronze) alloy

2Oxidation / Patina Formation

Controlled oxidation with chemical patina solutions. Parts tumble in barrel with patina solution for 3-15 minutes. Barrel rotation ensures uniform oxidation.

Key Parameters
Patina type: Sulfide / selenide / permanganate based
Time: 3-15 min
Barrel rotation: 6-10 rpm
Temperature: 30-60 °C depending on patina

3Highlight Wiping (Barrel-Specific)

Highlight wiping in the barrel
Highlight wiping in the barrel - Controlled tumbling removes patina from high points only - the 'barrel antique' look.

In barrel, highlights are created by controlled tumbling with abrasive media — removes patina from raised surfaces, leaving depressions dark. This is the 'barrel antique' effect.

Key Parameters
Wiping method: Barrel tumble with fine media 5-10 min
Target effect: High points bright, recesses dark
Media type: Fine walnut / corn cob or soft plastic

4Sealing & Protection

Antique finishes are fragile without sealant. Water-clear lacquer or e-coat protects the patina from abrasion and color change from handling oils.

Key Parameters
Sealer type: Clear lacquer or e-coat
Thickness: 10-20 μm (e-coat)
Cure: Lacquer: air dry; E-coat: 160-180 °C

5Colored E-Coat Overlay

For custom colors: plate a neutral base, then apply colored e-coat (RAL, Pantone or custom). The e-coat provides uniform color and high durability.

Key Parameters
E-coat color: RAL / Pantone / custom
Thickness: 15-25 μm
Cure: 160-180 °C, 20-30 min
Color control: ΔE ≤ 1.0 vs target

6Color QC & Tolerance

Spectrophotometer check against master swatch. Antique finishes have inherent variation — we control it by limiting batch size and using calibrated patina solution.

Key Parameters
Tolerance (standard): ΔE ≤ 1.5 for antique finishes
Tolerance (e-coat): ΔE ≤ 1.0
Batch size limit: < 20,000 pcs per batch
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Plating line with controlled ventilation - oxidation, highlight wiping
Plating line with controlled ventilation - oxidation, highlight wiping and sealing are done in controlled baths - QLQ workshop photo

Available Special Colors

8 standard antique and custom colors we run in barrel

Color NameBase MetalPatina SystemFinishBest Use
Antique CopperCopperSulfide oxidationWarm aged copperFurniture hardware, retro designs
Antique SilverNickelSulfide + fine wipeAged silver lookCostume jewelry, decorative trim
Antique BronzeCu-Sn (bronze)Permanganate patinaDeep brown-bronzeDoor handles, vintage hardware
Black Antique CopperCopperHeavy sulfide + deep patinaBlack-brown aged copperTactical, industrial design
Aged BrassBrass or Cu + NiSulfide + selective wipeWorn brass effectFurniture, lighting fixtures
PewterNi-Sn alloyMatte finish + fine oxideSoft grey pewterModern minimalist hardware
Oil-Rubbed BronzeCu + dark oxideOil-based patina + sealDark, rubbed bronzePremium door hardware
Oxidized SilverSilver + sulfideControlled tarnishToned silverJewelry, vintage accessories

📌 Special Colors Cheat Sheet

Antique toleranceΔE ≤ 1.5
E-coat toleranceΔE ≤ 1.0
Patina time3-15 min
Barrel rotation (patina)6-10 rpm
Standard special colors8
Pantone customAvailable (ΔE ≤ 1.0)
Sealer (antique)Lacquer or e-coat
Batch size limit< 20,000 pcs
⚠ Antique finishes have inherent batch-to-batch variationUnlike precise alloy colors (gold, gun metal), antique finishes are chemically induced patinas that vary with: patina bath age, temperature, oxidation time, and barrel rotation speed. Even within a single batch, parts at the top vs bottom of the barrel can differ by ΔE 1-2. We control this by: (1) limiting batch size to 20,000 pcs, (2) pre-aging patina solution, (3) visual sorting under D65 light. Accept 5-10% shade variation as inherent to the antique look.
Semi-automatic barrel plating machine - 8 standard colours plus Panton
Semi-automatic barrel plating machine - 8 standard colours plus Pantone custom, colour difference controlled to dE 1.0 or better - QLQ workshop photo

FAQ

Can I get a consistent antique finish in barrel?
Antique finishes are inherently variable — that's part of their charm. Barrel antique finishes will never be as uniform as rack, but they have a more natural 'aged' variation that many customers prefer. For tight-tolerance antique, use rack. For cost-effective, naturally varying antique, barrel is perfect.
How long does the antique patina last?
Unsealed antique finishes darken over months as the patina continues to react. Sealed (lacquer or e-coat): 2-5 years indoors. Outdoor antique finishes need e-coat protection. We always recommend sealing antique finishes for any product that will be handled.
What's the MOQ for custom Pantone e-coat colors?
1000 pcs for standard RAL colors (stock tint). 5000 pcs for custom Pantone match (requires custom tint formulation, 2-3 weeks development, $200-500 tinting fee).
Can you match a physical sample (not Pantone)?
Yes — send 3-5 sample parts. We spectrophotometer the sample, formulate the patina or e-coat, plate a test batch, and adjust before production. Sample matching adds 5-7 days to the timeline.
Do colored e-coat overlays change the base metal feel?
E-coat adds a resin layer 15-25 μm thick. This slightly softens the 'metallic' feel and adds a glossy sheen unless a matte e-coat is specified. For true metallic feel with color, choose an alloy color instead of e-coat overlay.

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