Bottom Line Up Front: Hardware fails at the surface long before it fails at the core. When specifying any door or window hardware, state both the base material and the finish system with a quantified corrosion requirement: for example 'zinc alloy (Zamak) body, copper-nickel-chrome plated, EN 1670 class 4 (240h salt spray)' or 'grade 316 stainless steel, brushed satin'. Interior dry projects can use standard plated Zamak (class 2-3). General exterior work should be class 3-4 plated or stainless 304. Coastal and marine projects should be class 4-5, PVD-coated, or stainless 316. Write the test into the specification — a finish that cannot show a salt-spray certificate is a finish you cannot trust.
Every door handle, hinge, lock and window fitting is made from a base material and given a surface treatment. The base material supplies strength, castability and cost; the surface treatment supplies appearance and corrosion resistance. Get the combination wrong, and within one or two seasons exterior hardware develops the familiar constellation of defects: blistering under the plating, rust weeping from screw holes, black spotting on 'brass,' chalky white oxide on aluminum.
This guide explains the materials and finish systems used across quality door and window hardware, the test language used to specify them, and the practical rules that separate a hardware schedule that lasts twenty years from one that gets replaced in two.
Base Materials Compared
| Material | Used For | Key Properties | Typical Quality Tier |
|---|---|---|---|
| Zinc alloy (Zamak 3/5) | Lever handles, knobs, lock cases, window gear handles, hinges (cast parts) | Castability, smooth surfaces, takes plating well; lower strength than steel/brass | Mainstream |
| Brass (H59/H62, leaded) | Premium handles, cylinders, escutcheons, heritage hardware | Machines beautifully, warm tone, corrosion-resistant with finish; heavier cost | Premium |
| Aluminum (6063/6061) | Profiles, pull handles, window hardware, architectural levers | Light, strong in sections, anodizes and powder coats well; softer surface | Architectural |
| Stainless steel (304/316) | Exterior and coastal hardware, hinges, heavy pull handles, marine-grade fittings | Corrosion resistance in the alloy itself; harder to fabricate decorative shapes | Exterior/Marine |
| Carbon steel (CRS, plated) | Internal mechanisms, budget hinges and screws | Strong and cheap; rusts quickly if plating is thin or breached | Budget |
Two notes for specifiers. First, 'solid brass' on a product sheet does not guarantee solid-brass hardware — many handles are brass-plated Zamak. If solid metal matters, specify it and verify by weight and price. Second, stainless grades matter: 304 resists typical exterior corrosion; 316 (with molybdenum) is the marine standard. Unlabeled 'stainless' in budget hardware is often 201 or 430, which rusts in coastal air.
Finish Systems Explained
Electroplating (the Conventional Route)
Electroplating deposits metal layers from a chemical bath. Quality architectural plating builds layers: a copper undercoat, then nickel, then a topcoat of chrome, brass, bronze or other metal. The result is bright and smooth, but the protection is only as good as the layer thickness and the substrate preparation:
- What can go wrong: Thin plating, porous substrate, or moisture ingress at edges cause blisters and rust blooms — the classic failure of cheap 'chrome' hardware outdoors.
- How to specify it safely: Demand a defined plating system (e.g., Cu+Ni+Cr) and a salt-spray result, not just a color name.
PVD (Physical Vapor Deposition)
PVD deposits a hard ceramic-metal coating in a vacuum chamber — commonly titanium nitride (gold tones) or zirconium compounds (black, gunmetal, champagne, rose). Compared with plating:
- Far harder and more scratch-resistant (thin-film hardness in the thousands of Vickers).
- Chemically stable — does not tarnish or fingerprint as readily; color stays for years.
- Environmentally cleaner process with no liquid plating waste.
- Higher cost per piece — justified on exterior, coastal and statement hardware, especially matte black and gold, where plated finishes disappoint quickly.
Anodizing (Aluminum)
An electrochemical conversion that grows aluminum oxide from the metal surface. Architectural anodizing (AA10-AA25) produces 10-25 µm of oxide, dyed and sealed for bronze/black/champagne tones. The oxide is extremely hard and corrosion-resistant; it cannot peel because it is part of the metal. Anodized aluminum is the standard finish for aluminum profiles and aluminum hardware in architectural work.
Powder Coating
Electrostatically applied and oven-cured polymer. Used mainly on door and window profiles and larger hardware pieces. Thick, tough, available in any RAL color — but softer than anodize or PVD, and damaged edges can expose substrate.
Corrosion Classes: The Numbers Behind 'Rust-Proof'
'Rust-proof' is a marketing word; the engineering word is a corrosion class backed by a salt-spray test (ISO 9227 neutral salt spray, NSS). European hardware is graded by EN 1670:
| EN 1670 Class | Salt-Spray Hours | Suitable Environment |
|---|---|---|
| Class 0 | No requirement | Internal, dry |
| Class 1 | 24 h | Internal, dry |
| Class 2 | 48 h | Internal, humid (bathrooms, kitchens) |
| Class 3 | 96 h | General interior + mild exterior |
| Class 4 | 240 h | Exterior, coastal |
| Class 5 | 480 h | Severe coastal / marine / industrial |
Practical specification guidance:
- Interior doors and windows: Class 2-3 is generally sufficient for plated Zamak.
- Exterior hardware (any climate with rain or humidity): Class 3 minimum; class 4 preferred. PVD or stainless recommended.
- Within 1-3 km of salt water, or aggressive industrial air: Class 4-5, stainless 304/316, or PVD. Specify 316 for fittings in direct salt exposure.
- Pools, spas, tropical resorts: Treat as coastal — stainless and PVD throughout.
One caution: the salt-spray test measures the finish on a clean test panel, not the hardware's real-life edges, screw holes and scratches. A class-4 plated Zamak handle installed and scratched at the coast will still corrode at the scratch. Where the design life matters more than the finish color, stainless is the honest choice.
Popular Finishes and Their Real Durability
- Polished / satin chrome: Timeless, bright; good durability when properly layered. Shows water spots less in satin form.
- Satin nickel: Warm-neutral, very popular; plating quality varies widely — check salt-spray hours.
- Brass / antique brass and bronze: Heritage look; plated versions patina or fail unless lacquered or PVD. Solid brass needs maintenance or a good lacquer.
- Oil-rubbed bronze (ORB): Dark, textured; durability depends on the process — quality ORB uses a multi-layer PVD-like system.
- Matte black: The design favorite of recent years; only PVD or quality powder systems survive exterior use — cheap painted black hardware fades and rusts quickly.
- Gold / champagne / gunmetal: Almost always PVD for durability.
Matching Finishes Across the Hardware Set
Hardware reads as a system: a matte-black handle with chrome hinges and a brass lock cylinder looks broken. When selecting finishes, coordinate across the full set — hinges, handles, locks, cylinders, stays, and even window gear handles. Two approaches:
- Single-family finishes: One finish (e.g., satin nickel throughout) — safe, coherent, easy to source and re-order.
- Mixed-metal design: A deliberate pairing (e.g., black hardware on bronze-finished profiles) — needs a clear design intent and careful sourcing from one supplier who can guarantee color consistency across product lines.
Color consistency across batches and product lines is a real specification issue: 'matte black' from two factories rarely matches. Buying the complete hardware set from a single manufacturer — as GOJP supplies — removes that risk because all parts share one plating/PVD line and one QC standard.
Test Data to Request From Any Supplier
- Salt-spray report per ISO 9227 for the exact finish proposed, with hours tested and result.
- Plating / coating thickness (µm) for each layer where plated.
- Corrosion class statement (EN 1670 or equivalent) per component.
- Cycle tests for moving parts (hinges, handles, locks) — 100,000-200,000+ cycles for quality mechanisms.
- Adhesion and hardness data for PVD and powder finishes where relevant.
- Material certificates confirming alloy grades (e.g., 316 stainless, Zamak 5).
Common Specification Mistakes
- Specifying color without a finish system: 'Matte black' is not a specification; 'PVD matte black' or 'powder coated RAL 9005' is.
- Trusting 'stainless' without a grade: Confirm 304 vs 316 vs 430 by certificate.
- Using interior-grade hardware on exterior doors: The finish will fail in one season of coastal weather.
- Mixing suppliers and hoping colors match: Buy coordinated sets from one finish line.
- Ignoring the substrate behind the finish: A great PVD coat over cheap porous Zamak can still fail — quality control starts with the casting.
- Forgetting maintenance: Even stainless benefits from occasional cleaning; salt deposits left on hardware accelerate corrosion.
