Fasteners Finishes, Coatings & Platings

Interested in learning more technical information about fasteners? In our Fasteners Technical Data, you will find a centralized location of essential technical data about a wide variety of aspects all relating to fasteners.

Plating, Coating or Finish	For Use On	Degree of Corrosion Resistance	Characteristics
Anodizing	Aluminum	Excellent	Acid electrolytic treatment with frosty-etched appearance. Hard oxide surface gives excellent protection and reduced porosity. Tempered alloys can be dyed any color Type 1, Class 2. Good paint base and good for close tolerances parts.
Baking of Case Hardened Parts	Steel	Process to lessen hydrogen embrittlement	Electroplated fasteners which are case-hardened should be baked for a minimum of four hours within the temperature range of 375– 450°F no later than four hours after the plating process. This baking process does not guarantee that hydrogen embrittlement will not still be present after baking or that it will not occur at a later date while in service. Specialized testing or a substitute part may be required, depending on the application.
Black Nickel	All metals	Excellent	Generally used as a matching finish without lacquer coating.
Black Oxide	Ferrous metals and stainless steel	Good	A “conversion coating” which means it is formed by a chemical reaction with the metal to form an integral surface, as opposed to an “applied coating” which bonds with the metal. An oil finish is applied as a rust inhibitor. No risk of hydrogen embrittlement. An attractive black finish.
Black Phosphate	Steel	Very good	Standard finish on retaining rings, drywall and particle board screws. Color is dull black to a bright black appearance.
Black Phosphate and Oil	Steel	Very good	Standard coating on black phosphate. Non-drying petroleum oil is 1100 mg per sq/ft minimum. Oil serves as a rust inhibitor and a lubricant. Some fasteners with this plating call out required salt-spray test. Common fasteners include frame bolts, spring nuts, floorboard screws and Grade GT locknuts.
Black Zinc	All metals	Fair	A shiny black appearance with fair rust-resistance qualities.
Blue Polymer	Steel	Very good to excellent	Polymer is a barrier coating because it creates a seal around the fastener which resists corrosion and abrasion. A phosphate-zinc base is initially applied to the fastener, followed by the polymer which bonds to the sub-coating. Commonly used to coat and identify concrete screws.
Brass, Electroplated, Lacquered	Usually steel	Fair	Brass electroplated which is then lacquered. Recommended for indoor decorative use only.
Bright Nickel	Most metals	Excellent indoors. Good outdoors if thickness at least 0.0005 in.	Electroplated silver-color finish. Used for appliances, hardware, etc.
Bronze, Electroplated, Lacquered	Usually steel	Fair	Has color similar to 80% copper, 20% zinc alloy. Electroplated and then lacquered. Recommended for indoor decorative use only.
Cadmium, Electroplated (Waxed)	Most metals	Excellent	Bright silver-gray, dull gray, or black finish. Particularly effective corrosion protection, coloring and paint bonding. Good electrical conductivity quality. Not suggested unless absolutely necessary due to toxic content and extremely high cost.
Chromate (Clear)	Zinc and cadmium-plated fasteners	Very good to excellent	A secondary dipping process after plating increasing corrosion resistance, adding brilliance.
Chrome	Usually steel	Good	Chrome plating is applied in two methods. Hard-chrome deposits a thick layer of chrome on the fasteners. This gives the part a very hard finish and superior wear resistance but does not offer much protection to corrosion. A nickel-chrome finish is achieved by applying a flash of chrome on top of nickel plating. This process offers resistance to tarnishing and corrosion.
Chromium, Electroplated	Most metals	Good (improves with copper and nickel undercoats)	Bright blue-white, lustrous finish. Has relatively hard surface. Used for decorative purposes or to add wear resistance.
Color Chromate Finish	Steel	Very good to excellent	Olive drab, blue (used often for metric fasteners), bronze, red and other colors. A secondary dipping process after plating increasing corrosion resistance.
Color Phosphate Coatings	Steel	Superior to regular phosphate and oiled surfaces	Chemically produced color coating. Available in blue, green, red, purple, and other colors.
Copper, Electroplated	Most metals	Fair	Used for nickel and chromium plate undercoat. Can be blackened and relieved to obtain antique, statuary and Venetian finishes.
Dacrotized	Steel	Excellent and used for treated lumber	Dacrotized is a pollution free ceramic coating for screws used with treated lumber. Coating is comparable to the corrosion resistance of hot-dip galvanized fastener. Plating can typically withstand a 500-hour salt spray test. There is no risk of hydrogen embrittlement with Dacrotized plating.
Dichromate	Zinc and cadmium-plated fasteners	Very good to excellent	A secondary dipping in various colors such as yellow, brown, green or iridescent after plating increasing corrosion resistance and color finish.
Dull Nickel	Most metals	Same as bright nickel	Whitish cast can be obtained by mechanical surface plating or a special satin bath.
Electroless Nickel	Most metals and metalized plastics	Excellent	Electroless nickel is an auto-catalytic reaction used to deposit a coating of nickel on a substrate. Even coatings on parts surface can be achieved and flexibility in plating volume and thickness are advantages.
Hot-dipped Aluminum	Steel	Very good	Gives maximum corrosion protection. Dull grayish color. Requires thread size adjustment to permit ease of assembly.
Hot-dipped Tin	All metals	Excellent	Silver-gray color. Excellent corrosion, like electroplated tin, but thickness is harder to control. Plating is often used in the food handling industry because it resists organic acids.
Hot-dipped Zinc Galvanizing	All metals	Very good to excellent	Gives maximum corrosion protection. Dull gray in color. Requires thread size adjustments to permit ease of assembly. During the galvanizing process, steel reacts with molten zinc, forming layers of zinc-iron alloy layers which are metallurgically bonded to the steel surface. This hard barrier has a low corrosion rate and resists mechanical damage. Often specified for harsh environment.
Lacquering, Clear	All metals	Improves corrosion resistance	Used for decorative finishes. Color matched for color and lustre.
Lead-Tin	Steel	Fair to good	Silver-gray dull coating. Applied in hot-dip method. Helps lubricity.
Mechanical Plating	Steel	Very good	Dull gray with a smooth finish. Corrosion protection depends on coating thickness. Good coverage in recesses and thread roots. Mechanical plating reduces the risk of hydrogen embrittlement forming with the fasteners. Minimizes the need for the precautionary practice of baking the fastener soon after plating. This plating process is common for lockwashers made from spring steel to be plated this way to avoid brittleness after baking.
Passivation of Stainless Fasteners	Stainless steel	Very good	This process enhances stainless steel’s corrosion resistance. The fasteners are dipped in a solution which remove surface imperfections and produces a slight film on the surface of the parts.
Rust Inhibitors	All metal	Varies with type of inhibitor	Oils, solvents, greases, etc. Vary in color and film thickness. Used to protect fastener in transit and temporary storage.
Silver, Electroplated	All metals	Excellent	Decorative, expensive and excellent electrical conductor. It resists thread galling when mated parts are under extreme pressure or exposed to extreme heat.
Tin, Electroplated	All metal	Excellent	Silver gray in color. Excellent corrosion protection for fasteners in contact with food. Improves lubricity on steel fastener.
Wax	Most plated fasteners	Fair, used as a lubricate	Used for ease of assembly. Standard plating for thread rolling screws and locknuts.
Zinc, Electroplated (Clear)	All metal	Very good	Blue to blue-white color. Most popular of all commercial platings because it is relatively economical and offers good corrosion resistance in environments not subject to excessive moisture. Commercial zinc plating has a standard minimum thickness of 0.00015 inches. Class 2A thread allowances in sizes No. 8 and smaller may not accommodate this thickness. To avoid any reduction in the strength properties of these screw, a thinner coating may be acceptable.
Zinc & Green, Electroplated	Steel	Very good	Used for “grounding screws” in electrical applications.
Zinc or Manganese	Steel	Good	Black in color. Added protection when oiled with a non-drying petroleum oil containing corrosion inhibitors. Good lubricity.