304 - Black Zinc - Stainless steel - Cross recess pan head screw

Why Black Zinc on Stainless Steel?

At first glance, plating stainless steel might seem redundant—after all, 304 stainless is already corrosion-resistant. However, the black zinc finish serves a primarily aesthetic purpose. Standard 304 stainless steel has a bright, shiny silver appearance that can be visually distracting in certain applications. By applying a black zinc coating, we achieve a sophisticated dark finish while retaining the superior base material properties of stainless steel.

Material Breakdown

This product combines two layers of protection and functionality:

Base Material: Grade 304 (A2) Stainless Steel

The screw core is manufactured from AISI 304 stainless steel, containing 18% Chromium and 8% Nickel. This provides excellent resistance to atmospheric corrosion, humidity, and mild chemicals. Even if the black zinc coating is scratched or worn, the underlying stainless steel will not rust like carbon steel would.

Surface Finish: Black Zinc Plating

The black zinc layer is applied through an electro-galvanizing process followed by a black chromate conversion coating. This creates a uniform, matte dark grey to black appearance. The coating also provides an additional sacrificial barrier, though the primary purpose here is visual rather than protective.

Mechanical Properties

The screws maintain the standard A2-70 strength class of the 304 base material, with a minimum tensile strength of 700 N/mm². The thin plating layer does not significantly affect the mechanical performance.

Quality Assurance

We ensure both the base material and finish meet specifications. An EN 10204 3.1 Material Certificate verifying the 304 stainless steel composition is available upon request. Please note that third-party inspection services require an additional fee.

Ideal Applications

304 Black Zinc pan head screws are specifically chosen for:

• Audio & Video Equipment: High-end speakers, amplifiers, and home theater systems where silver screws would clash with dark enclosures.
• Professional Photography: Camera rigs and lighting equipment requiring a non-reflective finish.
• Architectural Hardware: Dark-finished door handles, railings, and fixtures in modern interior design.
• Medical Devices: Equipment housings where both aesthetics and corrosion resistance are critical.

Frequently Asked Questions

Why not just use carbon steel with black zinc?

Carbon steel black zinc screws are cheaper, but if the plating is scratched or wears off, the exposed steel will rust quickly. With304 stainless steel as the base, even if the black coating is damaged, the underlying material remains corrosion-resistant. This makes it a superior choice for long-term durability in demanding environments.

Will the black zinc coating wear off over time?

Like any plated finish, the black zinc layer can wear with repeated handling, friction, or exposure to abrasive conditions. However, for most static installations (where the screw is installed once and left in place), the coating will remain intact for many years. The key advantage is that even if wear occurs, the 304 stainless base will not rust.

Is this product suitable for outdoor use?

Yes, it can be used outdoors. The 304 stainless steel base provides excellent weather resistance. However, be aware that the black zinc finish may fade or develop a patina over time when exposed to UV light and weather. If maintaining the exact black color is critical for outdoor use, periodic inspection may be needed, or you might consider alternative coatings like black oxide on stainless steel.