Specifying Washer Finishes: Eight Processes and Purchasing Requirements

A Finish Is Not Just a Colour

Surface treatment can affect appearance, corrosion protection, friction, dimensions and inspection. A purchase description that says only “zinc plated” is usually incomplete.

Eight Finishes Available for Quotation

RINGRHINO can quote black oxide, blue-white zinc, yellow zinc, hot-dip galvanizing, mechanical zinc plating, Dacromet, zinc-nickel alloy plating and Teflon coating. Availability for quotation does not mean every size, material and hardness can use the same process without review.

• Black oxide: post-treatment, rust-preventive oil/seal and storage
• Blue-white zinc: passivation, thickness, corrosion requirement and hydrogen relief
• Yellow zinc: coating system and corrosion criteria as well as colour
• Hot-dip galvanizing: clearance, flatness, coating thickness and process-temperature effects
• Mechanical zinc plating: thickness, post-treatment, dimensional allowance and inspection method
• Dacromet: coating system, environmental requirements, thickness and corrosion acceptance
• Zinc-nickel alloy plating: composition, passivation/sealing, pretreatment and hydrogen-relief conditions
• Teflon coating: coating specification, service environment, assembly requirements and acceptance method

Spring Washers Need Additional Review

GB/T 93 includes elasticity and hydrogen-embrittlement considerations. Electroplating should define hydrogen-relief treatment; hot-dip galvanizing requires an additional review of the material condition and retained spring properties.

Reference Material

These references support further review of the standard name, edition, dimensions and related technical conditions.

• China National Standards Open System: GB/T 93-2025Used to verify the current standard title, status, publication date, implementation date and public-text entry.
• China National Standards Open System: GB/T 93-1987Used to verify the withdrawal status, publication date and implementation date of the previous edition.
• China National Standards Open System: GB/T 96.1-2002Used to verify the title, status, publication date and implementation date. The platform does not publish the full text because the standard adopts ISO content.
• China National Standards Open System: GB/T 97.1-2002Used to verify the standard title, status, publication date and implementation date.
• China National Standards Open System: GB/T 852-1988Used to verify the standard title, status, publication date and implementation date. The official platform does not currently provide the full text.
• China National Standards Open System: GB/T 853-1988Used to verify the standard title, status, publication date and implementation date. The official platform does not currently provide the full text.