A spring works under constant stress, which makes its surface far more critical than most people assume. A single corrosion pit can act as a stress concentration point and trigger fatigue failure long before the spring reaches its designed life. The right surface treatment protects against corrosion and wear, controls friction, and improves appearance. The wrong one can alter critical dimensions, change the spring rate, or even cause sudden brittle fracture.
This guide walks through the main surface treatments used on custom springs and, most importantly, when to choose each.
Springs are not static parts. They flex millions of cycles, often in humid, dusty, hot, or chemically aggressive environments. A good surface treatment addresses several needs at once:
The best choice depends on three things: the base material, the operating environment, and the precision and strength of the spring. Keep those in mind as we go through each option.
Zinc plating is the most common and economical corrosion protection for carbon and alloy steel springs. Zinc is sacrificial: it corrodes in place of the steel, protecting the wire even if the coating is scratched. A chromate conversion coating is usually applied on top — available in clear/blue, yellow/iridescent, or black — which adds further corrosion resistance and color.
Use it when: you have a cost-sensitive carbon or alloy steel spring used indoors or in mild outdoor conditions.
Watch out for: zinc plating is an electrolytic process and can cause hydrogen embrittlement on high-strength springs (see the dedicated section below). It also has limited high-temperature performance.
Nickel offers better corrosion and wear resistance than zinc, plus a bright, attractive finish. There are two types worth knowing:
Use it when: you need a harder, more durable, or more decorative finish than zinc — common in electronics, medical devices, and parts that must look clean and resist wear.
Chrome comes in two very different forms:
Use it when: wear resistance or a premium appearance is the priority.
Powder coating applies a thick, durable polymer layer that resists corrosion, chemicals, and UV, and comes in almost any color. It is tough and great for outdoor or industrial use.
Use it when: you have larger springs for outdoor, industrial, or aesthetic applications.
Watch out for: powder coatings are much thicker than platings, so they add meaningful dimension to the wire. They are generally not suitable for small precision springs or tight-tolerance parts, where the added thickness would shift the spring rate.
Passivation is not a coating — it is a chemical process that removes free iron from the surface of stainless steel and strengthens its natural chromium-oxide passive layer. Because it adds essentially no thickness, it preserves tight tolerances perfectly.
Use it when: you have a stainless steel spring (such as 304 or 316) for medical, food, marine, or chemical environments. In most cases a properly passivated stainless spring needs no additional plating.
Depending on the requirement, several other treatments are common in spring manufacturing:
This is where experience matters. Electroplating high-strength or high-hardness springs (roughly above 1000–1200 MPa tensile strength) can drive hydrogen into the steel during acid cleaning and plating. Under load, this can cause delayed brittle fracture — a spring that passes inspection but cracks days or weeks later.
There are two reliable ways to manage it:
If your spring is high-strength and will be plated, always call this out on the drawing. A manufacturer that does not mention hydrogen embrittlement on high-strength plated springs is a red flag.
| Treatment | Typical base material | Corrosion resistance | Adds thickness? | Best for |
|---|---|---|---|---|
| Zinc plating | Carbon / alloy steel | Good (better with chromate) | Slight | Economical, indoor/mild outdoor |
| Nickel (electroless) | Most steels | Very good | Slight, very uniform | Wear, complex shapes, electronics/medical |
| Chrome (hard) | Steel | Good | Moderate | Wear-critical, sliding springs |
| Powder coating | Larger steel springs | Very good | High | Outdoor/industrial, color, larger parts |
| Passivation | Stainless steel | Excellent (on SS) | None | Medical, food, marine precision springs |
| Anodizing | Aluminum / titanium | Good | Slight | Non-ferrous wire forms |
| Zinc-flake | High-strength steel | Excellent | Slight | High-strength springs (no embrittlement) |
Does surface treatment change a spring’s force or spring rate?
It can. Coating thickness adds to the effective wire diameter, and on small or tight-tolerance springs even a thin plating can shift the rate. Thicker coatings like powder have the biggest effect; passivation adds essentially none. Always factor the finish into the design on precision parts.
Which finish is best for stainless steel springs?
For most stainless springs, passivation is the right answer — it maximizes the corrosion resistance of the base material without adding thickness, and no plating is usually needed.
How do I avoid hydrogen embrittlement on plated high-strength springs?
Either bake the parts after plating to drive out hydrogen, or choose a non-electrolytic coating such as zinc-flake or mechanical galvanizing. Specify the requirement on your drawing.
Can you meet a specific salt-spray requirement?
Yes. Salt-spray performance varies widely by treatment and thickness, so just tell us the target hours (per ASTM B117) and we will recommend a suitable finish.
Choosing a spring finish is a balance of corrosion needs, tolerance, strength, and cost — and getting it wrong can cost you in field failures. At GL Springs, we have manufactured custom springs for the automotive, medical, electronics, industrial, and aerospace industries for over 20 years, and we are IATF 16949 certified with full in-house quality control.
Send us your drawing, specifications, and operating environment, and our engineers will recommend the right surface treatment and provide a fast, no-obligation quote. Free samples and 7-day sampling are available.
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