Worried your current coating is hurting your compliance goals? I used to ignore the coating’s chemistry—until it cost me a major European client.
Zinc flake coatings are generally safer for the environment than Dacromet, mainly because they avoid hexavalent chromium and generate less hazardous waste.
Today’s buyers expect more than just corrosion resistance. You need coatings that meet REACH and RoHS, minimize emissions, and reduce compliance headaches. Let’s look at how these two coatings compare.
What are the disadvantages of Dacromet coating?
Looks good on paper—but risky in practice. That’s how I first felt after using Dacromet on a marine equipment project.
Dacromet often uses hexavalent chromium, which is toxic and restricted under global environmental regulations, increasing cost and compliance risk.
Why Dacromet Can Be a Red Flag in Modern Manufacturing
Dacromet is known for excellent salt spray performance, often exceeding 500 hours without red rust. But its chemistry includes hexavalent chromium (Cr6+). This substance is harmful to both workers and the environment. It’s tightly controlled in Europe and North America. That means special handling, employee protection, and waste treatment—all of which raise costs.
Aside from regulatory issues, Dacromet requires curing at around 240–300 °C. This uses more energy than low-temp or room-temperature processes. Overheating parts can cause warping or coating failure, which means scrap.
When I first offered Dacromet to a German client, they rejected it immediately because of RoHS restrictions. Since then, I’ve switched most parts to Cr-free coatings like Geomet or advanced zinc flake systems.
What is the difference between zinc flake coating and zinc electroplating?
Think all zinc finishes offer the same protection? I thought so, until one customer’s parts started rusting after just 48 hours in the field.
Zinc flake coatings offer better corrosion resistance and are safer to apply than electroplating, which involves acids and can cause hydrogen embrittlement.
Performance, Safety, and Waste—Key Coating Differences
Zinc electroplating applies a thin zinc layer using electric current in acidic or alkaline baths. It’s cost-effective but comes with downsides: acid fumes, wastewater, and hydrogen absorption. That last one—hydrogen embrittlement—is dangerous for high-tensile parts like bolts and shafts. You need post-baking to reduce the risk of failure.
Zinc flake coatings use no electricity. Instead, zinc and aluminum flakes are suspended in a binder and sprayed or dipped onto parts, then baked. These systems are often Cr6+-free and meet RoHS/REACH.
They’re thicker—usually 5–25 microns—and last up to 1000 hours in salt spray tests. Plus, there’s no hydrogen risk and little liquid waste. Many European buyers now prefer zinc flake for automotive and construction fasteners.
| Feature | Zinc Electroplating | Zinc Flake Coating |
|---|---|---|
| Process | Electrolytic, wet bath | Spray or dip, dry system |
| Waste Output | Acid, metal-rich liquids | Minimal, solid waste |
| Hydrogen Embrittlement | High risk | No risk |
| Environmental Safety | Low, due to acids/Cr6+ | High, Cr-free options |
| Corrosion Resistance | 24–96 hrs salt spray | 500–1000 hrs salt spray |
What is the difference between Geomet and Dacromet coating?
I used to group Geomet and Dacromet together. But once a customer flagged one and approved the other, I dug deeper.
Geomet coatings are Cr-free or use trivalent chromium, while Dacromet uses hexavalent chromium, making Geomet more environmentally acceptable.
Why Geomet Wins in Green Compliance
Both Geomet and Dacromet are zinc-aluminum flake coatings. They perform similarly on corrosion. But their passivation chemistries differ.
Dacromet typically uses Cr6+ for passivation, which is banned or restricted in many regions. Geomet systems use trivalent chromium or are Cr-free, making them RoHS and REACH compliant.
Their curing temperatures are also slightly different. Geomet systems usually cure at 200–250 °C. Dacromet can go up to 300 °C. Lower cure temps reduce energy use and risk of thermal distortion.
Today, I recommend Geomet first for European clients. It reduces paperwork, avoids hazardous waste classification, and keeps the environmental audit simple.
What temperature is zinc flake coating?
Worried about overheating parts during coating? I ruined a batch of aluminum housings that way—lesson learned.
Zinc flake coatings typically cure at 180 °C to 250 °C, depending on layer thickness and coating formula.
Cure Right or Fail Fast
Curing is what turns the binder solid and locks in the corrosion protection. Most zinc flake coatings need 180–250 °C for 20–30 minutes. That might sound simple, but it’s critical to monitor actual part temperature—not just oven settings.
Heavier steel parts heat slowly. Thin stamped parts overheat easily. Too little heat and the binder doesn’t harden. Too much and the flakes lose alignment or the part warps. I’ve seen coatings that looked perfect peel off after a few weeks—all due to bad curing.
For my clients, I now insist on thermocouple testing during first runs. It saves time and avoids warranty claims later. Energy-wise, curing at 180–220 °C also costs less than traditional coatings that need 280 °C or more.
Conclusion
Zinc flake coatings are cleaner, safer, and greener than Dacromet or electroplated zinc. They meet today’s environmental and performance demands without the headaches of Cr6+ compliance or acid waste.
