Trivalent chromium color zinc passivator

Zn-237 is a trivalent chromium color passivation system used on the galvanized layer. The coating has high corrosion resistance and does not contain organic acids. Through a simple dipping process, the product can be uniformly bright, deep color yellow thick passivation film with strong chromium bonding force.

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Product Description

Trivalent chromium color zinc passivator

Trivalent chromium color zinc water Zn-237

Zn-237 is a trivalent chromium color passivation system used on the galvanized layer. The coating has high corrosion resistance and does not contain organic acids. Through a simple dipping process, the product can be uniformly bright, deep color yellow thick passivation film with strong chromium bonding force.


1.  Zn-237 A and Zn-237 C can get the same color as hexavalent chromium passivation.

2.  Does not contain hexavalent chromium.

3.  At room temperature, a uniform and bright passivation film is produced.

4.  The salt spray resistance of the passivation layer of Zn-237 is better than that of the hexavalent chromium passivation layer.

5.  Equipment and technology for hexavalent chromium passivation can be used.

6.  At room temperature, a yellowish colored thick protective layer is produced.



1.Zn-237 A can be used as a separate component, and the minimum salt spray test time is 150 hours.

2.Add Zn-237 C in the amount of 5-20 ml/liter , and the coating color can become darker.


Process flow:

Galvanizing → water washing → 0.5% nitric acid → water washing → Zn-237 → washing → drying

Operating conditions:


Ordinary color passivation

Deep color thick coating passivation

Zn-237 A



Zn-237 C









Soaking time

30-90 seconds

30-90 seconds

Rolling speed



Note: It is recommended to use Zn-237 B (liquid) in the passivation of deep color thick coatings . Zn-237 B plays an obvious role in barrel plating .

Control Method:

     Regularly analyze the addition of Zn-237 and dilute nitric acid, sodium bicarbonate or sodium carbonate to adjust the pH value.

     Replenish according to the passivated working surface area, after 100 dm² (10 ft²) work, add 30-35 ml Zn-237 A. Zn-237 depends on the carry-out loss.


Zn-237 content

1) Take 2 ml of Zn-237 plating solution into a 250 ml conical flask.

2) Add 50 ml of pure water.

3) Adjust the pH to about 10 (add 10-15 ml of 10% sodium hydroxide, the solution turns green).

4) Add 1.0-1.5 ml of hydrogen peroxide.

5) Boil the solution for 30-45 minutes until the liquid volume is reduced to about 1/3, and the excess hydrogen peroxide is evaporated.

6) Add 100 ml of pure water to dilute the cooling solution.

7) Acidified with concentrated hydrochloric acid (15ml), the color of the solution changed from yellow to orange. May heat up, then cool down.

8) Add 4-5 ml of 10% potassium iodide solution (dark red), then add starch solution.

9) Titrate with 0.1 equivalent sodium thiosulfate solution until the black color disappears.

Calculation method

Zn-237 (%)= titration reading×N×16.7


Operation note:

1.Tap water or pure water can be used to open the tank.

2.The passivation effect will be better if the air is used for gentle stirring or the plating parts are moved and stirred.

3.The drying cycle temperature does not exceed 120°C.

4.The workpiece that has fallen into the plating solution must be removed as soon as possible, otherwise the life of the plating solution will be affected.

5.The lining material of the plating tank should be polyvinyl chloride or rubber.

Manufacturer of high-quality electroplating additives    

Trivalent chromium color zinc passivator  Faq

1. Q: Do you make the products yourself? Are you a trader or a manufacturer?

     A: Yes, the products are produced by our company. Our company is a manufacturer focusing on the R&D and manufacturing of environmental protection electroplating additives. Our factory has 5000 square meters with an annual capacity of 15000 tons.

2. Q: Can your company send samples for trial?

     A: We can provide samples for trial.

3. Q: What is the quality of your products?

     A: Our company all products core raw materials is used by Germany BASF, American Dow Chemical and other international brand products. The production process is strictly in accordance with the ISO9001 quality management system, from the incoming inspection, product inspection, according to the strict inspection standard, ensure that every drop of products qualified. Product quality you can rest assured, like BYD, Huawei, Foxconn such enterprises are also using our products.

4. Q: How long is the shelf life of your products?

     A: The shelf life of our products is two years. If you do not use up the products within a short time after you buy them, we suggest you store them in a cool place, not in the sun or in a high temperature environment.

5. Q: Are your products environmentally safe?

     A: Our products have passed the SGS test and are recognized as "Green and Environment-friendly Promotion Products". Many auto parts and electronic products which use our products can pass the strict environmental protection test when they are exported to Europe and America. Therefore, we can be trusted in terms of environmental protection and safety.

6. Q: Can your company provide technical services?

     A: Yes, our company has a technical service team of more than 10 people. The technical engineers all have more than 20 years' experience in electroplating factory. They can provide customers with comprehensive technical of pre-sales and after sales.

7. Q: Is it possible to visit your company?

     A: Yes, of course. You are very welcome! We can meet you at Jieyang airport, If you can come to our city. Also you can visit our factory through live video.

8. Q: Can you customize products according to our needs?

     A: Yes, our company has research and development strength, the product formula derived from Europe and the United States laboratory, European and American engineers technical support, work together with domestic universities. Our company has a member of Guangdong province expert enterprise workstation, Shantou university science and technology correspondent workstation, Jieyang city environmental protection engineering research center for electroplating additive.Therefore, it can meet all kinds of customized requirements proposed by customers.

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