We deal with Manufacturing of Automobile and Industrial Speciality products

Our products come out from Coimbatore, which is the manchester of South India, having all adequate and modern machinery to process the raw materials and ensuring the premium quality of finished products to customers. We have well equipped testing laboratory for quality control of products.


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“ZINPHOPHOS – CZP” is designed to provide zinc phosphate coating with thickness of 200–300 mg/sq.ft within 30 - 35minutes on iron & mild steel components by simple immersion method at ambient temperature. This coating serves as good base for paints and any type of organic coating

Bath Make up : The tank should be free from grease, oil, rust, scale, etc, and should be coated with FRP or PVC or non – reactive material to bath solution.


For optimum results and maximum life of solution regular testing should be done using the analytical procedure outlined under the heading “control ”.


During the phosphate process, ferrous ions build up in the solution. If the ferrous ion contents exceeds 0.4%, it affects the corrosion resistance and performance of coating. So, Ferrous ion should be checked and maintained below 0.4% by either discarding the solution completely or partially. The method of analyzing the ferrous ion content is given under the heading "control".


During the operation of phosphate process, sludge a natural by – product of the Chemical reaction is formed slowly at the bottom of the tank. The bath solution should not be stirred up while jobs are being processed, otherwise dusty coatings may result. The sludge should be removed from the bath preferably twice or thrice a month


The starch Iodide paper is used to test the accelerator concentration in the bath. Dip strip of SI paper in bath, after some seconds colour will appear, it indicates the concentration of accelerator in the bath.

Insufficient Accelerator - Remains white.

Optimum Accelerator - Turns pala purple

Correct Accelerator - Turns light blue.

Excessive Accelerator - Turns dark blue.

Excessive Accelerator - Turns dark blue.

To get the best result, add sufficient amount of accelerator, Excess addition will cause in due wastage and excess sludge formation

Insufficient quantity came in accumulation of iron salt and affect the coatings.



The total Acid (Pointage) of the bath solution should be maintained between 28 to 32 points.

To find the total acid pointage (Total acidity). Stir the bath and take 10CC of bath solution into conical flask. Add 5 to 6 drops of PHENOLPHTHALEIN indicator. Titrate against 0.IN NoaH solution,

will give 28 to 32 points reading which represents the total pointage (Total Acidity) of the bath solution. To raise the pointage, add 2.5 litres of “ZINPHOPHOS – CZP” per 1000litres of bath for one pointage increase. It is recommended to maintain the pointage by regular additions of the chemical periodically.

To find free acidity take 10Ml bath solution and add 3 to 5 drops of BROMOCRESOL GREEN indicator and titrate against 0.1N NaoH solution. The result is yellow to light green colour change. The pointage should be 2 to 3


Pipette out 10ml of bath solution into a conical flask, add (3~5ml) of sulphuric acid (50% Concentration) to it. Titrate against 0.1N potassium permanganate solution, the result is colourless solution changes to permanent pink colour.

No of ml 0.1N of KMno4 required * 0.056 = % of Ferrous ion.


The components to be phosphated should be free from oil, grease, dirt, rust, scale etc,.

Generally, the following process cycle is adopted for M.S. components


Normally Alkaline and Emulsion degreasers are used for degreasing process. It is easy, economic and operator friendly process


Rinse the job in a clean cold continuously overflowing water for 60 seconds. After emulsion degreasing maintain a pH between 6 – 7. If the pH is less than 6, remove the water replenish it with fresh water


An acid pickle should be employed where rust, scale and oxides are present. For iron castings, high carbon steel, and for quality phosphating, phosphoric acid base compositions are recommended for pickling process.


After Pickling, rinse the job in a clean cold continuously overflowing water for 60 seconds. After emulsion degreasing maintain a pH between 6 – 7. If the pH is less than 6, remove the water replenish it with fresh water

V. Phospating:

As described in the heading “PROCESS”.


After Phospating, rinse the job in a clean cold continuously overflowing water for 60 seconds. After emulsion degreasing maintain a pH between 6 – 7.
If the pH is less than 6, remove the water replenish it with fresh water


After phospating, dip the jobs for 1 ~ 2 minutes into “PASSIVAT–CZP” solution to seal the phosphate coating and act as a sealant for better corrosion resistance and better adhesion of paints.


1. Degreasing : 30 - 35 minutes.

2. Rinsing : 30 - 35 minutes.

3. Pickling : 30 - 35 minutes.

4. Rinsing : 30 - 35 minutes.

5. Riance Modifier : 30 - 35 minutes.

6. Phosphate : 30 - 35 minutes.

7. Passicavation : 30 - 35 minutes.

8. Dry : 30 - 35 minutes.

9. Powder coating or painting or any organic coatings.


"ZINPHOPHOS - CZP" is strong acidic and oxidizing in nature. Normal safety precautions such as rubber gloves and aprons as well as safety glasses should be worn when handling these chemicals. In case of contact with skin, wash with plenty of cold water and for eyes, flush with plenty of pure cold water and seek medical attention immediately

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About Us

Priyadarishini Chemicals is engaged in Manufacturing of Automobile and Industrial Speciality products from INDIA since 1997 with the aim of providing premium quality products to its valuable customers.

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For any enquiries on our products,

Wired: +91.422 2567040, 2567114. Wireless: +91.8508888111.
e-Mail : info@prichemgroups.com

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