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Dear Reader :

I am manufacturing phosphating chemicals (I started this as a hobby). I use phosphoric acid with zinc oxide and little nickel nitrate with sodium nitrate. This in a hot bath does not work. Can anyone guide me?


Harish Chitkara
- Chennai, India


Try sodium nitrite as an accelerator rather than sodium nitrate.

Ron Zeeman
Continuous Colour Coat - Brampton, ON, CAN


Can anyone suggest material sources for Class 4 phosphating as per DOD-P-16232 [ed. note: replaced by MIL-DTL-16232 [link is to free spec at Defense Logistics Agency,]]?

Aryeh Asher
- Ashkelon, Israel


Can you put your specifications in detail? Based on your requirement we can suggest for the chemical or the process.

- calcutta, INDIA


Dr. Aryeh Asher,

You might give Ted a wrong impression that there are no suppliers in your country....-:)

sara michaeli
sara michaeli signature 
Sara Michaeli
chemical process supplier
Tel-Aviv, Israel


Country? I thought Israel was a city.

Ted Mooney, Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

 (only joshing, folks)


Which is the best phosphating method for powder coated product? hot or cold.

irrigation systems - Jalgaon, M.S. INDIA


The best is usually the most difficult and most expensive, K.L. Zinc phosphate with a final chrome rinse is probably the 'best'.

Ted Mooney, Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey


I want to know the right pretreatment & powder coating process for metal irrigation water filters AS these filters will be always in contact with water & soil may have some contact with fertilisers ( specially in case of fertiliser tanks ) & of course always in open sunlight & mounted in the farm itself for paint durability & resistance to corrosion ,protection against weathering effect ?

I have already done experiments of existing seven tank pretreatments ? & various ( epoxy & pure polyester & hybrids )

if someone know specific way of coating of water filters & fertiliser tanks pl. tell me.

irrigation systems - Jalgaon, MS, India


We buy some spherical plain bearings from market & dealers give different brands according to availability. Japanese makes looks deep black colour, local makes are light grey. Catalogues say only phosphated. What is better? Black oxide also acceptable? Please clarify.


S M Sundaram
- Tamilnadu, India


Hi, go for manganese phosphate it blackish in colour and secondly it is recommended for the parts where some lubrication is required eg: bearings, pinnion etc. Grey finish is of zinc phosphate and zinc phosphate looks grey in colour.

Qutubuddin Saify
- U.A.E.


Dear Mr Saify,

Thanks for the reply. Would you suggest the cycle time for Mn Phosphating, because it is eating the material, or should we have to keep stock considering erosion. Pl advise for bearing steel material SAE52100, High Carbon High Chromium steel erosion pattern


- Chennai, Tamilnadu, India


Mn phos time should be 10 mins. The imported bearings are not Mn Phos, they get the dark tone on account of different heat treatment process.

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind supporting advertiser
Bangalore, Karnataka, India

saify logo


Dear Mr. Sundaram,

Keep the bath pointage around 30 35 ml, control iron to minimum and immerse the component when temp is 95 C and above for 10 min.

Prabhakar Gupta
- Kanpur, U.P., India

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