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A discussion started in 2004 but continuing through 2019


Q. We are currently on a refinery project in the South east and one of our scope is to supply and install cold supports. Our bolts and nuts are required to have a finish of bright zinc plated passivated to class 2d as per BS1706 spec. We have been offered a passivation class 2C. Due to lack of reliable literatures we would like to ask your opinion if the deviation from 2D to 2C are of tolerable property. Our latest lab test report in Singapore approves 25 micron plating thickness for class 2d. any info on 2c?

Will appreciate very much,


Ver Chavez
materials / logistics - Kuala Belait, Brunei


RFQ: I have 60 pieces of outdoor equipment rack, sizes: 1000 w x 900 d x 2000 h. The cabinet is made of 3 mm mild steel sheet with compliance to EN10025 and BS729.

The coating is electroplated zinc passivated to BS1706 class B Zn 3 and an anti-graffiti two-pack polyurethane finish.

The working location is south China.

Best regards,

Electronics - Hong Kong, China
^- Sorry, this RFQ is outdated
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Q. Dear ladies/sirs,

I need badly to know the standard of BS1706-FE-ZN5.

Who can tell me?

Thank you very much!

Best regards,

Will Wang
Metal Industry - Shanghai, China

May 2013

A. Hi Will. This is a specification for a minimum thickness of 5 microns of zinc on a ferrous substrate. My understanding from previous postings on this site is that BS-1706 was superseded by BS EN 12329 [affil. link to spec at Techstreet], itself later superseded by BS EN ISO 2081:2008. You should probably get a copy of that spec and ask your customer to change the spec to the current one. Good luck.

Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

2004 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Could you explain to me about Fe/Zn 8c2C per ISO 2081 [affil. link to spec at Techstreet] and ISO4520 amx THK 20 microns.


Tawatchai Sujitranuruk
plating engineer - Bangkok, Thailand


thumbs up sign Thank you for your several recent helpful responses to other people's questions, Tawatchai. Do you wish to order these two ISO specs, but need to know from where?

Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha


Q. Thank you Mr. Mooney for your call back. This specs above my customer requires. Could you introduce me for the name of electro plating standard hand book? Because I want to know the matter inside such as: ISO_ _ _ for Cr plating maker must do Ni plate how many micron, Cr plate how many micron, how much time for salt spray test, etc.

Best regard,

Tawatchai Sujitranuruk
- Thailand

A. Hi again. I think I understand. The way this works is there are a number of standards writing bodies (ISO is one of them), and there are individual specifications for different types of plating (for example, ISO 2081:2088 is a spec for zinc plating). Then that spec may offer options such as different thicknesses of zinc plating and different types/colors of chromate conversion coatings. If you look at a copy of ISO 2081:2008 you will understand the idea. Good luck.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

sidebar2 2004

I know that advertising is not normally permitted here but in the spirit of international cooperation this may get through Solutions and Subscriptions Book Promotion & Service Co. Ltd. Contact: Mr. Lee Pit Teong 2220/31 Ramkhamhaeng Soi 36/1 Haumark, Bangkok 10240 THAILAND E-mail:

Ranjan [last name deleted for privacy by Editor]
- Mumbai, India

Ed. note: Hi cousin Ranjan. Actually we encourage advertising just like magazines do! But like the magazine publishers, we find that it's usually better if commercial info & advertising is paid for and clearly identified as such.

Plus, this site can exist only for as long as advertisers support it, yet here we are spending our advertisers' money steering potential customers to your standards service instead of theirs? Some readers might think it a public service for to kill itself off that way :-)
... but hopefully not all readers do.

October 5, 2010

Q. In the UK "BS EN ISO 2081" is used for specifying "electroplated coatings of zinc with supplementary treatments on iron or steel". However in this standard there is no mention of thick-film / full or thin-film passivation. There is also no mention of trivalent or hexavalent versions of the chromate conversion coatings.

Does anyone know how to specify these properties? Is there another standard that I am not aware of?

Tim Douglas
product designer - London, United Kingdom

October 2010

A. Hi, Tim. Half of your question will be easy to answer. You simply add the requirement of RoHS-compliant trivalent chromate to your referenced spec. "... in accordance with BS EN ISO 2081 except that chromate conversion coating must be RoHS-compliant trivalent coating."

The other half of your question, thick-film vs. thin-film, is more difficult because as far as I know there is no standard covering that yet. Modern trivalent chromates are still highly proprietary. You can specify a brand and process name, but that can severely limit the number of plating shops available to you.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

February 13, 2019

Q. Having both standards for same component to be plated, one is BS EN ISO 2081 Fe/Zn25/D & another is BS EN ISO 12329;2000 Fe/Zn25/D. are both the same or any differentiation in it?

rohit patil

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