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topic 35197

Questions about zinc electroplating specification Fe/Zn8

A discussion started in 2001 but continuing through 2019

Fe/Zn 8 clarification of required thickness


Q. When ASTM B633 [affil. link to spec at Techstreet] specifies SC2 (Fe/Zn8) does this mean a minimum or an exact? Can the supplier send us material with a range of 8-12 microns with the 9-12 microns having a deposit build up which interferes with the functionality of our part?

Janice Tessier
- Sealy, Texas


A. To the best of my knowledge, the thickness is the minimum. It would be very difficult to obtain a certain thickness exactly, for example 8 microns. We need to have a range on the thickness.

You could specify also a maximum thickness, and work with your supplier to see if it is possible to work on this range.

I hope this helps.

Enrique Segovia
- Monterrey, Mexico


A. Hello Janice,

Is the product that you are having a problem with a fastener? The spec. Fe/Zn 8 calls out a minimum specification (0.00031") for zinc on steel, I believe. However, a standard 2A/2B thread fit only has an allowance for finishing of 0.00025". If the plater is trying to meet the intent of the specification which you have called out, and the fastener is relatively long, it is very possible that there will be enough zinc on the starter thread to cause a thread interference. The same issue can occur on a stamping with a threaded hole.

Hope that this helps.

Best regards,

Brian A. Calver, CEF
- Grimsby, Ontario, Canada

March 31, 2010

A. You could specify the maximum thickness allowed for Fe/Zn 12 classification.

Thiagaraj Maruthi
Engineer in conveyor manufacturing - Kluang, Johor, Malaysia

Zn6 with passivate bi-chromatic


Q. We have had a request regarding ZN 6 Passivate Blue. What does the 6 mean?
Why Blue over gold or clear?

Also what is passivate bi-chromatic?

Are there any links to good websites describing the finishes and passivation process?

David Lovegrove
Product Design - Christchurch, New Zealand


A. David,

ZN6 passivate blue is zinc plating with blue passivation using hexavalent chrome.
Now since hexavalent chrome is being phased out,blue passivation with trivalent chrome process is commercially available which is superior to dichronate type hexavalent chromium process. The neutral salt spay life before white rust as well as the finish is better than the latter.

However, yellow iridescent passivation (what you are referring to as "gold")has better corrosion resistance than blue passivation ("clear.")

- Mumbai, India


A. Zn6 is 6 microns of zinc.

John Martin
- Wales


A. I have read your question and read the answers. I must admit both could be correct. I think you need to go back to your customer and ask him exactly what he wants. It is a problem in the plating game when a customer gives a "spec" like that (internal spec) that is not clearly understood by the plater.

gary joseph
Gary Joseph
Johannesburg, South Africa

To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)


Q. We are quoting a electroplate spec and want to better understand the "breakdown" of the spec. Ep-Fe/Zn8/CM2.

Kim Hewitt
Metal Stamper - Fraser Michigan

May 11, 2009

A. Ep : electroplate
Fe : substrate to be plated
Zn : kind of plating
8 : thickness (8 mic)
CM1 : blue chromate
CM2 : yellow chromate

Joko P. Yuniartanto
- Bekasi, West Java, Indonesia

A. Hi Kim. Hopefully Joko's reply answered your question satisfactorily. Still I would warn that several different zinc plating specs might include a type Fe/Zn8/CM2, while including additional requirements about testing, lot size, etc. So you probably should be careful to call it out as "ASTM spec. no xxxx type Fe/Zn8/CM2" or "ISO xxxx type Fe/Zn8/CM2" or "Nissan xxxx type Fe/Zn8/CM2" or whatever is the case.


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

What is Fe/Zn 5 c 2C F-010


Q. I have a customer drawing that states on the finishing field the follows:
ZINC PLATE Fe/Zn 5 c 2C F-010.
As far as I know this is a Zinc Plating over steel, 5 microns, chromate; however I don't know what the rest of the spec. means "2C F-010".
Could somebody help me with this?

Julio Espinoza
Plexus Electronic Assembly - El Paso, Texas


A. Can't you go back to your customer and ask what body issued the standard?

It has the look of a European standard but is not written in the manner which the relevant standard (EN 12329:2000) [BS EN 12329 [affil. link to spec at Techstreet]] demands.

John Martin
- Wales

June 1, 2012

A. That is part of ASTM F1941/F1941M [affil. link to spec at Techstreet]

FE/ZN = Zinc, 5 = .0002 Min thick, C = Yellow

Matt Kelly
- Wheeling, Illinois, USA

March 25, 2008

Q. According to my customer's drawing, it requires surface treatment: Fe/Zn 8 C5. I don't know what "Fe/Zn 8 C5" means. Please inform me if somebody knows, thanks.

Claire Hsieh
exporter of fasteners - Taipei, Taiwan

March 26, 2008

Hi, Claire. It's probably ASTM B633 [affil. link to spec at Techstreet] -- but who can say that there isn't another spec somewhere, perhaps from a given company, which has a Fe/Zn 8 C5 paragraph? Even if we agree on what these letters mean in one spec, you can't be sure what is wanted without an actual spec number.

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

April 17, 2008

A. Fe/zn 8 c5 :
means zinc coated iron with 8 micron thickness


Spec: Ep-Fe/Zn 8B free from Hexavalent Chromium (White)

May 20, 2009

Q. I have a print with this plate spec, and just want to make sure that I understand it correctly. As far as I know it is a .00031 min plate thickness, ROHS.

Is there a specific salt spray for this?

Any words of advise would be appreciated.

Amy Kolodziej
plate shop internal - Wyandott, Michigan, USA

May 29, 2009

A. Hi Amy,
Yes the thickness is 0.00031 inch. This spec means white rust should not appear in 48H, and red rust in 96H more (total 144H).

Joko Prasetyo Yuniartanto
- Bekasi, West Java, Indonesia

March 23, 2012

A. We follow the detail FEZN8B.
Components require salt spray life up to 240 hours as per drawing of Honda components.

A.S. Kalsi
metal finisher - Gurgaon, Haryana, India

thumbs up sign Joko and A.S.'s contradictory answers should demonstrate that it would be foolish to proceed without knowing what spec number was to be followed for "Ep-Fe/Zn 8B" and to quote, let alone plate, let alone certify, without the spec in hand :-)


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

What is EP-FE/ZN10 BK Plating?

July 27, 2009

Q. Hello,

We have a customer from Japan that requires plating I have never heard. They are specifying Ep-Fe/Zn10 bk. I have contacted our plating shop and they have never heard of this type. It seems it is Zinc plating 10 microns thick, but what does the bk stand for? Please help.

Russ Kinyon
OEM supplier - Hutto, Texas

July 30, 2009

A. My bet is that "BK" means black chromate, but a guess is no substitute for an authoritative answer :-)

I think you need to find a copy of this specification. It's probably a JS standard. Good luck.

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

October 13, 2009

Q. What is the meaning in the electrolytic coating spec "Fe/Zn8/F1" Pc:black passivation Cr+3 Fe/Zn8/F1 - FTR 00025 for an electrolytic coating of zinc on steel, with a minimal thickness of 8µ, is having a black layer of Chrome III passivation?

Ozgur Usluer
plating shop employee - Izmir, Turkiye

October 14, 2009

Hi, Ozgur. 'Black passivation Cr+3' must surely mean trivalent chromate conversion coloring in the color black. "FTR 00025" doesn't mean anything to me -- sorry. You can't proceed without a copy of the specification, so please ask the buyer to supply a copy of it or tell you where to get it.

Good luck.


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

What type of plating is Ep-Fe/Zn 5/HB, CM2 C?

April 12, 2011

Q. We are quoting a job that has this requirement.

Renee Rider
Quality Manager - Columbus, Ohio, USA

What does "TLP" mean in spec Fe/Zn8/TLP?

June 24, 2012

Q. What is the TLP meaning in the electroplate spec Fe/Zn8/TLP

- Johor Bahru, Johor, Malaysia

June 26, 2012

A. Hi. Google tells me that TLP stands for 'thick layer passivated'.

SK Cheah
- Penang, Malaysia

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Ed. note:
Please see letter 26629 for another long list of similar sounding Q&A's about plating specs.

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