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Questions about zinc electroplating specification Fe/Zn8

An ongoing discussion from 2001 through 2015 . . .

Fe/Zn 8 clarification of required thickness


Q. When ASTM B633 [link by ed. 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

To minimize searching and thrashing, and to provide multiple points of view, combined formerly separate threads into the single dialog you are now viewing. Please forgive any resultant repetition.


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 the case.


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

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 [link by ed. to spec at TechStreet]] demands.

John Martin
- Wales

June 1, 2012

A. That is part of ASTM F-1941

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 [link by ed. to spec at TechStreet] -- but who can say that there isn't another spec somewhere, perhaps from another country, which has a Fe/Zn 8 C5 paragraph? Even if we agree on what these letters mean in one spec, we can't be sure what is wanted without a spec number.

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

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, MI, 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 (totally 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.

metal finisher - Gurgaon, Haryana, India

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 admittedly 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. RET
Pine Beach, New Jersey

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. RET
Pine Beach, New Jersey

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

April 12, 2011

RFQ: 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

July 2, 2012

Q. What is HB in 'Ep-Fe/Zn[2]/HB CM2'?

Yan Biau Chow
- Singapore

July 5, 2012

A. Hi.

HB indicates a post treatment of Baking for Hydrogen removal.

SK Cheah
- Penang/Malaysia

April 16, 2013

Q. What about CM(iii)3?

- Seremban, NS, Malaysia

April 9, 2013

Q. What does EP-Fe/Zn-Ni8/CM2C mean? Could you help me to understand this specification?

Armando Diaz
- Metepec, Mexico

April 16, 2013

A. I'm really not understanding this thread, cousins. Doesn't the spec say what its own abbreviations mean? Are people plating without the spec on hand, issuing certs based on internet rumor?

Bone jure :-)

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

July 16, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. We have some steel fasteners in our older drawings with a description of "GRADE 5, 2C". Our internal part number corresponds to, for example, McMaster 90126A031. I assume that the 2C designation is meant to suggest the zinc-plated finish but I haven't been able to find a standard that it would be associated with. The only references I've found are ASTM A193 (appears to refer to a heat treat for SST) and BS1706, where it doesn't mean much without additional context. Our customer is now asking for clarification so I need to come up with an answer. Can anyone give me a hint? Thanks!

Mark Treadwell
engineer - Baltimore, Maryland

What is SEZn-CM finishing?

May 14, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi, I'd like to find out what is SEZn-CM finishing. This is stated in my customer drawing under surface treatment so I'm checking what finishing is this.

Best regards

Ivan Teo
- Singapore

May 27, 2014

A. Hi Ivan,
If this is on your customer drawing your best bet is to ask your customer what it means.

Never ceases to amaze me, how were you ever able to quote for the job if you didn't understand what it entailed?

Brian Terry
Aerospace - Yeovil, Somerset, UK

December 10, 2014

Q. Hi Team,

Anybody able to advise me whether DIN 50691 Fe/Zn8b is equal to ASTM B633-98?

Sugumaran s/o Doraisamy
- penang malaysia

A. Hi Sugumaran. I am not able to easily find a "DIN 50691" spec. and suspect a typo, and that you meant DIN 50961 [link by ed. to spec at TechStreet]. That spec and ASTM B633 [link by ed. to spec at TechStreet] are different specs and certainly not "equal" -- but it is probably possible for your plating to comply with both of them.


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

What is Ep-Fe/Zn8/C? Same as ISO 2081?

August 28, 2015

Q. I'm finding global specification callout comply with PFZn8-C. I'm not sure where this callout comes from. I guess it's the same with Fe/Zn8/CM2. Am I correct? Then can I use ISO callout ISO 2081 Fe/Zn8/C?

One more thing: Is there any expression which regulates trivalent passive chromate?
Sorry for many ugly questions ...

Seungsik Won
- Daejeon, Rep of Korea

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

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