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Questions about zinc electroplating specification Fe/Zn8

An ongoing discussion from 2001 through 2014 . . .

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


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

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 at 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

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


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 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 abbreviations mean? Is everybody plating without the spec on hand, and issuing certs based only on internet rumors? Bone jure :-)

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

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
  ^- Privately contact this inquirer -^

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

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