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Q&A's on MIL-P-23377 primer



A discussion started in 2006 and continuing through 2017 . . .

Is Mil-P-23377 suitable for Inconel?

(2006)

Q. I am reviewing an older drawing (2001) that calls for a coated area per MIL-P-23377. I read through the MIL spec & could not find any references to the type of material that this epoxy primer can be applied to, except aluminum. The problem is that my part is made of Inconel 718. Can this primer be used on Inconel 718? Is there another MIL spec that has a similar epoxy primer that is used on Inconel 718?

Thank You!

Denny Falls
engineering - Woodland Park, Colorado, USA


simultaneous (2006)

A. Denny,

MIL-P-23377 should be able to be applied successfully to Inconel. It has more to do with the preparation of the surface to produce a key for the paint rather than the suitability of the paint.

We currently apply MIL-P-23377 to various materials including stainless steel, titanium, nickel, aluminium (usually anodised or Alodined), alloy steels of various types and even to various composite and plastic materials.

What you need to do is probably to either mechanically work the surface such as alumina blast, bead blast or similar, or to chemically etch the surface, one of the nickel etches will probably do the job for you.

As always, when developing a process, run some test pieces first and optimise your conditions, ensuring you get good adhesion before you start applying it to production parts.

Brian Terry
Aerospace - Yeovil, Somerset, UK


(2006)

A. 1) Yes, and 2) Maybe yes, depending on use, if authorized.

MIL-PRF-23377J-A1 PRIMER COATINGS: EPOXY, HIGH-SOLIDS, Paragraph 6.1:
"...These primer coatings are formulated for the unique performance requirements of military aircraft. These requirements include adhesion to a wide variety of metals and composites..."

Paragraph 6.1.1 Compatibility:
"For some applications, and only when authorized by the procuring activity, MIL-PRF-85582, Primer Coatings: Epoxy, Waterborne, may be substituted for MIL-PRF-23377..."

But MIL-PRF-85582 is another primer used mostly for aluminum, with the limitation (Para. 6.1):
"However, primer coatings containing water, such as these coatings, should not be used on iron or bare carbon steel, nor for the wet installation of fasteners or faying surfaces."

Inconel 718 is mostly Ni-Cr, so no flash rusting problem but maybe limited adhesion. And, no substitution if MIL-PRF-23377 is required for wet installation of slip fits or press fits, etc; see MIL-STD-7179 for more information.

Note Paragraph 3.11f:
"Apply over pretreated metal ..." -- the only referenced pretreatment suitable for non-aluminum metals and FRP is a wash primer in accordance with MIL-C-8514.

Ken Vlach
- Goleta, California
contributor of the year

Finishing.com honored Ken for his countless carefully
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What is standard Mil-P-23377-5D?

(2007)

Q. Do you know of a company that carries a "5D" I cannot find that reference anywhere.
Thanks
JR

Jessie Roberts
buyer - AFB, California, USA


simultaneous (2007)

A. Jessie,

I can't say I know where the 5D comes from but my best guess is either in an earlier publication of MIL-PRF-23377 there was a kit designation of 5D (the Assist quicksearch goes back as far as revision F and it doesn't appear in there), or that there has been a misinterpretation of the kit designations and someone has made up their own (possibly 5dm3, or 5 litres).

For the rest of you out there, have you noticed the deliberate mistake in the kit designation table? Since when has 4 pints, 4 quarts and 4 gallons shrunk so much?!

Brian Terry
Aerospace - Yeovil, Somerset, UK


(2007)

A. No reference to '5D' in MIL-P-23377F (1989) thru MIL-PRF-23377J(A2) (2007) nor QPL-23377-16 thru -19.
Perhaps a manufacturing date code for 2005 Dec.
Where do you see this 5D?

Ken Vlach
- Goleta, California



Can MIL-PRF-85582 replace MIL-PRF-23377?

January 6, 2009

Q. Can 85582 be used in the place of 23377? My understanding is the 85582 is a waterborne version of the 23377. Our company engineer believes that only 23377 is acceptable however the Mil-PRF-23377 [link is to free spec at Defense Logistics Agency, dla.mil] J, amendment 2, section 6.1.1, says that
"For some applications, and only when authorized by the procuring activity, MIL-PRF-85582, Primer Coatings: Epoxy, Waterborne, may be substituted for MIL-PRF-23377".

Mil PRF85582 [link by ed. to spec at TechStreet]D, section 6.1, states
"These coatings are compatible with polyurethane and epoxy topcoats (see 6.1.1) and may be used as alternatives to MIL-PRF-23377 for many applications.".

Please let me know your thoughts.

Jeff Hendrix
Manager - Nevada, Missouri, USA


January 12, 2009

A. The two primers are similar, the 85582 being water reducible. They are usually considered interchangeable, but make sure that you have permission from the design authority before you try to make any changes.

Brian Terry
Aerospace - Yeovil, Somerset, UK


Unwanted glossy surface of MIL-PRF-23377 epoxy primer

May 15, 2009

Q. I have been using MIL-PRF-23377 epoxy primer.

Normally, its coating has non-gloss (flat) surface, but, sometimes semi-gloss surface (value: 15 ~ 30 at 60 °) is obtained, even in the same batch material.

I am wondering if there is any factor in operation to affect material gloss (e.g., mixing ratio, addition of thinner, curing condition, or coating thickness, etc.)

Thanks in advance.

DC Park
Painter - Korea

May 20, 2009

A. DC-
All of the above.

Sheldon Taylor
   supply chain electronics
Wake Forest, North Carolina




June 9, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Applying MIL-PRF-23377 Type 2 (Green) primer to a flat finish? To start, I've been working in the aerospace industry for around six years, namely in the painting of commercial and military parts for whomever pays money to my company.

I've painted with all manner of primers and topcoats (e.g. BMS 10-11 type I and II, BMS 10-83, MIL-PRF-85585, -85285 etc.), but I haven't found a good way to apply this one paint.

It's a low-IR reflective primer that I mostly see for parts used on a certain helicopter company's products; the beast of a paint applied to the MIL-PRF-23377 Type II spec.

The problem is, our customers like the finish to look flat, but applying the primer to the paint manufacturer's instruction seems to make it come out mottled and glossy. I know that this question is pretty obscure, and I don't expect an answer, but I saw this forum while researching the subject, and I figured, "hey, why not?"

Chris Stapleton
Aerospace Industry Painter - USA


June 11, 2014

A. Hi Chris,

MIL-PRF-23377 paints are usually pretty good at doing exactly what it says on the tin when used in accordance with the manufacturers technical data sheet (TDS). Does your customer have some sort of strange mixing or application requirement that doesn't meet the manufacturers TDS?

As stated in the previous posting many things can affect gloss levels, but I have found some paints are very sensitive to the mix ratio and the level of thinning, so make sure that is strictly controlled and that the viscosity of the paint is right before you spray it.

Brian Terry
Aerospace - Yeovil, Somerset, UK


June 27, 2014

A. We use the Mil-PRF-23377 from Akzo and it is most definitely glossy when used as instructed by the TDS.

When we switched from the MIl-P-23377 product we thought we had missed something as that was as flat as a pancake!

As Brian mentioned, stick with the manufacturers instructions and you won't go far wrong.

Adrian Yeo
Aerospace Surface Treatments - Chelmsford, Essex, UK



Class C1 vs. C2

November 10, 2014

Q. What are the advantages/disadvantages of using class C1 vs C2?

Darryll Fletcher
- San Luis Obispo, California, USA



MIL-DTL-53030

November 7, 2016

Q. My company has an order to make a aluminum part from 2024 plate. On the drawing it states to apply epoxy primer MIL-P-23377, and then apply a Green 383 top coat.
On the order there is a reference to MIL-DTL-53030.
Searching on line I see that MIL-DTL-53030 is an epoxy primer. That spec refers to a QPL, which shows several products.

My question is how does the MIL-P and the MIL-DTL specs co-exist? And in this case does the MIL-DTL call out supersede the MIL-P spec noted on the drawing?

David Murr
- St. Charles Missouri USA
  ^- Privately contact this inquirer -^


November 2016

A. Hi David. It looks like MIL-DTL-53030 coatings are chromate-free, and that MIL-P-23377 was superceded by MIL-PRF-23377 more than twenty years ago. Although MIL-PRF-23377 lists type "N" coatings which are chromate-free, it also says they can only be used in special circumstances. So my guess is that your customer is telling you that they want chromate-free coatings these days.

Although that is what I would assume is going on, you know the consequences of assumptions, and should now verify with your customer exactly what they've ordered and that you have the permission and authority to ignore the requirement for a MIL-P-23377 coating. Please note that per MIL-PRF-53030 section 6.1 "Intended Use", it is quite clear that this water-based chromate-free coating cannot be used on aircraft.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



February 23, 2017

Q. Is the M23377-1-C-2 the same material as the MIL-PRF-23377-1-C-2. Before I assume that the M2377-1-C-2 was superseded by the MIL-PRF-23377-1-C-2, I thought I'd better ask.

Thanks.

Mark Anderson
- Littleton, Colorado USA


February 28, 2017

A. Mark,
At some point a few years ago, the designations of most of the military standards got changed a little. The numbers all stayed the same, though.

If you look up this spec at http://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=16259
you can see that it used to be MIL-P-23377 and is now MIL-PRF-23377.

It looks like M23377-1-C2 is the part identifying number for parts done with MIL-PRF-23377 Type I Class C2 designated coatings. (Paragraph 1.3 of the spec.)

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois


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