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Metal finishing Q&As since 1989


Non-electrolytic blackening/coloring of aluminum: Decoral process

Q. We have a customer who is looking for an inexpensive black finish on aluminum. Currently we are producing sulfuric anodize with black dye but the pricing structure doesn't fit their program. Engineering properties are not a great concern although corrosion resistance would be nice. If anyone has had any experience with a black "CHROMATE" of aluminum I would appreciate the help.

Tim Martin
plating shop - Springfield, Massachusetts

Disambiguation: Be aware that there is an Italian company by the name of Decoral that offers a powder coating process with a wood-grain pattern, which may lead to some confusion on searches.

For a discussion of wood-grain finish processes, we suggest that you start with Letter 31347,
or for a discussion of Decoral specifically, that you start with Letter 14543

A. Hi, Tim. In your area, such a process was long advertised by Lea Manufacturing Co., Everett, MA as Decoral ®. Other suppliers may have a similar process, but I don't know any other trade names. The colors I've seen looked somewhat pastel rather than highly saturated, so I can't be sure how saturated the black color is and whether you'd be happy with it (as you doubtless know, anodizing needs to be quite thick to get a good black color). Good luck.

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

A. We do black anodizing & chromate (clear & yellow). Sandoz aka Clariant, who manufactures most of the world's anodize dyes also sells dyes for chromate, but most of the ones I have tried, including black, did not work well. I have some experience w/ Decoral - I have seen it in gold, and if the Black is similar, yes, that is a cheaper process than anodize. Good luck.

David A. Kraft
- Long Island City, New York

Bulk process for colorizing aluminum

Q. I'm looking for a cheap, easy bulk process to colorize small aluminum (5056) fasteners. No thickness or corrosion resistance required: only color.

Myron C [last name deleted for privacy by Editor]
- Stanfield, North Carolina

A. Hi Myron. I'd suggest investigating the Decoral process. I haven't seen it advertised recently, but the Metal Finishing Guidebook says it's a trade name of JacksonLea [Conover, North Carolina]. Alternately, you could investigate bulk/basket anodizing. Good luck.

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

Need Decoral J3 Red

Q. Anyone familiar with "Decoral J3 Red", apparently it's a red paint that can be used on Aluminum.


Mark Plunkett
- Santa Ana, California

"The Surface
Treatment &
Finishing of
Aluminium and
Its Alloys"

by Wernick, Pinner
& Sheasby

on AbeBooks

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A. Hello Mark. Decoral was a trade name held at one time by Lea Manufacturing Co., Everett, Mass for a line of chromate or chromate-like conversion coatings for aluminum which offered various colors. I don't think I have their technical literature on the process anymore, but ads can be seen on the back cover of plating magazines from the 70s. I suspect that 'J3 Red' may be one of those colors.

Also this process, like virtually every other finishing process for aluminum, is covered in "The Surface Treatment of Aluminum and Its Alloys"

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

A. Decoral Process used to be marketed by:

A Unit of Jason Inc.
Conover NC

(They may have dropped this for environmental reasons)

Frank Chermilac
- Yonkers, New York

Need conductive finish that looks like anodizing

Q. I currently finish our 6 series Aluminum with a 4-minute Etch followed by a Clear Anodize. My problem is that from time to time I need a particular part to be conductive after finishing. But, I do not want to pay the extra $ to mask off areas. The conductivity allows us to drain a static charge away from our fixtures via a grounded rail, in this case. I have heard (quite some time ago) that the Decoral finish is conductive. I do not know any more about it or if it is truly conductive. I am looking for help to find a finish that looks like the Etch and Clear Anodize that I currently am applying, but it needs to be conductive. I have sampled a 4 Minute Etch with a Clear Chromate, but surface marks are still readily visible. Any information is appreciated.

Joe Rose
PCB Test Fixtures - Maple Grove, Minnesota, U.S.A.

A. I have seen components that are used in plasma chambers for IC fab that are partially anodized and partially electroless nickel plated and the appearance match is so close you can't tell which areas are which. But if the operation is so cost-sensitive that masking must be ruled out, electroless nickel plating the whole unit may be cost prohibitive as well. I would suggest spending some more time trying to fine tune the clear chromate process.

For a long time I had assumed that Decoral was a chromate-based process, and conductive ... but the entry in "The Surface Treatment of Aluminum and Its Alloys" has disabused me of that :-)

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

RFQ. I have been trying to locate a source in the US who does the Decoral process. If you or anyone else has any information on shops offering this method of coloring, please let me know. I would greatly appreciate any assistance.

We are looking for a non-electrolytic coloring process for aluminum. We are looking for larger volume producers, either offering the DECORAL or another color process to achieve the look of anodized aluminum. Our aluminum is fine flake scrap.

Demir Hamami
- Maryland, USA
February 6, 2012

Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)

Decoral Metal Finish - Cold Chemical Oxidation of Aluminum

September 5, 2013

Q. It has been quite a challenge to find capable finishers or even industry experts who are familiar with the Decoral Metal Finish. We have used this finish in the past to blacken an assembled steel and aluminum component. It is a small metal fastener and it should be build processed. Currently anodize will not work on aluminum and steel assemblies. This Decoral has, but, we no longer have access to this finishing source.

According to a posting, this was a description of the finish:

"... cold chemical oxidation of aluminum, a process (known as Decoral) which produces a 1 to 2 µm thick transparent aluminium oxide film that can be coloured and works in slow rotating polypropylene barrels."

I have a few questions:
1) Why is this finish able to work on aluminum and steel assemblies (and why anodize won't)
2) Is there another commercially available alternative to Decoral that might be more popular and readily available.
3) Is there a ISO, MIL or other standard that encompasses this finish?
4) Who can process the actual Decoral Finish

Steve Sherman
buyer - New City, New York

Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)

A. Steve,
There is a metal finishing company in Waterbury, CT that offers Decoral on aluminum. Decoral is an anodizing alternative. I don't know of any MIL specification for Decoral.

blake kneedler
Blake Kneedler
Feather Hollow Eng. - Stockton, California
September 6, 2013

Alternate to Chromate finish and also provide Conductive surface

August 20, 2014

Q. Dear Ted and readers,

Thanks for being great help on so many occasions.

Require one more.

We extensively use Al6063-T5 & 6061-T6 with Dyed and Clear anodizing and it provides adequate non-conductive surface to our enclosure.

But we just realized that when keeping non-conductive enclosure affects the ESD test. Our main concern with ESD "Zapper" test, when Static charge hits the non-conductive surface they don't get discharge outside but due to nature of non-conductive surface they (Static charge) bounds within enclosure. This built-up static charge within enclosure are dangerous for very costly electronic components.

To avoid above situation, and to make enclosure surface conductive we have moved to Chromate finish from Anodizing. But Chromate finish luster is too "flaky" and biggest issue is "Coloured Chromate finish". We want our components to be Blue in colour.

1. Is there any alternate process to Chromate finish that can provide a CONDUCTIVE surface?
2. Is it possible to get dyed (Blue - PMS661C) Chromate finish?


Mihir Rawal
Component Engineer - Sydney, Australia

Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)

A. Hi Mihar. Traditional hexavalent chromates can be dyed, although it may be trickier with the new trivalent chromates. If you look at the ground screw on virtually any electrical box, you'll see that it is green -- this is zinc plated and chromate conversion coated rather than aluminum, but it should be the same idea. There was a time a few years back when America was slowing moving toward metric fasteners and some manufacturers were dyeing the metric sizes of their fasteners "metric blue". I don't think it's still trending, but if you google "metric blue fasteners" you will see lots of aluminum fasteners in that color (I don't know if they are anodized or chromated though).


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

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