Chrome on aluminum; The pros & cons

[Bright-Lee]

Ok, first a little about how I became the “BUFFERMAN”.
In 1982, I applied for a job listed in the paper (Shop helper no exp. needed).
I had no idea I was about to become a chrome plating tech. I quick-Lee
learned about a variety of metal coating/treatments such as: black oxide, electroless nickel, electro-polishing & plating, and of course, (mechanical) buffing/polishing.
It was here that I learned the basics of metal polishing. In order for chrome to look good
a part must be polished prior to plating. However, the degree of luster is not as important as looking for and removing pits, while keeping shapes and tolerance.

After a few years I worked my way into an anodizing company as manager of the polishing dept. Here I perfected my skills on aluminum. The owner was always demanding higher levels of quality/luster.


For the past 8 years I have been owner/operator of Bright-Lee Polished Metals.
It is here that I have mastered the art of metal finishing.

Now that I have told my life story, I will try to explain the pros & cons of chrome on aluminum.

THE PRO’S
Very high luster
Does not dull or fade
Easy to clean

THE CON’S
High cost
Long turn-around (if having something done you already own)
Short life (does flake, peel and chip)
No touch-ups (re-works only) which leads us back to high cost.

TO EXPLAIN
Chrome, as most people know it (like on bumpers), is really just a thin layer of copper then a slightly thicker layer of nickel then a flash (super thin) layer of chrome.
It is all done with electricity in liquids/chemicals not much warmer than your morning coffee. (About 140 deg. F.)

Aluminum is a relatively soft metal and is somewhat porous. If you happen to read about the gas cap with the chrome peeling due to vapors trapped underneath (another topic here in the Forum), that is a typical problem. However when I saw the back of the cap, it looked as if there was possibly machining oil still present when it was plated, another common problem.
More problems, in many cases, are due to the shape of the part to be plated.
Imagine chrome is like metal dust. If you were to sprinkle this metal dust over a magnet shaped like the letter “V”, the dust will cling to one side or the other and never make it to the bottom. This problem is overcome by making what is called an anode.
Anodes are lead bars connected to the positive electric pole and strategically placed to activate the plating process. Anodes aren’t always used where they should be because of the lengthy process required to set them up. This results in poor coverage in cracks and corners.

Since aluminum expands and contracts much more than chrome, under even mild temperature changes, the results are stress cracks that allow the weather to enter and do further damage. This is the primary reason for even the best of work that’s gone bad.

In regards to chrome over steel, well that’s a whole separate set of pros & cons.

I hope this wasn’t too boring and maybe even answered a question or two.

To everyone who has trusted me to polish his or her skid plate, I thank you very much! And Jason, thank you—this site rocks!

James
www.brightlee.com

[Bright-Lee]

Ok, first a little about how I became the “BUFFERMAN”.
In 1982, I applied for a job listed in the paper (Shop helper no exp. needed).
I had no idea I was about to become a chrome plating tech. I quick-Lee
learned about a variety of metal coating/treatments such as: black oxide, electroless nickel, electro-polishing & plating, and of course, (mechanical) buffing/polishing.
It was here that I learned the basics of metal polishing. In order for chrome to look good
a part must be polished prior to plating. However, the degree of luster is not as important as looking for and removing pits, while keeping shapes and tolerance.

After a few years I worked my way into an anodizing company as manager of the polishing dept. Here I perfected my skills on aluminum. The owner was always demanding higher levels of quality/luster.


For the past 8 years I have been owner/operator of Bright-Lee Polished Metals.
It is here that I have mastered the art of metal finishing.

Now that I have told my life story, I will try to explain the pros & cons of chrome on aluminum.

THE PRO’S
Very high luster
Does not dull or fade
Easy to clean

THE CON’S
High cost
Long turn-around (if having something done you already own)
Short life (does flake, peel and chip)
No touch-ups (re-works only) which leads us back to high cost.

TO EXPLAIN
Chrome, as most people know it (like on bumpers), is really just a thin layer of copper then a slightly thicker layer of nickel then a flash (super thin) layer of chrome.
It is all done with electricity in liquids/chemicals not much warmer than your morning coffee. (About 140 deg. F.)

Aluminum is a relatively soft metal and is somewhat porous. If you happen to read about the gas cap with the chrome peeling due to vapors trapped underneath (another topic here in the Forum), that is a typical problem. However when I saw the back of the cap, it looked as if there was possibly machining oil still present when it was plated, another common problem.
More problems, in many cases, are due to the shape of the part to be plated.
Imagine chrome is like metal dust. If you were to sprinkle this metal dust over a magnet shaped like the letter “V”, the dust will cling to one side or the other and never make it to the bottom. This problem is overcome by making what is called an anode.
Anodes are lead bars connected to the positive electric pole and strategically placed to activate the plating process. Anodes aren’t always used where they should be because of the lengthy process required to set them up. This results in poor coverage in cracks and corners.

Since aluminum expands and contracts much more than chrome, under even mild temperature changes, the results are stress cracks that allow the weather to enter and do further damage. This is the primary reason for even the best of work that’s gone bad.

In regards to chrome over steel, well that’s a whole separate set of pros & cons.

I hope this wasn’t too boring and maybe even answered a question or two.

To everyone who has trusted me to polish his or her skid plate, I thank you very much! And Jason, thank you—this site rocks!

James
www.brightlee.com

[H2 Daddy]

Bright-Lee

Can chrome be removed from billit aluminum?

I would like to remove the chrome from my fuel door and then have it powder coated in flat black.

[Bright-Lee]

Yes, however,

In order for chrome to be removed, the gas cap would have to be completely disassembled. No pins, lock, ect… then back to a chrome shop.
The process is similar to the way chrome is applied only in reverse.

Sorry if that’s not exactly what you wanted to hear…Mo $ Mo $ Mo $

James
www.brightlee.com

[Bright-Lee]

Pores in aluminum trap and release gasses below the chrome. Corrosion on aluminum takes place more so when gasses and weather are trapped versus on just bare aluminum. Unprotected aluminum in a salt atmosphere will also show these white spots but are easily removed during routine maintaince. Anodizing is one of the best ways of protecting aluminum as far as coatings go. It is commonly used in the marine industry but you sacrifice some of the mirror finish.
I hope this has been helpful and thank you
James

[Darren]

Hi James,

Excellent synopsis of this subject.

On another issue: how does "black chroming" differ to normal chroming - you've no doubt seen components offered with a deep and dark chroming apperance - is this the same process or some sort of advanced powder coating???

Many thanks

Darren

[cubby]

A little help with the "black chrome"....

Black chrome is actually applied just like paint. It is a thin layer of real liquid metal on a product, sprayed on just like paint. It looks and feels as if it has been "chromed" not just painted. The finish is reflective and shines just like chrome, also like real chrome will not fade over time. Cost is probably as much a real chrome, but it comes in all metalic colors, gold, copper etc.
Hope this helps....


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Darren:
Hi James,

Excellent synopsis of this subject.

On another issue: how does "black chroming" differ to normal chroming - you've no doubt seen components offered with a deep and dark chroming apperance - is this the same process or some sort of advanced powder coating???

Many thanks

Darren<HR></BLOCKQUOTE>

[Bright-Lee]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>On another issue: how does "black chroming" differ to normal chroming <HR></BLOCKQUOTE>

Sorry it took a while for me to get to your answer.
It’s my understanding that black chrome is very much like hard chrome and is applied the same as chrome. Hard chrome is the 3rd and final coat of what most people in the biz refer to as “show chrome” or “triple plate” (copper, nickel, chrome).
By itself, hard chrome is not very shiny, unless polishing is performed before and after plating.

Anyways, back to the black,
Here is a page from one of my plating manuals that might help.

[Bright-Lee]

James
www.brightlee.com