Wednesday, January 21, 2009

10 Facts About Chrome

We are all victims of calling shiny metal Chrome. But is it? Here are some facts about the shiny, almost mirror like metal and what you need to know If you want something coated in it...

What is Chrome..?

Chrome is slang for Chromium. Chrome is a metal. Things are never made of solid chrome. Rather, when you hear that something is chrome, what is really meant is that there is a thin layer of chrome, a plating of chrome, on the object (the bulk of the object usually being steel, but occasionally aluminum, brass, copper, plastic, or stainless steel).

A cause of occasional confusion is the fact that people tend to describe any shiny finish as "chrome" even when it really has nothing to do with chromium. For example, brightly polished aluminum motorcycle parts are sometimes called 'chrome' by the lay person.

Indeed it's not always easy to tell chrome plating from other finishes if the parts are not side by side. When a decorative chrome electroplated finish sits right next to another bright finish, however, the other finish usually won't compare very favorably :-)

Chrome plating is more reflective (brighter), bluer and more specular (the reflection is deeper, less distorted, more like a mirror) than other finishes. Put one end of a yardstick against a bright finish, and see how many inches of numbers you can clearly read in the reflection -- you can clearly see the clouds in the sky reflected in chrome plating. And there's a hard to define "glint" to top quality chrome plating that nothing else has.

What's the difference between "Chrome Plating", "Chrome Electroplating", "Chrome Dipping", "Chroming", etc.?

Nothing. Chrome is always applied by electroplating, it is never melted onto parts in the fashion of chocolate on strawberries, or applied in any other way than by electroplating.

Is all chrome plating about the same, then?

Not quite. There are two different general applications for chrome plating: "hard chrome plating" (sometimes called 'engineering chrome plating') and "decorative chrome plating".

Hard Chrome Plating

Most people would not be very familiar with hard chrome plating. Hard chrome plating or Industrial Chrome is chrome plating that has been applied as a fairly heavy coating (usually measured in thousandths of an inch) for wear resistance, lubricity, oil retention, and other 'wear' purposes. Some examples would be rollers, piston rings or motorcycle fork stanchions etc. 'Hard chrome' is not really harder than other chrome plating, it is called hard chromium because it is thick enough that a hardness measurement can be performed on it, whereas decorative chrome plating is only millionths of an inch thick and will break like an eggshell if a hardness test is conducted, so its hardness can't really be measured directly.
Hard Chroming is not as reflective as 'decorative chrome plating' and is not a finish you would want on say a bumper or a wheel.

Decorative Chrome Plating

Decorative chrome plating is sometimes called nickel-chrome plating because it always involves electroplating nickel onto the object before plating the chrome (it sometimes also involves electroplating copper onto the object before the nickel, too). The nickel plating provides the smoothness, much of the corrosion resistance, and most of the reflectivity. The chrome plating is exceptionally thin, measured in millionths of an inch rather than in thousandths.

When you look at a decorative chrome plated surface, such as a chrome plated wheel or car bumper, most of what you are seeing is actually the effects of the nickel plating. The chrome adds a bluish cast (compared to the somewhat yellowish cast of nickel), protects the nickel against tarnish, minimizes scratching, and symbiotically contributes to corrosion resistance. But the point is, without the brilliant leveled nickel undercoating, you would not have a reflective, decorative surface.

Buzzwords: "Chrome Plating", "Double Nickel-Chrome", "Show chrome", "Triple Chrome"

"Show chrome" probably means chrome that is good enough to be on a winning entry in a car show. Chrome-lovers believe that the key to "show chrome" is to copper plate the item first and then buff the copper to a full lustre before starting the nickel plating.

Whether you start with bare steel or buffed copper, at least two layers of plating follow -- a layer of nickel and a layer of chrome.

Salespeople are always looking for advantage, and they will use any good-sounding terms they can get away with! There are no laws that define what triple chrome plating actually means, so salespeople will be prone to call their service "triple chrome plating" if there are a total of 3 layers of any kind of plating, or "quadruple chrome plating" if there are 4. So those terms mean little.

Chrome plating is hardly a matter of dipping an article into a tank, it is a long involved process that often starts with tedious polishing and buffing, then cleaning and acid dipping, zincating (if the part is aluminum), and copper plating. For top reflectivity "Show Chrome", this will be followed by buffing of the copper for perfect smoothness, cleaning and acid dipping again, and plating more copper, then two or three different types of nickel plating, all before the chrome plating is done. Rinsing is required between every step.

Restoration Work

When an item needs "rechroming", understand what is really involved: stripping the chrome, stripping the nickel (and the copper if applicable), then polishing out all of the scratches and blemishes (they can't be plated over and any scratches will show after plating), then plating with copper and "mush buffing" to squash copper into any tiny pits, then starting the whole process described above.

Unfortunately, simply replating an old piece may cost several times what a replacement would cost. It's the old story of labor cost. The new item requires far less prep work, and an operator or machine can handle dozens of identical parts at the same time whereas a mix of old parts cannot be processed simultaneously, but must be processed one item at a time. If a plater has to spend a whole day on your parts, don't expect it to cost less than what a plumber or mechanic would charge you for a day of their time. Follow the link if you're looking for a list of some chrome plating shops serving the public.

Peeling chrome?

If your chrome plating is peeling, this is virtually always a manufacturing defect due to insufficient adhesion of the plating to the substrate. Although exposure conditions can certainly harm chrome, and discolor it or make it pit, they won't make it peel! It can be very difficult for a plating shop to get good adhesion on some things (most commonly on alloy wheels because they are not pure aluminum), but if they can't do it they shouldn't sell it. If your parts have peeling chrome, you should complain and not be deterred by nonsense about chemicals in your garage, how frequently you wash the wheels, etc. We'll say it again, we're that sure: peeling chrome is virtually always a plating defect. Follow the link if you're looking for a professional chrome plating shop serving the public.

An Interesting Fact...

Until the plant was shut down in the late 1990s, Cadillac's main manufacturing and assembly plant (located in Detroit, Michigan) won awards for the best chrome plating line (including bumpers) in the world for over 50 consecutive years of operation.

Where can you get Chrome Plating done then?

Follow the link if you're looking for a list of professional chrome plating shop serving the public UK & Europe


  1. And i thought chrome was just a quick dip ;) nice article!

  2. Most People think Chroming or Chrome is just a dip in a bucket or some shiny metallic chemical - I will be posting a blog describing the chrome plating/chroming process soon :-)

  3. Hi, Im restoring an old Honda 750, much of the chrome on the engine covers has peeled badly, whats the easest way to removed the rest of the chrome, so i can polish the alloy?

  4. The chrome can be stripped using simple paint stripper such as Nitromors - But this will only strip off the Chrome which is just a thin layer. Below the chrome you will have Nickel and Then possibly Copper. Some metal polishers would polish off the Plates but this would mean linishing it with a hard grit and may make a lot of work especially if your not a skilled polisher - The best solution is let a chrome shop strip them for you as this will leave the metal below in top notch condition and make light work of the polishing job. If they are not pitted or scratched using a mop with the right choice of compounds will soon get the shine on :)

  5. Suppose Ashford Chroming were asked to chromium plate brass vintage car parts ( about fifty years old) to give a quality similar to that originally applied, what thickness of underlying nickel would they recommend and would it be a single layer.

  6. hi, could you chrome normal alloy wheels? many thanks

  7. I would like to add that while chrome is the finish of choice for any high gloss / shine finish (ie. automotive, motorcycle industry, bathroom faucets etc.), the hexavalent chrome baths are some of the most hazardous and polluting of all plating baths. It is little known that there are many environmentally friendly alternatives to traditional chrome plating. These chrome alternatives are just as bright as hexavalent chrome and have equal or better physical properties. For more information on Alternative Chrome Plating please visit Spectrum Metal Finishing, Inc. at Spectrum Metal Finishing, Inc.

  8. chroming vs stainless steel polishing.
    Chroming has the disadvantage to peel from the under layer and has to be stripped off before it can be re-chromed, while stainless steel has the advantage that it has a self healing surface that can be re-polished.

  9. Nice, Metal is everywhere in a modern day home. From faucets to refrigerators and fixtures to furniture, it makes at least a small appearance in every room of the house.

  10. I am very much interested in metal finishing, coating etc as it gives pleasant appearance to our furniture...recently, while browsing i have come across this Greenwich metal finishing in new york

  11. Ok I have a friend that works in a place that does the electro chrome thing. Problem is there are a great deal of defects that they notice. Was really wondering what color to best view the parts through (tinted safety glasses) any suggestions?