Decorative Chrome Plating Process - Chrome 101
Everything You Need To Know
From the February, 2009 issue of Custom Classic Trucks
By Dakota Wentz
Since the inception of the automobile, ornamentation in the form of chrome progressively grew and grew. It wasn't too long before automobiles began to look like luxurious pieces of rolling sculpture. It was a simple philosophy, the more chrome one had, the higher the stature. It wasn't until a man by the name of Edward Nicholas Cole-the mastermind behind the '55 Bel Air-decided to do more with less (chrome that is), that we see a decline in chrome highlighting automobiles. However, one thing has remained constant. Since the first auto designer hung that single piece of chrome, enthusiasts have been enamored with it.
In the genre of customized trucks, chrome is a staple in design. Whether it's stock chrome accessories, plating objects that were never chromed, or one's own ornamentation, we see chrome exhibited from truck to truck, coast to coast. Although chrome is enormously popular, we find that many don't know about chrome beyond the fact it's shiny and cool; and more importantly, what it takes to get something plated. To shed some light on the subject we contacted MJB Plating and Polishing, in Rialto, California, and discussed what chrome plating is and what you need to know before you send your parts off.
What Is Chrome?
Chromium, better known as chrome, is a chemical element found upon 91 other elements in the periodic table. Although chromium is a metal, it is not useful in a pure substance form. However, because of its durability, luster, and malleability it is a perfect metal to coat other metals-i.e. steel, brass, copper, and more-for either decorative, corrosion protection, or wear protection purposes-the latter being in industrial machinery.
What Is The Chrome Process?
"We get people in here all the time thinking we can chrome plate something in minutes by applying just some magic solution to their parts while they wait in the showroom," said Bill Felts owner of MJB Plating and Polishing. Unlike what many may think about chroming metal, objects are not dipped into a pot of melted chrome like a Fondue party. Instead, objects are chromed via a time-consuming process called electroplating. Electroplating is the process of using electrical current to reduce cations of a desired material-in this instance chromium-from a solution to coat a conductive object with a thin layer of the material.
Here's where this whole story...
Here's where this whole story got started, the grille for Project Get Shorty. The grille is comprised of five streamline tubing bars, which needed to be chromed. Like so many others, I just did what I thought would work, and because of it cost myself much more time and money. In order to clear my headlights, on three of the bars I had to cut half moons in them. When doing so, the tube expanded and I had to clamp and weld it back into place, but I couldn't quite get it exact. To make up for the low and high spots I filled the area with brass... If I only knew then what I know now.
I ground the heavy stuff down...
I ground the heavy stuff down with a grinder, but used a body file to work the rest of the brass.
Here you see the final product....
Here you see the final product. After the body file I used a red Scotch-Brite pad on an angle grinder to polish it somewhat smooth. Only problem here is, brass doesn't flow like lead, (and the more I tried to flow it, the hotter the metal became, which meant more warping-it was a giant runaround) and no matter how hard I tried I couldn't avoid several pin holes. At the time I thought no big deal, the chrome will blend it all in wrong .wrong, several copper build-ups are the only way!
Once at MJB, Joe Gonzales...
Once at MJB, Joe Gonzales began polishing the parts through the various steps.
Here's an up close look at...
Here's an up close look at the material used to polish the pieces. This is the 150 grit aluminum oxide Emery that outfits the polishing wheels. When touched, it feels almost like powder, but it does wonders.
So fresh and so clean, the...
So fresh and so clean, the only way to describe the freshly polished grille bars.
The Chrome We Know
When it comes to the chrome we know, show-quality chrome, a renowned job by industry standards is referred to as triple plating. Chroming objects isn't a quick process; in fact it's much like a paintjob. The actual layer of chrome is exceptionally thin, measured in millionths of an inch rather than in thousandths, therefore work must be put into parts to ensure a smooth and even finish. Hours of physical work is spent massaging objects to perfection, followed by several "coats" of various metals. When parts are dropped off at a quality chrome shop, such as MJB, first they are sent to the polishing room. Parts start off with a trip on a 150 grit aluminum oxide Emery wheel to get roughed out. From there the parts are then followed up with 180 grit Turkish Emery for fine polishing. The final step in the process is a super fine Sisal buff. At this point the raw material is suitable for plating. Once polished, the parts enter the first step in the triple-plating process, a 120 degree copper bath. The parts are dropped into the copper tank for an hour-the longer they are left in, the higher the copper buildup. The copper acts like a coat of primer in a paintjob, by providing a basecoat to help smooth any minor blemishes. Once plated in copper, the parts are then buffed with a fine cloth-think of this process as blocking a primered truck. If the parts are defect free they're sent on their way. However, if the parts still have pin holes, scratches, divots, etc. they get another dip in the copper and are re-buffed, much like laying down several coats of primer on a paintjob. This process can be repeated as many times as needed, however, each time the price increases-more labor and material equals higher cost. Parts are then moved to the second phase in the plating procedure, nickel plating. The objects are submerged into a 135 degree nickel bath for an hour. The nickel plating provides smoothness, corrosion resistance, and a great deal of the reflectivity. In fact, to the untrained eye, if one was to see a freshly nickel plated object they would probably assume that is has been chromed; however that's not the case. (We'll get back to this in a minute.) The last step in the triple-plating process is really what it's all about, a chrome bath. Unlike the pretty intense soaking a copper or nickel bath takes, objects are dipped in a chrome bath for roughly two minutes! Once they leave the chrome bath they're finished. Now some of you are probably wondering, "Why chrome-plate something if the nickel looks almost the same?" Well, here's why. For starters, nickel won't hold up. Shortly after nickel enters the elements it begins to oxidize and lose its luster, whereas chrome will hold up and keep its finish for years. Nickel is also a softer metal, prone to scratches and such. Once again, chrome is a much harder metal that is durable. Along with that, the finish nickel leaves is that of a yellowish cast. As for chrome, it provides a deep, radiant bluish cast that we have all come to know and love.
Don't Get Hosed
When it comes to chrome plating, there are several things to always keep in mind. For starters, a good rule of thumb is what Bill advised us on, "When it comes to the chrome industry, the process is pretty much the same throughout. The only way to cut cost is to reduce one of three things; either cut the process from a triple-plate process to a two-step process with just a nickel and chrome bath, reduce the time each object is submerged in one of the necessary plating baths, or skimp on the polishing prep work at the beginning. Although cutting corners will work, when you leave out any of the necessary steps you'll end up with a sub-par plating job. Always ask questions about a chrome shop's procedure before you employ them, because not following through with the necessary steps is the difference between a quality and non-quality chrome job." Basically it's a steak vs. hamburger type of situation.
When sending off things to...
When sending off things to get chromed, be sure to specify anything that doesn't need to be chromed, for example, bolt threads, tolerance holes, and more.
Electroplating 101: copper,...
Electroplating 101: copper, nickel, and chrome tanks all look like this, a tank filled with a solution. Above the tank are two copper bars, which act as the ground in an electrical circuit.
Along the sides of the tank...
Along the sides of the tank are two poles with bags hung on them. The two poles are essentially "hot wires" due to the fact the current runs through these poles...
When repainting a car one can get away with scuffing up old paint and applying a new finish, however, there is only one way to re-chrome old bumpers, emblems, trim, and the like. Chrome can't be laid over the top of chrome, even if the base chrome is decent. Instead, the part must take a trip to a muriatic acid bath where the previous coat is completely removed. At that point the object will go through the chroming process all over again. By the way, don't try this step in your backyard; let a chrome shop do it!
Knowledge Is Power
So far we've covered what chrome is, and what the process is. What we haven't delved into is what you need to know about fabricating your own pieces that will eventually visit a chrome shop. Like we said before, the entire triple-plating process is not a heavy buildup. In fact, it's minuscule, hundredths of an inch thick when it's all done. Therefore, it's crucial to get ones metal as smooth and even as possible before it's sent off-for two reasons. For starters, looks. Chrome is like a mirror, and any defect will be magnified. For this reason make sure all welds are ground smooth and pot-hole free, any and all pin holes, divots, valleys-whatever you want to call them-need to be removed. Trying to chrome over these little miscues is like implanting a prism right in the middle of your ornamentation, and not in a good way! Add dabs of weld to any trouble spots and then grind it back down to ensure everything is following an even keel. The second reason to ensure that everything is smooth is cold hard cash. Remember, chrome plating takes a lot of polishing. The more the chrome shop has to polish your pieces to perfection, the more you're going to pay. Take the time to grind and file your metal to as close to perfection as you can get it. Why spend more when you can take a few extra hours at home to make it right?
Another thing to keep in mind is to not over grind. For instance, take shaved bumpers for example. According to MJB, one thing they often see is guys shaving their bumpers, but over grinding their welds to the point it creates a low spot. On one hand it's good because all the imperfections of the weld is ground smooth with the bumper, but remember, every action has a reaction. And the reaction here is a low spot that will wave at you like the homecoming queen in a parade. If you're unsure about your skills to create an even-flowing piece, then grind your welds close, but leave a little bit of a raised weld for the chrome shop to do the rest.
In the case that one has to fill or fix any defects, such as low spots, and tacks of weld are out of the question, there are options. However, it will jack the price up. For small areas, 1x1-inch areas, one can use brass brazing rod or bronze silica rod to fill low spots and repair imperfections. It is perfectly OK to chrome either of these metals; however, where the extra expense comes into effect is in the copper baths. The reason one would use brazing rod or bronze silica on their parts is because it will flow and grind much easier than steel, which makes fixing an imperfection that much easier. Yet it is because of the soft property of these ores that makes things more expensive. When the chrome shop goes to polish the object the softer metal will dissipate much faster, which could leave the imprint of the area in the finished product. Therefore, the chrome shop will build up a layer or two of copper to ensure a nice basecoat with an even finish, resulting in a hike of the price.
...The bags along the poles...
...The bags along the poles are filled with 1x1-inch squares of copper, nickel or chrome. (see above)
Here's how it all works. Parts...
Here's how it all works. Parts are strung up with copper wires and hooks (for conductance), and hung on the ground poles. Once down in the solution, the electrical current begins breaking down the 1x1-inch pieces of metal into minute pieces that fill the solution with thousands of tiny pieces. The minute pieces are then drawn to the current of the objects hanging on the ground poles, which in turn plates the piece in the desired metal.
Another valuable lesson I...
Another valuable lesson I learned is that pieces welded closed are the most troublesome-because A. they tend to float, and B. they run the risk of taking on solution. If any solution from the previous tanks seeps in through pin holes, there is a risk it will seep out in one of the other plating tanks; long story short; chrome shops won't take that chance. In my case I ended up having to put drain slots at the back of my bars, that way the bars could be drained before they entered the next bath. Once again, this is why it's always a good idea to give a call to guys like MJB with these scenarios-Bill was actually the one who helped me out with the drain solution.
In cases where a larger area needs to be fixed it's also possible to use lead. But yet again, one uses lead because it's soft and easy to work with, even softer than brass or bronze. When chroming over lead, an even bigger coat of copper needs to be built up, which means the price will go up that much more. If you're in a situation where you know a filler metal is going to have to be used it's a good idea to contact your local chrome shop beforehand, they may be able to help you out with some tips, suggestions and alternative options that may lower the overall cost. Bill and Joe at MJB are more than willing to help customers reach a solution, which could save you a lot of time and money in the long run.
Hopefully by now you have a better understanding of what chrome is, and how shops go about it. If nothing else, we at least hope you now have an understanding of why getting items chromed can be quite the pretty penny! Like all finish work, it's a tedious job that requires the proper steps and that's the bottom line.
Here is the grille in the...
Here is the grille in the freshly polished copper stage. When it comes to polishing copper, the chrome shop can actually "move" the copper to troublesome areas to help alleviate the problem, this process is called copper mushing...
...Even after Joe worked some...
...Even after Joe worked some troublesome areas on my pieces, there were still a few pin holes, which means it's back to the tank.
In the end MJB got the situation...
In the end MJB got the situation handled, and the grille turned out great. However, it was a long time coming, due to the fact we were fighting my mistakes along the way. If you're getting ready to embark on something of this nature, I would strongly suggest giving either Bill or Joe a call. It may be the most important call you ever make ... or at least in terms of getting your items chromed!