On an effort to bring our readers the most in-depth and important tech articles in the industry, we sent our ace undercover lens man Spanky McDraggit to procure some spy footage of what goes into chroming truck parts. Never before has anyone attempted such a feat. Spanky had to go in full-blown, 007 espionage-style to score these rare photos from Baker Metal Polishing in Whittier, California.
After examining the evidence, we now understand why chrome-plating is so expensive. This is some of the most dangerous, caustic, and toxic work that you can have done to your mini. The process takes hours and involves a grip of dangerous chemicals. The governmental regulation of chroming is extremely restrictive, thus driving up the price for quality work. Also, this is a labor-intensive process. We have newfound respect for the folks who put the time in such a dangerous environment to bring us shiny parts for our rides. For an exclusive look into chrome-plating, check out the spy photos. If you would like the shiny touch put on your parts, contact Baker Metal Polishing using the information listed in the source box.
The process for chroming varies depending on the materials being chromed. If you are having aluminum parts chromed, such as a valve cover or fuel-injection manifold, then the parts will be polished, cleaned, and plated as follows:
2. Vapor de-greaser
3. Caustic cleaner (electro)
4. Dioxides (aluminum)
5. Etching solution (aluminum)
6. Rinse (water)
8. Rinse (water)
9. Copper strike
10. Ni add nickel
11. Bright nickel
12. Rinse (water)
14. Hex chrome
Each one of these steps requires that the parts be dipped in a separate tank anywhere from a few seconds to an hour.
The process for chroming steel parts such as control arms, link bars, and brackets is as follows:
2. Vapor de-greaser
3. Electro cleaner
4. Rinse (water)
6. Rinse (water)
7. Copper striker
8. Rinse (water)
11. Acid copper (steel)
13. Semi nickel
Other considerations you should make when having your parts sent out for chroming is the type of plating the shop is using. The two most popular types are trivalent and hexavalent plating. Trivalent plating is a cheaper process that sometimes leaves dull white areas around holes and cavities in your parts. Hexavalent is the way to go, although it is more expensive. Another thing we learned is that triple chrome-plating does not mean that your parts go into the chrome tank three times. Triple chrome-plating refers to the process of plating the parts separately with copper, nickel, and finally chrome-plating. Be sure to specify this process if you want a show-quality finish. You can save money and have them skip the copper portion of the process, but then your parts will not look as smooth, shiny, and beautiful.
1. A steel part such as this...
1. A steel part such as this air intake adapter had to be stripped of all the paint prior to chroming. Doing this yourself before you bring the part to the shop will save you money. The paint was sanded off carefully, and only fine-grade paper was used because the more scratches put in the surface, the more polishing would have to be done later. This would drive the price up.
2. This was where things got...
2. This was where things got expensive. The better job done polishing the part, the better it will look in chrome. Polishing this aluminum manifold took about two hours because of all the curves and crevices.
3. Here you can see one intake...
3. Here you can see one intake runner fully polished. It almost looks like chrome, but as we all know, the shine will not last unless it is chrome-plated.
4. After the parts were fully...
4. After the parts were fully polished, they were placed on rubber-coated metal racks that would be used to place the parts into various hot tanks.
5. Here we see an aluminum...
5. Here we see an aluminum part being cleaned in a vapor de-greaser tank. This cleaned the exterior of dirt.
6. This is a shot of a worker...
6. This is a shot of a worker turning on the electricity to a tank containing a caustic cleaning solution.
7. The caustic cleaning solution...
7. The caustic cleaning solution was heated to about 115 degrees Fahrenheit and charged with AC current. This part was dipped in the caustic solution for about 10 minutes.
8. Next, the part was dipped...
8. Next, the part was dipped in a sulfuric acid solution for approximately one minute. The acid cleaned all trace oils and fingerprints from the metal.
9. Then the part was rinsed...
9. Then the part was rinsed in water.
10. The part was submersed...
10. The part was submersed in a tank filled with an alloy zincate solution. This is an etching solution that prepped the part for the copper plating that was to follow.
11. This is what the part...
11. This is what the part looks like after leaving the alloy zincate tank prior to rinsing.
12. Next, the part was po...
12. Next, the part was polished.
13. Here is the area where...
13. Here is the area where the parts were polished. Dirty! How would you like to work here all day long?
14. After being cleaned extensively...
14. After being cleaned extensively again, the parts were dipped into an acid copper tank. This tank was heated to 80 degrees Fahrenheit and is composed of a 10 percent sulfuric acid and 90 percent copper solution. You don't want to get this stuff on your skin.
15. The part was then rinsed...
15. The part was then rinsed with water. Look at the pretty colors.
16. The part went from the...
16. The part went from the rinsing tank to the first nickel tank. This is an Ni Nickel tank filled with a heated solution of nickel sulfate, nickel chloride, and boric acid. Again, this stuff would hurt really bad if you touched it.
17. In this photo, you can...
17. In this photo, you can see the pieces of nickel that sit inside of the bag. The part hung on a metal rod in the middle of the tank and was electrically charged with AC current. The current drew the nickel from the bag to the part and plated it. Cool, huh?
18. After being pulled from...
18. After being pulled from the first nickel tank, the part was immediately placed into a bright electrolytic nickel tank and left there for about one hour.
19. The part was then put...
19. The part was then put into a rinsing tank and cleaned. It was then put into a different tank filled with an activator solution that changed the color of the part to a dull silver. It was now ready to be put in the chrome tank.
20. This was the hexavalent...
20. This was the hexavalent chromic acid bath tank. Believe it or not, out of this dirty, rusty-looking solution comes the most beautiful chrome-plated parts. There are other types of chrome-plating such as trivalent plating, but none equal the quality of a hexavalent one.
21. The part was placed into...
21. The part was placed into the tank for just less than a minute and came out with an orange appearance.
22. The part was then placed...
22. The part was then placed for a few seconds in three separate chrome drag-out tanks filled with water. By the time it reached the third tank, the orange appearance had disappeared and the beautiful chrome appearance was seen. It was then rinsed thoroughly with water to remove any leftover hexavalent chromic acid chemicals. If any of these chemicals were to drain out of a cavity in the part onto the surface of the chrome later, it would ruin it.
23. Once the parts dried (about...
23. Once the parts dried (about five minutes), they were reinstalled and we had a beautiful engine.