Register now to get rid of these ads!

Technical Prepping parts for chrome

Discussion in 'The Hokey Ass Message Board' started by Roothawg, Mar 12, 2024.

  1. 48ford
    Joined: Dec 15, 2001
    Posts: 469

    48ford
    Member

    This is the process ford used on there bumpers and gt wheels,
    The chrome plater was in Monroe Michigan
    It was 1/4 mile long,they first used it in 1957 and used it until they stopped plating bumpers( except for trucks) that business went to American bumper manufacturers out of Dearborn Michigan
    They had first cells that cleaned the bumper after they were stamped out in the press department,then it was copper strike
    Then a real shine copper,then every bumper was checked for imperfections,
    Then they were plated with white br***,
    Then nickel,
    Then finally chrome
    And final wash and inspection
     
    Desoto291Hemi and loudbang like this.
  2. goldmountain
    Joined: Jun 12, 2016
    Posts: 4,871

    goldmountain

    The platers wouldn't do copper on my nerf bars. Said the chemicals would get into the holes in the tubing I had for my license plate light would contaminate the chrome tank. Who am I to argue? It's magic.
     
  3. Roothawg
    Joined: Mar 14, 2001
    Posts: 26,060

    Roothawg
    Member

    So, what was your final grit on your prep?
     
  4. DDDenny
    Joined: Feb 6, 2015
    Posts: 22,592

    DDDenny
    Member
    from oregon

    Not all plating shops work the same way, especially since the EPA put a death grip on the industry with many shops closing, rightfully so due to the careless way some shops were disposing of their waste.
    A valuable note, ask the important questions, don't make ***umptions.
    I looked for quite a while for a nice set of original L79 Chevy rocker covers, the OEM covers never were show chrome and I was fine with that.
    I decided to look for a pair of painted covers that were worthy of chrome, I finally found a really nice pair at the Portland Swap Meet, I took them to one of the better local plating shops, it took nearly a month for them to get to them, I was ok with that part.
    What I did not expect was for the letters to lose their crispness, apparently the copper polisher was a bit overzelous on the buffing wheel and the letters came out kind of flattened and mushy looking.


    20170630_143459.jpg
     
    Last edited: Mar 13, 2024
    Desoto291Hemi and Roothawg like this.
  5. -Brent-
    Joined: Nov 20, 2006
    Posts: 7,867

    -Brent-
    Member

    One thing I was told beyond the obvious was to remove sharp edges.
     
    Roothawg likes this.
  6. Moriarity
    Joined: Apr 11, 2001
    Posts: 37,883

    Moriarity
    SUPER MODERATOR
    Staff Member

    80 grit, then 180 grit, then 320 followed by a sisal wheel on my baldor buffer. parts looked exactly like chrome before they were plated
     
  7. DDDenny
    Joined: Feb 6, 2015
    Posts: 22,592

    DDDenny
    Member
    from oregon

    I'm betting you didn't get that at Harbor Freight!
     
    Roothawg likes this.
  8. Roothawg
    Joined: Mar 14, 2001
    Posts: 26,060

    Roothawg
    Member

    So is there a particular compound that you used? I am always leery of contaminating the surface that is going to be plated.
     
  9. K13
    Joined: May 29, 2006
    Posts: 9,746

    K13
    Member

    Platers thoroughly clean parts with a caustic bath before they are plated. Platers can't afford to have their tanks contaminated.
     
  10. chickenridgerods
    Joined: Jul 22, 2003
    Posts: 1,557

    chickenridgerods
    Member
    from DSM, IA

    Are you calling industrial (hard chrome) platers or ones that specialize in cosmetic (decorative chrome) plating? Since the former are after the chrome's hardness and abrasion/wear properties. They don't care about how pretty the chrome looks, so they aren't going to use a copper underplating which would require subsequently thicker chrome layers to counterbalance the softness of the copper.
     
    Desoto291Hemi likes this.
  11. 38Chevy454
    Joined: Oct 19, 2001
    Posts: 6,802

    38Chevy454
    ALLIANCE MEMBER

    Agree the issue is cyanide copper plating bath vs acid copper bath. EPA not very accepting of cyanide baths, almost all plating shops conversion to acid copper. The nickel and chrome are both acid bath already. So easier to deal with the waste and clean up from the baths being all acid baths. Chrome baths are even mostly trivalent instead of hexavalent, for same hazardous materials reduction.

    Also good point that you want decorative chrome, not hard chrome. Decorative is copper, then nickel, then very thin chrome for appearance. AKA triple chrome.

    As for your prep, it's labor at the shop vs your time. The better you can get the parts, the better results and cost. Ideally you want a steel part that is polished like a mirror. The chrome plating will show any defects underneath the plating, unless you do the right preparation. Either by you or the shop.
     
    Just Gary likes this.
  12. bobss396
    Joined: Aug 27, 2008
    Posts: 18,756

    bobss396
    Member

    I bought mine around 1991 from MSC, have logged thousands of paid parts finishing on it. I use it mostly for polishing car chrome these days. I covered the exposed shaft and nut with shrink sleeve in case of an oopsie. I need to make up a shaft extender for at least one side.
     
  13. Roothawg
    Joined: Mar 14, 2001
    Posts: 26,060

    Roothawg
    Member

    No, we are in the heart of oilfield country so we have tons of industrial platers and powdercoaters. I'm talking about shops that do chrome for cars, semis etc. People just ***ume that everyone still uses copper, but they don't. Most shops that do offer copper call it "show chrome". It's substantially more expensive.
     
  14. Roothawg
    Joined: Mar 14, 2001
    Posts: 26,060

    Roothawg
    Member

    Found this on a guy's website. Has some good info in it.

    Stripping

    Before any repair work can be done to your part, all old surface finishes and contaminants must be removed. Grease and oil are removed in a parts washer that is serviced by a waste reclamation company. Paints and powder coating are removed by a hot tank stripper or by a dry blast method. Existing plating is removed by reverse plating in a 55 Baume solution comprised of sulfuric acid, water, copper sulfate, and glycerin. Rust is removed by blasting and/or pickling in hydrochloric acid. Whatever the requirement, Paul’s has several suitable removal methods available that are designed to remove the previous coating without damage to the substrate itself.


    Surface Preparation
    Plating only looks as good as the surface that it is applied to. Any deviation in the surface will mirror up and be magnified by the application of bright plating. Therefore, straightening, grinding, sanding, detailing, and buffing are extremely critical steps in determining the final outcome of the re-plated part. At Paul’s we take great pride in our ability to perform these tasks. Our ability to train new employees and retain our experienced ones is the prime reason that we have been able to grow, while providing consistent results project after project. It is ability (hand-eye coordination) and employee pride and determination that sets our work apart.


    Surface Restoration
    When deterioration is beyond removal by conventional sanding and buffing without risk to the substrate or its detail, the surface needs to be restored. This is accomplished by applying a substantial soft copper plating followed by a re-sanding. If required, remaining pitting, scratches, holes, or low areas are then silver soldered. The solder is then "cut down" to be level with the copper surface, and then the item is re-copper plated, enabling the entire surface, including the area previously soldered, to be polished. Depending upon inspection, the part will either have the copper plate reapplied and reworked, or have the final triple plate applied.


    Plating
    Cleaning - In order for plating to properly adhere, the substrate must be completely free of all foreign materials, such as oil, buffing compounds, finger prints, and soap films. At Paul’s the process begins in an ultrasonic cleaner tank containing a special hot buffered cleaner. This process removes virtually all the foreign materials, including buffing compounds, even down in threaded mounting holes. The part is then transferred to the scrub tank where it is meticulously hand washed to be certain that it is completely clean.

    After a thorough water rinse, the item is then racked or wired to a copper hook. It is the rack, or the hook & wire, that will allow the electrolization of the piece in the various plating tanks. The cleaning is continued at this point with a dip in a dilute acid & water bath, to ensure the removal of any soap residue, as well as to activate the molecular surface of the part. This dip is followed by a clean water rinse, and the item is now ready for its base coat in the copper strike tank.

    The copper strike covers down in recesses where other plating baths will not reach. The copper layer’s function is for adhesion so that the subsequent nickel plating or acid copper plating, which have an acidic base, will not react with the substrate, creating the potential for lack of adhesion (peeling).

    Upon completion of the strike and accompanying rinses, a layer of acid copper is plated. This is a soft, ductile, thick layer of copper used to resurface the part, to prepare it for further work in the polishing department. If further work is not required, the copper struck item goes to the nickel solution where a heavy layer of bright nickel is applied. The nickel is the main corrosion resistant or protective layer applied to the item. It is also the layer that provides the decorative "bright" effect to the item.

    The last step in the triple plate process is the chrome plate. This is a thin, translucent layer of a hard, weather resistant metal. The chrome’s main purpose is to prevent the tarnishing "dulling" of the bright nickel. After rinsing, the chromed object is ready for final inspection.
     
    williebill likes this.
  15. 36cab
    Joined: Dec 2, 2008
    Posts: 960

    36cab
    ALLIANCE MEMBER

    I worked in a chrome shop plating trampoline frames, gymnastic equipment and weight machines. We plated with a dull nickel followed by a bright nickel before the chrome. The dull nickel took the place of the copper plating, that we did not use, to help smooth out the substrate. Everything we plated was polished before going into the plating baths. For years it was a hexavalent chrome bath but towards the end of my employment there they switched to a trivalent chrome bath. although more environmentally friendly the trivalent finish was very disappointing compared to the hexavalent finish. On the gym equipment it wasn't so noticeable but on our personal car parts that we were allowed to chrome plate it was like night and day. I also learned early on that polishing is the most important step. Without a good polished finish on the substrate before going in the plating baths, the part could look like silver spray paint. I got pretty good at polishing my car parts, either using the company's polishing equipment or the polishing equipment I set up at home. As far the "light" plating in crevices and folds such as the flange on a valve cover, that is because it is a low density area that the electrically charged nickel and chrome has trouble getting into. The electrically charged nickel and chrome would want to go to the high density area first which sometimes would cause excessive plating (or as we would call it "treeing") in that area. We would build "robbers" to put next to these high density areas to eliminate the treeing. We would also build axillary anodes to put next to the low density area to help throw more nickel and chrome to that area. In a nut shell for decorative chrome plating of car parts - a good polishing job if the bare substrate is the key for good plating, the guy racking the parts with an understanding of low and high density areas is worth his weight in gold, use a plating shop that uses a copper strike and always use a plater that has a hexavalent bath.
     
  16. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 16,157

    Bandit Billy
    ALLIANCE MEMBER

    I clean and sand (down to 2000) most of the parts I take in for plating. One, it saves me a buck or two. Two, I get my stuff back faster. Three, I catch imperfections that I may be able to weld and file away.

    My chrome shop doesn't get rich off my onesy, twosy projects. The big jobs like semi manufacturers keep the doors open. So I try to make my stuff easy for them to get to.

    And they have no way to remove powder coating, so I take those pieces to the sand blaster or throw them on the barbie for a while and burn it off. The more you do to prep the pieces, the nicer they turn out too.
     
    seb fontana and Roothawg like this.
  17. Roothawg
    Joined: Mar 14, 2001
    Posts: 26,060

    Roothawg
    Member

    I still need to send you those Caddy covers.
     
    Bandit Billy likes this.
  18. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 16,157

    Bandit Billy
    ALLIANCE MEMBER

    Before or after you dimple them? :cool:
     
  19. Roothawg
    Joined: Mar 14, 2001
    Posts: 26,060

    Roothawg
    Member

    After....They are actually starting to flash rust. Been sitting there for a year on the bench.
     
  20. -Brent-
    Joined: Nov 20, 2006
    Posts: 7,867

    -Brent-
    Member

    Years back a HAMBer shared a polishing handbook .pdf - I'll look through my email and report back if I have it. It was good stuff.
     
  21. K13
    Joined: May 29, 2006
    Posts: 9,746

    K13
    Member

    Every chrome shop I have ever used has always offered both: Standard Chrome -no copper and Show Chrome- copper.
     
  22. alchemy
    Joined: Sep 27, 2002
    Posts: 22,785

    alchemy
    Member

  23. Moriarity
    Joined: Apr 11, 2001
    Posts: 37,883

    Moriarity
    SUPER MODERATOR
    Staff Member

    he has not logged on here since August 2008
     
  24. Roothawg
    Joined: Mar 14, 2001
    Posts: 26,060

    Roothawg
    Member

    So are you saying he’s not gonna reply?
     
    Bandit Billy likes this.
  25. alchemy
    Joined: Sep 27, 2002
    Posts: 22,785

    alchemy
    Member

    Last edited: Mar 14, 2024
  26. The37Kid
    Joined: Apr 30, 2004
    Posts: 32,555

    The37Kid
    Member

    After reading that my question is how did they wire these shafts for tank to tank transfer without effecting the machined surfaces?
     
  27. bobss396
    Joined: Aug 27, 2008
    Posts: 18,756

    bobss396
    Member

    These were really pivot pins, nothing more or less. Nothing went through them.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.