Judging chrome plating types

[Randy R.]

Are hexavalent and trivalent chrome plating judged the same? I need bumpers rechromed.

Thank you,

Randy

[Joe R.]

Re: Judging crome plating types

Randy,

Bumpers are rechromed with triple plating. That's copper, nickel and chrome. Bumpers should pass all judging with this process.

JR

[Richard M.]

Re: Judging crome plating types

JR, YOU were up early. I was up about the same time!

Interesting question. I just researched the differences as I know nothing about either but I just learned something....

http://www.masterfinishco.com/specialty-finishes-and-process/trivalent-chromium-technology/

If this link ever departs, here it is for future reference below. Note what I highlighted in BOLD RED. It explains that Trivalent does a better job of depositing the chrome in recessed areas.

This would likely be ideal for 1956/1957 tail light housings as it would do a better job of eliminating shadows at the lower forward corners just below the red lens, which is a known problem for most plating shops. However......

For 1963 to 1967 front and rear bumpers, and 1968 to 1973 rear bumpers, typical original chrome in the 90 degree curved corners under the bumpers transitioning from horizontal to vertical was noticeably "shadowy". In judging, it is atypical to have full coverage chrome in these areas and may be noted as a deduction. It's happened to me on several restorations. Most folks want nice shiny chrome straight bumpers, but there's a negative for those that judge their cars if the chrome is too "nice".

Rich

Trivalent Chromium Technology


In most chrome plating baths the ions suspended in solution are hexavalent (Cr+6). Our new “green” trivalent chrome plating bath uses trivalent (Cr+3) ions for metal deposition. Hexavalent chromium is a known carcinogen which poses health risks to those who use this material in chrome plating. Hexavalent chrome also has environmental challenges that must be addressed by those who plate using this process.

New “green” trivalent chromium eliminates the health and environmental concerns associated with hexavalent chrome plating. In addition, trivalent chrome plating has better “throwing power”, allowing for more uniform deposit thicknesses on your product. Trivalent chrome does a better job of depositing metal in recessed areas and is less inclined to plate excessively thick deposits in high current density areas. Our new “green” trivalent chrome baths are setup to provide both bright “mirror” finishes and the new attractive dark color chromes.

MasterFinish is pleased to offer its customers both traditional hexavalent chrome and the new trivalent bright and dark chrome topcoats.

[Tony S.]

Re: Judging crome plating types

Randy, some well known exterior judges will deduct if the chrome is too well done. What does "too well done" mean? Ask your team leader for a clarification. Good luck.

[Randy R.]

Re: Judging crome plating types

I believe the colors of the two types is different. I would like to know if the color is judged.

Thank you,

Randy

[Harry S.]

Re: Judging chrome plating types

Usually it is just called over restored and it's a small deduction, as I recall maybe 1 point for the front and one for the back.

[Patrick H.]

Re: Judging chrome plating types

Hexavalent was the type used originally. If you're worried about it, just have them done that way. I suspect that is the way many locations still do the plating.

[Joe L.]

Re: Judging chrome plating types

Hexavalent was the type used originally. If you're worried about it, just have them done that way. I suspect that is the way many locations still do the plating.

Patrick------


It is and I would say that the VAST majority of platers use hexavalent chromium.

Here's an interesting bit of history: in the old days, chromium bearing solutions discharged into wastewater systems, rivers, oceans, etc. were regulated only to the extent that it was hexavalent chromium. So, companies that had hexavalent chromium in their wastewaters simply reduced it to the trivalent form (using a reducing agent such as sulfur dioxide) and discharged all they wanted to. That ended a LONG time ago when it was determined that while hexavalent chromium was the most toxic, trivalent chromium wasn't that far behind. So, now, wastewater discharges are regulated only as to TOTAL chromium, regardless of valence state.

Hexavalent chromium was widely used by industrial operations. The majority was not from plating, at least not traditional chrome plating. The majority was from its use as a conversion coating. Hexavalent chromium is a wonderful conversion coating which makes printed-on labels adhere tenaciously to cans without flaking off. This was the standard of the industry. So, for a very long time, beer and soda cans were treated to a conversion coating of hexavalent chrome before the label was printed on. That practice ended a LONG time ago. Guess why?

[Jeff P.]

Re: Judging chrome plating types

I just got back my chrome pieces from Librandi's in Pa. Absolute works of art. When car is ready for judging they will definitely take a hit. But it's about personal preference.

[Michael J.]

Re: Judging chrome plating types

I always think it interesting how different car organizations judge differently. In the Shelby and Mustang worlds (SAAC and MCA judging) there is no such thing as too nice, too shiny, etc. and you will be judged down if your finishes, like dichromate, chrome, phosphate, etc. are not just like jewelry and perfect. One reason I left them and appreciate NCRS more every meet.

[Tracy C.]

Re: Judging chrome plating types

Patrick------

... So, for a very long time, beer and soda cans were treated to a conversion coating of hexavalent chrome before the label was printed on. That practice ended a LONG time ago. Guess why?

I suspect the consumers drinking from said cans started coming up sick and even dying... Hex chrome is nasty stuff.

[Joe L.]

Re: Judging chrome plating types

I suspect the consumers drinking from said cans started coming up sick and even dying... Hex chrome is nasty stuff.

Tracy------


I don't know if the conversion coating was ever intended to get on the inside of the cans. However, I can't see how they could have ensured that none would. I don't know that anyone ever died from hexavalent chrome poisoning but I'll bet that some had their chromium levels raised a bit. This is the kind of thing that's rarely checked for in routine medical lab tests so who knows.........?

[Joe R.]

Re: Judging chrome plating types

Are hexavalent and trivalent chrome plating judged the same? I need bumpers rechromed.

Thank you,

Randy

Hi Randy:

Trivalent chrome has a slightly blue-ish tint that makes it look a bit different from the original hexavalent chrome that GM used in the 1960s. This difference is easy to see if samples of the two platings are placed side by side, but it's hard to notice looking at either one alone. My guess is that most judges would not notice the difference or, even if they noticed it, would not deduct for trivalent chrome.

It is my impression that due to environmental concerns, most chrome shops now use trivalent chrome instead of hexavalent chrome. A few can still do hexavalent chrome, though. I think Librandi(?) may be one of those.

[Russ S.]

Re: Judging chrome plating types

Guess why? The beer cost too much???

[Paul J.]

Re: Judging chrome plating types

See Post #7

https://www.forums.ncrs.org/showthread.php?102935-Seeking-thoughts-on-chrome-bumper-finish-for-1968&highlight=hexavalent+chrome