Maybe Roger knows the answer............

[cpm9ball]

........but if anyone else does, please feel free to chime in.

 

http://www.coinnews.net/2013/04/09/u-s-mint-at-san-francisco-preparing-coin-dies/

 

I was reading the article, above, posted two days ago about the proof die-making process. In it, the author mentions that until the "PVD" process was developed for chrome-plating the dies, the Mint used hexavalent chromium to harden the dies.

 

My question is: Does anyone know when the Mint stopped using hexavalent chromium?

 

Chris

[RWB]

Sorry – I’m not of much help on this question.

 

In the period I've examined the mint was still using chemical plating into the 1950s. During the late 30s and early 40s proof dies were chromium plated but the work was done by the National Bureau of Standards in Washington DC. Some 1943 cent dies were also chromium plated to reduce filling of design elements by zinc dust.

 

I leave all the "modern stuff" to those with an interest in the technology.

 

[cpm9ball]

Roger, I'm curious about this because hexavalent chromium is a dangerous carcinogen.

 

Chris

[shirohniichan]

Roger, I'm curious about this because hexavalent chromium is a dangerous carcinogen.

 

Chris

 

Attention California Residents:

 

California Proposition 65 (also known as the Safe Drinking Water and Toxic Enforcement Act of 1986) requires a warning to California consumers for any product that contains certain chemicals which are known to cause cancer, birth defects or other reproductive harm. Accordingly, USMINT.gov is informing you as follows:

 

WARNING: Proof coins are a product of processes that may contain chemicals known to the State of California to cause cancer, birth defects or other reproductive harm.

 

USMINT.gov will include a notice containing such a warning with all products shipped by USMINT.gov to California addresses. We have also directed our suppliers that they must comply with California Proposition 65 and provide specific warning with all products produced by USMINT.gov and shipped by our suppliers to California addresses which fall within the requirements of Proposition 65.

[Coindude]

The proof minting process got a heck of a lot better in the early 1970s so I would suspect sometime around then.

[cpm9ball]

Roger, I'm curious about this because hexavalent chromium is a dangerous carcinogen.

 

Chris

 

Attention California Residents:

 

California Proposition 65 (also known as the Safe Drinking Water and Toxic Enforcement Act of 1986) requires a warning to California consumers for any product that contains certain chemicals which are known to cause cancer, birth defects or other reproductive harm. Accordingly, USMINT.gov is informing you as follows:

 

WARNING: Proof coins are a product of processes that may contain chemicals known to the State of California to cause cancer, birth defects or other reproductive harm.

 

USMINT.gov will include a notice containing such a warning with all products shipped by USMINT.gov to California addresses. We have also directed our suppliers that they must comply with California Proposition 65 and provide specific warning with all products produced by USMINT.gov and shipped by our suppliers to California addresses which fall within the requirements of Proposition 65.

 

Hah! What a joke!

 

Dear coin collector:

 

Enclosed, you will find your 1987 Proof Sets struck at the San Francisco Mint.

 

In accordance with California Proposition 65 of 1986, we must advise you that the dies for these proof coins were processed using hexavalent chromium, a dangerous carcinogen.

 

Please do not be alarmed, handling the coins will pose no risk to you or your family, unless if by chance, one of your children should swallow a few dozen sets.

 

Thank you for your patronage,

 

Anonymous Mint Employee

[MorganMan]

Yeah, the sooner the big one hits and that place breaks off into the Pacific, the better we will all be. They will soon ban living out there.

 

For the troublemakers:

 

MM

[cpm9ball]

Yeah, the sooner the big one hits and that place breaks off into the Pacific, the better we will all be. They will soon ban living out there.

 

For the troublemakers:

 

MM

 

If that happened, the kids from Million Dollar Listing would have a lot more beachfront property to sell.

 

Chris

[RWB]

Hexavalent chromium was part of several solutions the mint tested in early 1943 in their search for a way to darken the new coins. That was supposed to avoid confusion with the dime....

[TonerGuy]

Once Erin Brockovich sued the US Mint...

[cpm9ball]

Once Erin Brockovich sued the US Mint...

 

I'm really curious to know what the SF Mint did with all of the HC waste. That was decades before the PG&E case. So, what did they do with it?

 

Chris

[jpcienkus]

Roger, I'm curious about this because hexavalent chromium is a dangerous carcinogen.

 

Chris

 

I used to work for a metal finishing company that plated Hexavalent Chrome. It's the bluer chrome. The darker chrome is trivalent.

 

Hexavalent in it's liquid state appears orange. It's considered toxic.