Black coated gold pins after HCl bath

[gentleman5926]

Hello all. I have Hokes book and have been watching/ reading. I decided to attempt to clean off the solder from the gold pins I had by soaking in an HCl bath to dissolve just the solder (was my plan anyway). I placed the contaminated pins in a mason jar outside (in South Mississippi sun, etc) and covered them with HCl and then doubled that amount of HCl given the amount of Solder on the pins. I noticed several hours later that my pins looked like they were either being coated in black "stuff" or something else was happening. I left it alone as this was a test. Two days have elapsed and today I decanted the solution off, and rinsed the remaining 'debris' off using just tap water since I figured something horrible had gone wrong. Then I noticed that in actuality the gold pins were still there but were covered in a dark gray coating. I also noticed that when I was rinsing the pins the water was becoming white (cloudy... Silver??) but this was ordinary chlorinated city water so I really have no idea what caused what (BTW, the cloud of white left a white 'scum' on the inside of the mason jar. I have both the HCl and the rinse water set aside until I get a little further info. Sorry for the long post here, today is my first action on this forum.

 

[Barren Realms 007]

Sounds more than likely you were dealing with tin. Do a search and read up on tin.

 

[gentleman5926]

Thanks sir, that was all the info I needed. Just a general direction to head. Will be deleting this post tonight.

 

[jimdoc]

Thanks sir, that was all the info I needed. Just a general direction to head. Will be deleting this post tonight.

You do not delete posts here on this forum, that is up to the moderators.

 

[FrugalRefiner]

As jimdoc said, deleting posts is against forum rules. There is a link to the rules at the top of every page. Others can learn from this thread in the future.

The white precipitate when you rinsed wasn't silver, it was copper(I) chloride.

Dave

 

[patnor1011]

Sounds more than likely you were dealing with tin. Do a search and read up on tin.

Tin will dissolve in HCl. What he got there is more than likely copper chloride.

 

[Barren Realms 007]

Sounds more than likely you were dealing with tin. Do a search and read up on tin.

Tin will dissolve in HCl. What he got there is more than likely copper chloride.

That is possible. He didn't state what the color of his solution was.

(BTW, the cloud of white left a white 'scum' on the inside of the mason jar


This comment in his post was why I said it was possible tin.

One of those times where more information from the poster would have helped. :mrgreen:

Thanks Pat. 8)

 

[gentleman5926]

Okay. First, I want to apologize about deleting a previous comment in this thread. In many others I have removed useless posts and carried that over to here. I, today before I read these comments, read the rules concerning posts and not deleting the posts or any portion thereof as well as NOT editing to change the tone of the original posts. I apolgize. Secondly, some more info and curious stuff.
The "pins" were from an old HI-FI radio and tested positive for gold content using a standard scratch/acid test with "internet" testing solutions purchased online. They had solder (and unknown to me, copper wire underneath the solder) which I was trying to dissolve and remove before processing any gold content. The first solution was a slight (VERY slight) yellow in hue but clear other than that. I have it still and it does not test positive with Tin (II) Chloride for any gold content.
I rinsed the pins several times with distilled water and saved that solution also, as well as removing all other metal contamination I could manually. Which brings me to another question:

In both the RINSE water AND my Stannous solution I am making, I have grown clear/white crystals that are linear. The solder I used for the Stannous was 99.3% Tin/ .7% copper and the HCl brand is Transchem with only Hydrogen Chloride and water as ingredients.

 

[Marcel]

I have grown clear/white crystals that are linear.

Should be lead chloride

 

[gentleman5926]

Thanks for the input. I also, after reading some posts here, realized that I had underestimated the HCl I needed for the amount of tin solder I was dissolving. Problem fixed now and completed. I haven't got any gold solution yet to test, that is my next project. Appreciate all your inputs. I read a post that said Hobby Lobby had gold leaf for making a gold solution to test. I can't find it listed as REAL gold leaf, only imitation.

 

[Barren Realms 007]

Thanks for the input. I also, after reading some posts here, realized that I had underestimated the HCl I needed for the amount of tin solder I was dissolving. Problem fixed now and completed. I haven't got any gold solution yet to test, that is my next project. Appreciate all your inputs. I read a post that said Hobby Lobby had gold leaf for making a gold solution to test. I can't find it listed as REAL gold leaf, only imitation.

I don't think it would be real gold from Hobby Lobby but maybe someone can test some and get the answer to that question.

 

[UncleBenBen]

The wife and I do a bit of catering from time to time. Back around 2006 we catered her parents' 50th wedding anniversary. The 'Golden Anniversary'. We ordered some gold leaf online to put on the cake. It was packaged as food grade and labeled 3N+. I don't remember what we paid but it was reasonable.

 

[ahmadbayoumi]

Thanks for the input. I also, after reading some posts here, realized that I had underestimated the HCl I needed for the amount of tin solder I was dissolving. Problem fixed now and completed. I haven't got any gold solution yet to test, that is my next project. Appreciate all your inputs. I read a post that said Hobby Lobby had gold leaf for making a gold solution to test. I can't find it listed as REAL gold leaf, only imitation.

gentleman5926,

Would you pls share with us what you have done to overcome this issue as I\m facing the same now ?