So I have these partially plated pins that I got awhile back. They may be only partially covered in Gold but the part that is covered in gold looks pretty good. So I determined that they were non-magnetic and I thought maybe a slow AP process would be helpful since I was low on nitric and my sulfuric cell is no longer operational since I had to give back the power source. I borrowed it. Below is the picture of a few, and how they look right now. Well I put them in AP a few days ago with a bubbler and they ran for a day or two and nothing happened no color change in the acid. No dissolving a base metals. So I took that HCL out or I mean AP. And put some new AP in there maybe a 5:1 ratio. Put it on heat still nothing happens. I asked a fellow refiner and he suggested perhaps putting it in a little bit of sulfuric acid a test run of about 10 pins. And then a few drops of nitric acid to see if the base metals would dissolve. Well here's another picture, a picture of a pin after doing said test. As well as what the liquid looks like now. It's white and milky with a bluish tint and most of the pins still have most of the base metals on it. Could you tell me what this white milky substance is? is it silver chloride? Also there is a screenshot of what the pins came from. It's just a screenshot of some pins that someone is selling on ebay. But they look just like the pens I have but still in the plastic. And their plastic is clear whereas mine was white. Any helpful advice would be appreciated I only did those 10 pins as a test run and it doesn't look like sulfuric acid and nitric acid it's going to be the answer.
Partially plated pins won't disolve
- Thread starter Rreyes097
- Start date
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Cupric chloride will not attack gold ( unless a strong oxidizer is added), if the gold plating is thick the solution may not be able to contact the copper or base metals under the gold.
you can try cutting the pins into small pieces, or use oxidizer to attack the gold.
you can try cutting the pins into small pieces, or use oxidizer to attack the gold.
What kind of oxidizer? What's a good one? Because hydrogen peroxide want strong enough. Also it is only half plated with gold. Shouldn't the acids be able to get to base metals via the unplated portion?
If those are wire wrap pins you should be able to attack base metal without using a strong oxidizer, if you have free HCl in a concentrated enough solution with air bubbled into solution forming cupric chloride CuCl2 to attack the copper and other base metals, if too dilute and not acidic enough the green solution would look blue with white salts of cuprous chloride CuCl...
Copper will not dissolve in HCl unless an oxidizer is involved.
Gold will not dissolve in HCl unless an oxidizer is involved.
Air is a strong enough oxidizer (bubbled into the acidic solution) will dissolve copper, but is not a strong enough oxidizer to effectively attack gold, 3% hydrogen peroxide is slightly stronger oxidizer than bubbling in air, and can be used to attack copper with limited attack to gold.
If you cannot dissolve copper in your acid you may not have enough dissolve oxygen in solution, or the acid is used up making salts, cold temperatures will hold more gases such as oxygen, but cold acids may not attack metal as fast as a warmer acid (two side of the same sword).
My eyesight is failing those look like wire wrap pins, if you included wire you may possibly have tin, lead or other metals involved thus the white salts.
if very dilute maybe you converted your cupric chloride CuCl2 into cuprous chloride CuCl which would not attack copper (also a white powder or salt of copper).
To dissolve gold we need a stronger oxidizer.
30% H2O2 and HCl acid will attack gold.
Nitric acid and HCl acid will attack gold.
Chlorine gas and HCl acid will attack gold,
sodium hypochlorite (bleach) and HCl acid will attack gold
Most any chemical that converts HCl acid or forms chlorine gas in solution will also attack gold.
Other strong oxidizers like perchlorate or MnO2...
Copper will not dissolve in HCl unless an oxidizer is involved.
Gold will not dissolve in HCl unless an oxidizer is involved.
Air is a strong enough oxidizer (bubbled into the acidic solution) will dissolve copper, but is not a strong enough oxidizer to effectively attack gold, 3% hydrogen peroxide is slightly stronger oxidizer than bubbling in air, and can be used to attack copper with limited attack to gold.
If you cannot dissolve copper in your acid you may not have enough dissolve oxygen in solution, or the acid is used up making salts, cold temperatures will hold more gases such as oxygen, but cold acids may not attack metal as fast as a warmer acid (two side of the same sword).
My eyesight is failing those look like wire wrap pins, if you included wire you may possibly have tin, lead or other metals involved thus the white salts.
if very dilute maybe you converted your cupric chloride CuCl2 into cuprous chloride CuCl which would not attack copper (also a white powder or salt of copper).
To dissolve gold we need a stronger oxidizer.
30% H2O2 and HCl acid will attack gold.
Nitric acid and HCl acid will attack gold.
Chlorine gas and HCl acid will attack gold,
sodium hypochlorite (bleach) and HCl acid will attack gold
Most any chemical that converts HCl acid or forms chlorine gas in solution will also attack gold.
Other strong oxidizers like perchlorate or MnO2...
I have tried HCl and peroxide and air twice with fresh solutions. I was thinking nitric and distilled water. The pins are clean no wire and no solder or tin visible. So I don't know what to do.
Ohiogoldfever
Well-known member
- Joined
- Nov 8, 2020
- Messages
- 254
I use AP on a regular basis. By my estimation you’re just in to big a hurry. Cut a few pins to open up to the copper, or even add in a little Old AP if you have any. Toss em in there and stir them ever few days.
I find with AP being in any hurry works against you.
I find with AP being in any hurry works against you.
Martijn
Well-known member
I have done those 19" rack ESD controller pins in AP. You can pop them open with some prying, leaving the internal plated parts to be shaken out. The way you have cut them from the socket, you should have enough copper exposed for AP. Even without cutting them I dissolved fully plated pins in AP, just need some patience. Mine took 2 months last time.
With this type you will have to get the plastic part open to get the pins out, AP will eat away base metals leaving gold foils inside the sockets. A pain to get them out.
And may I advise wearing gloves when holding beakers with toxic chemicals in it, especially when posting pictures (on this site) ?
We prefer pictures of good practice. It's not lemonade and cookies we're working with here. You can take one off to operate the camera. Many people can see your post, and do not realize the risks, like most You-Tube video's. Monkey see, monkey do, monkey gets some health issues.
With this type you will have to get the plastic part open to get the pins out, AP will eat away base metals leaving gold foils inside the sockets. A pain to get them out.
And may I advise wearing gloves when holding beakers with toxic chemicals in it, especially when posting pictures (on this site) ?
We prefer pictures of good practice. It's not lemonade and cookies we're working with here. You can take one off to operate the camera. Many people can see your post, and do not realize the risks, like most You-Tube video's. Monkey see, monkey do, monkey gets some health issues.
kurtak
Well-known member
Ohiogoldfever said:
What Ohiogoldfever said --- You are just in a big hurry
The AP process is a VERY SLOW process & as I understand it can take weeks (like a month or more) to dissolve something like copper/brass pins
I have never used the AP process for that very reason --- I always used nitric - done in a day --- but then I got my nitric VERY CHEAP
Kurt
kurtak
Well-known member
Martijn said:
What Martijn said
That will get the job done in a day --- but if you are paying more the $7 per gallon for the nitric it will likely cost more then the gold is worth --- which is why most members use the VERY SLOW AP process
Kurt
I had them in AP for at least 3 days with no reaction whatsoever. But I guess I'll try it again or nitric and water I don't know Also I apologize for the lack of gloves in the picture I swear I usually wear gloves it was just a spur of the moment shot I wanted to try to get a picture of the bottom of the beaker. So I guess I can wait and put them in AP longer than the three days I tried already.
Three days May not be long enough. I have had batches of pins in AP for several weeks, with bubbler, before any noticeable reaction. Some material takes a lot of time.
Just an observation, but you seem to be in a hurry at times. Patience is truly a virtue in this business. No everything can be done in a day, a week, or even a month. Slow down. Take notes. Learn from others.
Time for more coffee.
Just an observation, but you seem to be in a hurry at times. Patience is truly a virtue in this business. No everything can be done in a day, a week, or even a month. Slow down. Take notes. Learn from others.
Time for more coffee.
Martijn
Well-known member
When did your solution start to show white residue? After the nitric addittion?
Then it will likely be tin paste from the bronze base metal (copper + tin) therefore nitric not will give the desired result with bronze pins imo. You'll have foils in tin paste to process. Incineration and HCL leach to get that tin out.
I did not find any silver in this type of pins. It's gold on nickel on a spingy type of bronze core.
If the white stuff dissolves in HCL and turns green, then it most likely is copper 1 chloride. The formation of that indicates a weak AP and HCL addittions are needed. You will have to add HCL several times to completely dissolve all base metals. So keep some room in the bucket. And suspend the pins from the bottom by hanging them in a perforated bucket. And you can shake and rinse a bit that way. Air bubbler underneath.
I made my perforated basket from a big plastic jar with a hot needle on a piece of wood to poke the holes. Just big enough to flush foils through.
No need to replace AP. It's the copper 2 chloride that does the job, not the HCL. As long as there is some free HCL to turn it back into copper 2 chloride. The formation of the insoluble white stuff is a sign that more copper is going into solution than the air and HCL can convert, if the pins get covered by it, the acid can no longer reach the pins and reaction stops until all CuCl1is dissolved again.
Martijn.
Edited to change brass into bronze.
Then it will likely be tin paste from the bronze base metal (copper + tin) therefore nitric not will give the desired result with bronze pins imo. You'll have foils in tin paste to process. Incineration and HCL leach to get that tin out.
I did not find any silver in this type of pins. It's gold on nickel on a spingy type of bronze core.
If the white stuff dissolves in HCL and turns green, then it most likely is copper 1 chloride. The formation of that indicates a weak AP and HCL addittions are needed. You will have to add HCL several times to completely dissolve all base metals. So keep some room in the bucket. And suspend the pins from the bottom by hanging them in a perforated bucket. And you can shake and rinse a bit that way. Air bubbler underneath.
I made my perforated basket from a big plastic jar with a hot needle on a piece of wood to poke the holes. Just big enough to flush foils through.
No need to replace AP. It's the copper 2 chloride that does the job, not the HCL. As long as there is some free HCL to turn it back into copper 2 chloride. The formation of the insoluble white stuff is a sign that more copper is going into solution than the air and HCL can convert, if the pins get covered by it, the acid can no longer reach the pins and reaction stops until all CuCl1is dissolved again.
Martijn.
Edited to change brass into bronze.
Brass is an alloy of copper and zinc. Bronze is an alloy of copper, tin, and sometimes other elements.
Dave
Dave
A question for those who have knowledge of electronic component manufacturing processes:
Do the makers of these thinly plated pins/components ever top-coat the exposed parts with any type of clear-coat to aid against wear and tear abrasion? Or would that have too much of an effect on electrical function?
It is also possible that oils from your fingers are transmitting to the pins during dissembling. Why not use a handheld butane mini-torch that jewelers use and fan a bushy flame over the pins before refining and burn off any contamination before the AP process?
An example - many more can be found on Amazon.
Peace and health,
James
Do the makers of these thinly plated pins/components ever top-coat the exposed parts with any type of clear-coat to aid against wear and tear abrasion? Or would that have too much of an effect on electrical function?
It is also possible that oils from your fingers are transmitting to the pins during dissembling. Why not use a handheld butane mini-torch that jewelers use and fan a bushy flame over the pins before refining and burn off any contamination before the AP process?
An example - many more can be found on Amazon.
Peace and health,
James
Martijn
Well-known member
I realized it just after i wrote it and edited. :lol:
But yes, i encountered a lot of tin paste back when i made my first attempt and mistakes when starting this journey. Pins in nitric. So i assumed its bonze. Or a tin plating layer.
Thinking back, there may have been some solder in the mix, so there goes the assumption it's bonze. :?:
I think i read it somewhere too.
But yes, i encountered a lot of tin paste back when i made my first attempt and mistakes when starting this journey. Pins in nitric. So i assumed its bonze. Or a tin plating layer.
Thinking back, there may have been some solder in the mix, so there goes the assumption it's bonze. :?:
I think i read it somewhere too.
Martijn
Well-known member
cosmetal said:
I dont think so. If there was a conductive wear resistant coating out there, why bother plating with gold?
Heavy duty parts get thicker plating.
Good point - but what about potential contamination by body oils?
James
James
Martijn
Well-known member
Burn them off!
I see sreetips do it to all his jewelry and clean scrap every time. So yes. Good idea.
I see sreetips do it to all his jewelry and clean scrap every time. So yes. Good idea.
I thought I just posted reply is it not there?
Martijn
Well-known member
No.
