How to get black from sterling and gold

Jewelry Discussion
1

I was told that every persons jewelry turned black, because someone put the wrong chemical in the swimming pool. I am told it was rock salt ???. and all jewelry turned black and cannot get the black out. Any ideas,

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I’ve had the same problem with some argentium jewelry in a regular swimming pool - not a saline pool as have become very common. I tried pickling it with no improvement. Polishing cloth did nothing. The only way I could get it shiny again was with the buffing wheel and compound.

3

This might be too simplistic, but silver chloride is black. Could it be possible that over-chlorinating the pool, or using the wrong source of Cl was responsible? If it’s silver chloride, placing in an electrolysis tank and connecting the positive terminal to the silver might drive the chloride away. Might look up “how to make a silver/silver chloride electrode” and do the reverse.

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Thank you

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Thank You

6

For 30 years I have warned people about getting their silver in any medium containing chlorine. I have told them it would blacken their silver and it would require machine polishing to get it back to an original appearance. Stay out of hot tubs and swimming pools while wearing jewelry. Unsoftened water with a high Sulphur content appeared to create similar problems.

I tried a number of methods short of machine polishing before I gave into the inevitable and re-polished bracelets for people. I refuse to use Tarn-x so I don’t know if that would work and I try to run an acid free shop so I have never tried bright dipping on chlorine damaged silver. Maybe that would work, I just don’t know.

But I find an ounce of protection…

Don Meixner

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7

Are you sure this referred to gold as well as silver jewelry??

Janet in Jerusalem

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So they say,

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So… if this creates such a tenacious blackening of silver, is it something that could potentially be used to intentionally create a black finish? Does it have any detrimental side effects other than the color? Having tried a few different patination methods and been less than 100% satisfied with any of them especially for getting BLACK black, this is piqueing my interest.

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10

I was wondering the same thing! Any thoughts on this?

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11

I might just try it on a small sample and leave it hanging on my bench for six months, see what happens. I found some black marks on my ring the other day that won’t come off with a regular polishing cloth and realized I’d been handling some chlorine bleach, so I’ll probably start with that. I definitely wouldn’t sell anything until someone with a stronger chemistry/smithing background than mine confirms, but… it’s worth a scrap to see!

ETA: I googled and found a description saying that the reaction of the bleach with the silver can potentially cause pitting or etching of the surface, so that’s definitely something to be careful of. What I’m wondering is if using a quick dip or brushing the bleach on and then immediately washing it off as soon as the color turns would prevent the pitting.

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My first instinct would be to say yes, a quick but deep rinse would prevent pitting. For some applications, electrolysis could be used to apply the chloride, but might require masking the parts you want to keep unblackened. Now I’m really curious, going to look up more and report back.

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Thanks

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The chemistry of bleach is a bit complicated, as different reactions take place within the ingredients of bleach solutions on their own. This statement is meant to address the possibility of pitting, which seems unlikely but what do I know. However, a Google search indicates that a popular method for coating silver with silver chloride for electrodes is precisely submerging it in undiluted bleach for up to 20 minutes followed by rinsing. The electrodes are said to be very long-lasting, so it’s worth a try for jewelry. The other method is electrolysis in salt (0.9% NaCl, specifically) with the piece as the positive electrode, but I imagine that the geometry of the item could result in uneven deposition of the chloride. A low current yields more uniform coatings, and turning the item during the process is probably a good idea, as in other types of electroplating. A quick reference is found here: Chloriding Ag/AgCl Electrodes Disk, Pellet, or Wire Hope the link works! The final issue would be to determine for sure how durable the coating is under normal wear. BTW a few posts ago I wrongly suggested how to get rid of the chloride through electrolysis: I had the polarity backwards.

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Thanks