# Why is light & AgCl a problem?



## kurt (May 1, 2011)

Ok – about a month ago when working on my first attempt at silver (using the salt/lye/sugar method) I suspected I had some lead chloride in my AgCl due to my source (electrical contact points) so posted a question titled “White Stuff in my Silver Oxide” & it was suggested that I expose the AgCl to sun light to determine if lead was present as the AgCl would turn purple & the lead would stay white & if there was lead I could then remove it by washing with hot water.

I am now using the copper cement method – but – being new at all of this I am still making “small” amounts of AgCl running test tube size experiment on different things I read as part of my learning process.

The AgCl from each of these experiments I dump into a small jar & although not exposed to direct light when set aside – it has been exposed to low level light & over time has developed the resulting purple color

Now – I have recently read that when working with AgCl it should be done in low level light or red light conditions because light exposure is a problem. – So – other then light exposure turning the AgCl purple – what is the problem with light exposure - & - if you have AgCl that has been exposed (purple AgCl) how do you deal with it???

Kurt


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## butcher (May 1, 2011)

Kurt, light will convert silver chloride to elemental silver and chlorine, adding HCl will make purple silver back into AgCl white powder,

I feel you may have misunderstood the person who told you to put in sun, He was probably just telling you that AgCl will turn purple in light and PbCl will not,(so you could see the difference in them), there is no need to have in light, boiling hot water will make lead chloride soluble to wash it from silver chloride, remember silver chloride will need time to settle, for separation.

GSP has advised several time's to keep light out of the picture with silver chloride, I do mine outside for the most part and have not worried about the light that much.

Maybe we can get Chris to comment on the effects and problems with working with silver halides in the light.


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## Harold_V (May 2, 2011)

I, too, never worried about light exposure to my (small amount) of silver chloride. I kept a half gallon jar on my bench at all times, in which I stored traces of silver chloride. When it got about half full, it was well washed with hot water, then converted to elemental silver with aluminum and HCl. By the time it was converted it was generally somewhat purple in color. I used fluorescent lighting in my lab. Didn't seem to make any difference--in the end I had silver. Unless Chris has something earth shattering to reveal, I expect that it doesn't make much difference if you let it see light. 

Harold


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## kurt (May 2, 2011)

Thanks for the info guys - & more important – thanks for providing &/or being part of this forum. I used to live in Northern California & when living there was involved in both placer mining & hard rock mining. A little over a year ago I ran across an article in a magazine titled “Urban Gold Mining” that was about recovering the PM’s from computers. 

Until I ran across this site a few months ago I was working off the HUGE amounts of miss info &/or incomplete info out there on the web. – For the most part I have just been collecting & tearing down electronics – selling the copper, aluminum & tin (I do a lot of other scraping to) & have just been playing with small batch experiments on the recovery/refining of the PMs.

At this point a have a “huge” pile of boards (close to a ton – both green & brown) & recently striped about 500 lb of the green boards & I have a inexpensive source for acid ($11/gal for nitric & $3.50/gal for HCL) --- I try to do as much research & experimenting as possible before asking questions so that I don’t burden the forum with a lot repetitive Q&A

This is all “way” more involved then it sounded when I first got into it – but the more involved I find it – the more it sparks my interest – so again – thanks for providing &/or being a part of this forum as I will certainly be needing more answers to questions & I hope I will be able to contribute to the forum with info & discoveries of my own along the way

Kurt


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