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"Finishing Technology Hotline BBS" Postings by Topic

Ed. note: before the internet existed, there was a time when "Sysops" (system operators) ran publics forums via dial-up modems and "BBS" (Bulletin Board System) software. Here is one such discussion from 1991.


Algae Growth in Gold Plating Rinses



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Msg. #2330 in **Ask Plater B**
Posted on 12/31/91 at 09:32:09
To: ALL From: ANONYMOUS CALLER

- BACTERIA/ALGAE IN STAGNANT GOLD RINSE

I HAVE A FRIEND (THE MOST FAMOUS CLICHE!) WHO HAS A PROBLEM WITH BACTERIA GROWING IN HIS STAGNANT GOLD RINSE. IS THERE A COMMONLY USED BACTERIA
- ALGICIDE? I CAN FIND OUT MORE ABOUT THE DETAILS OF THE PROBLEM IF SOMEONE HAS SPECIFIC QUESTIONS.



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Msg. #2332 in **Ask Plater B**
Posted on 12/31/91 at 21:48:04
To: ANONYMOUS CALLER From: TED MOONEY

- Reply To 'BACTERIA/ALGAE IN STAGNANT GOLD RINSE'

I've heard of only two effective algacides/bacteriacides, although there may well be others. One is bleach (sodium hypochlorite or calcium hypochlorite), the other is ultraviolet light. Usually in a rinse tank the contents are just dumped, then the tank walls washed with bleach. This would be a safe procedure for a cyanide gold, but not perhaps an acid gold since chlorine gas would be released. I also don't know the value of the gold in the rinse, and whether it can be thrown away. You could take a sample to the lab and see if the algae is filterable, such that you could pass the rinse through to a clean container, wash up, then return it. I don't know much about the ultraviolet approach except that it is commonly used for high purity deionized water. A manufacturer could advise you of the applicability. As a wild shot you could try peroxide or one of those "Neutra-lizer" ozone generators. Anybody with more direct hands-on than me, please chime right in.



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Msg. #2346 in **Ask Plater B**
Posted on 01/05/92 at 01:09:45
To: ANONYMOUS CALLER From: JOHN LOVIE

- Reply To 'BACTERIA/ALGAE IN STAGNANT GOLD RINSE'

Most gold baths, particularly the acid variety, are excellent algae food when diluted as in a stagnant rinse. The best solution is to replace the rinse frequently, but this is a problem if you're trying to build up the gold content for more efficient recovery. Tricks I've tried are adding a little extra free cyanide to the rinse, adjusting the pH up to 9 or higher, adding some copper to the rinse tank. I never did find a good fungicide when I was with SEL-REX, but now I've found a possible source
- tropical fish or aquarium stores. They sell a material for removing all traces of algae from a fish tank. Sounds like it might be worth a try. Don't remember the name, but they all have it. Let me know if it works. Cheers John Lovie



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Msg. #2359 in **Ask Plater B**
Posted on 01/12/92 at 21:39:41
To: TED MOONEY From: KEN ROSENBLUM

- Reply To 'BACTERIA/ALGAE IN STAGNANT GOLD RINSE'

WE HAD A PROBLEM WITH ORGANIC GROWTH IN A GOLD RINSE ONCE, BUT IT LOOKED MORE LIKE A FUNGAL GROWTH THAN BACTERIAL. AFTER FINDING VIA AA SPECTROPHOTOMETRY THAT THE GOLD IN THE RINSE WAS WORTH ABOUT $3.00, WE DUMPED THE RINSE AND MADE UP A NEW ONE WITH CLEAN WATER.



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Msg. #2372 in **Ask Plater B**
Posted on 01/15/92 at 16:33:43
To: KEN ROSENBLUM From: JOHN LOVIE

- Reply To 'BACTERIA/ALGAE IN STAGNANT GOLD RINSE'

Most of the problems I ran into were fungal. They also tended to happen at certain times of year when the spore count was high.



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Msg. #2399 in **Ask Plater B**
Posted on 01/28/92 at 10:39:50
To: ED KUDRAK From: JOHN LOVIE

- Reply To 'BACTERIA/ALGAE IN STAGNANT GOLD RINSE'

I've had luck with potassium permanganate, also with formaldehyde (although I almost had to produce a degree certificate to get the pharmacist to sell it to me!) The other materials we have used are a solution of copper sulfate and potassium chromate (1 tsp to 10gal of a 1.28% CuSO4 and an unspecified amount of K2CrO4). This one's for fungus. A full of antibiotics such as tetracycline and erythromycin is also available over the counter at reasonable prices at aquarium stores! Silver is a well known antibacterial
- silver nitrate should work well. One thing it doesn't stop unfortunately is mold
- I've lost a number of photographic slides that way. Do I recall a fungicide from Givaudan? I seem to remember having to order some from Nutley when I was working in Holland. Givgard? Cheers John


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