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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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23rd Jan 2020, 7:14 pm | #21 |
Hexode
Join Date: Feb 2014
Location: Southampton, Hampshire, UK.
Posts: 419
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Re: Black oxide coating on brass
I dont think Lead Acetate is a good way forward I used to work with the stuff in gas detectors and can only re iterate wikipedias toxicity warning.
However I have just spent some time cleaning off some brass that had gone black due to leaking alkaline batteries - more nasty stuff but it certainly left a very hard to remove black coating on the brass parts. Pete |
23rd Jan 2020, 10:58 pm | #22 | |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,711
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Re: Black oxide coating on brass
Quote:
I tried to photograph this difference in emissivity without success.
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-- Graham. G3ZVT |
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23rd Jan 2020, 11:37 pm | #23 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,337
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Re: Black oxide coating on brass
When I used to do my own black and white photography, I found that spillage of exhausted fixer would silver plate the pennies I used to use under the fixer dishes to level them up. The plating was initially black, but would readily buff up shiny using a cloth. I found it worked on the brass door knobs of our prefects' room. If
left the silver plating would soon blacken. Finding someone who still uses traditional processing that used fixer could be cadged from might be less difficult than trying to source toxic chemicals. The fixer should ideally be as exhausted as possible: fresh fixer contains no silver. |
26th Jan 2020, 6:48 pm | #24 | |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,711
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Re: Black oxide coating on brass
Quote:
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29th Jan 2020, 11:45 am | #25 | |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
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Re: Black oxide coating on brass
Quote:
I'd need to develop a fair few films to acquire enough silver to blacken the gongs on my bellset No: 20 though.
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Regds, Russell W. B. G4YLI. |
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29th Jan 2020, 1:40 pm | #26 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,337
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Re: Black oxide coating on brass
I used to use M&B Amfix, which fixed in 2 mins, as the 10 min time of ordinary fixer was the bottleneck in processing prints. I normally used to do well over 100 prints in a session. I actually read the leaflet that came with it, and noted they recommended the two bath approach, where you kept separate A and B solutions. 2 mins in A, followed by 2 mins in B. This meant that if A became exhausted during a session, B would complete the fixing. When A tested as exhausted (by failing to clear a scrap of undeveloped 35mm leader), A was discarded (or put aside for plating), B became A, and a fresh solution was made up for the new B. This ensured that the maximum life was squeezed out of the relatively expensive Amfix (which I used to buy in half gallon bottles for economy) and ensured that I never had any problems with prints deteriorating due to incomplete fixing. It also meant that my exhausted fixer was absolutely saturated with silver.
Last edited by emeritus; 29th Jan 2020 at 1:49 pm. |
29th Jan 2020, 3:02 pm | #27 | |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
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Re: Black oxide coating on brass
Quote:
I used to use Paterson Acufix (An Accufix is a LORAN receiver made by Megapulse, which is probably why it tripped off the fingers so readily!) when we had a works 'club' darkroom back in the early '90s and I used to print there.
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Regds, Russell W. B. G4YLI. |
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