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View Full Version : Ascorbic Acid to dissolve silver off film..



Athiril
10-28-2009, 06:01 AM
Okay so I made up a strong solution of ascorbic acid with pleny of sodium hydroxide, much stronger in each case then one would use for development, gathering up so of my many failed processing attempts and dumping them in the jar the silver developers and eventually is removed from the film.

Until I'm left with clear acetate/base, a very dark grey opaque solution.

Running it through a paper filter, barely any of the solution gets caught in the filter, so it is dissolved.

Im assuming if I evaporated the solution and use enough methylated spirits to redissolve the ascorbic acid, I can filter that off to remove the ascorbic acid, then redissolve in water, in which the silver shouldnt be able to dissolve without the ascorbic acid.. at least I think.


What form is the silver in the solution?


I want to experiment with this until I get my next order of chemicals in which will include bromide and nitric acid.


putting a little does clear a dark potassium permanganate solution clearer, and sort of a yellow dull colour, so im guessing its still metallic silver.. back to halides in the permanganate... i wonder if this can be of use to me

Photo Engineer
10-28-2009, 08:07 AM
Sodium Hydroxide alone will remove the coated layer from film.

It will also remove the subbing in most cases, thereby rendering the film uncoatable in the future. It depends on the subbing.

PE

Athiril
10-28-2009, 08:29 AM
Ah I was going to ask about recycling the film base... so much to learn..

Guess I cant do much until I get the rest of the stuff I need.


Edit:

Im getting a precipitation from a small amount of solution (0.5ml) in a copper sulphate solution... also in magnesium sulphate solution (epsom salts).

totalamateur
10-28-2009, 10:04 AM
Is an NaOH / Ascorbic acid solution what is normally used to remove exposed silver from a negative in order to make a positive (i.e. the exposed negative is clearedof all silver, the remaining unexposed halides exposed to light and redeveloped to form a positive?)

I was considering shooting paper negatives and processing them directly into positives, but couldn't find the process.

Photo Engineer
10-28-2009, 10:53 AM
The Sodium Hydroxide alone will remove all emulsion and silver from a negative and may remove all or some of some types of subbing. It has nothing to do with making positive or negative images. And, it is a rather poor way of removing the coating. Much like using a nuclear weapon to kill gnats! Over kill!

Basically (pun intended) the NaOH causes complete decomposition of gelatin which then dissolves into the solution as a mix of the salts of the various amino acids making up the gelatin.

PE

Kirk Keyes
10-28-2009, 02:56 PM
This all sounds like a way to make a big mess...

Is the point of this to recover silver metal or just to have some fun? Or perhaps both?

tiberiustibz
10-28-2009, 03:39 PM
It's used to clean drains. The fact that it removes emulsion from film is secondary :D

Kirk Keyes
10-28-2009, 07:01 PM
Ascorbic Acid for drains??

Photo Engineer
10-28-2009, 07:05 PM
NaOH is for drains and for removing emulsion from film, paper and plates. Ascorbic acid is riding along doing nothing much AFAIK. NaOH can remove skin from bones and dissolve clothes as well.

PE

sanking
10-28-2009, 10:56 PM
NaOH is for drains and for removing emulsion from film, paper and plates. Ascorbic acid is riding along doing nothing much AFAIK. NaOH can remove skin from bones and dissolve clothes as well.

PE

So what is the stuff that mobsters use for dissolving skin, bone and all? I gather NaOH won't do that?

I recall seeing a scene on the Sopranos where they chopped up a body into parts and then placed the parts in the stew that apparently reduced them to nothing.

Sandy

Athiril
10-29-2009, 12:53 AM
Is an NaOH / Ascorbic acid solution what is normally used to remove exposed silver from a negative in order to make a positive (i.e. the exposed negative is clearedof all silver, the remaining unexposed halides exposed to light and redeveloped to form a positive?)

I was considering shooting paper negatives and processing them directly into positives, but couldn't find the process.

Its a developer solution, just not in this strength normally.

I assume you could just copy the b&w reversal process paper, but with whatever you develop paper with normally to your taste and a weaker version of the bleach.

I would recommend not using dichromate bleaches, as dichromate according to it's MSDS is a confirmed carcinogen for humans as well as mutagenic, while permanganate is listed as being only mutagenic on bacteria and yeast only.


This all sounds like a way to make a big mess...

Is the point of this to recover silver metal or just to have some fun? Or perhaps both?

It's rather an interesting looking mess, especially the settled copper sulphate-precipitate solution :)


http://i37.tinypic.com/i1lle0.jpg
http://i34.tinypic.com/2mmwy9l.jpg

Photo Engineer
10-29-2009, 08:50 AM
Oh, Sandy, what thoughts you are projecting here. :(

Now we know your darker side.

Anyhow, to my knowledge only HydroFluoric Acid will totally reduce a human (or any) body to nothing but liquid and gas. You have to do it in a special container though or it eats the container. I believe that a ceramic bathtub was the container of choice. Sodium Hydroxide comes next. And, the nice thing about NaOH is that it, like HF, dissolves most clothing as well.

You can rest easy now, knowing this.

PE

hrst
10-29-2009, 11:55 AM
But Mr. PE, how do you know all this??

Scary! :D

Kirk Keyes
10-29-2009, 12:30 PM
It's rather an interesting looking mess, especially the settled copper sulphate-precipitate solution :)
http://i34.tinypic.com/2mmwy9l.jpg

That looks like some of the "science" experiments I used to make as a teenager. Thanks for sharing the photos!

Kirk Keyes
10-29-2009, 12:45 PM
Anyhow, to my knowledge only HydroFluoric Acid will totally reduce a human (or any) body to nothing but liquid and gas.

I think you will find there will be a lot of calcium solids from the bones left after hydrofluoric acid gets done.

There was a Dateline NBC murder story the other day where some lady that owned a lab had disposed of someone in a barrel of aqua regia (nitric + hydrochloric acids), but there were still some chunks left that they got DNA out of. The person had only been in there for a month.

A lot of sulfuric would probably digest someone, but there would again be some solids (calcium sulfate). The sulfuric would dehydrate it, then char it, and all the organics would eventually turn in to a black, oily goo.

Photo Engineer
10-29-2009, 01:17 PM
Ahh, I would just flush the CaF2 slurry down the drain. ;) That is what it would be.

PE