Invisible to Visible Silver Gelatin Prints

Keo · May 7, 2017

Hello folks. I've been a lurker on these forums for quite some time and wanted to make a thread to possibly pick some minds. I seem to remember looking through the forums about a process that allowed a print to appear in light and vanish in darkness. I briefly remember reading the chemical's name as well as the poster stating that it was (insert photographer's name here) way to do a party trick. I'm interested in trying to either find the resources or get new information in regards to if this process is an actual, valid, thing.

Thanks in advanced and stay awesome.

Keo

AgX · May 7, 2017

Welcome to Apug!

Everything I look at vanishes when in darkness...

Kevin Caulfield · May 7, 2017

I think it's the other way around. I think it was done here in a postcard or print exchange.

Molli · May 7, 2017

If you make a print as normal then bleach it back using a rehalogenating bleach (Potassium Bromide + Potassium Ferricyanide + Water) the image will be pretty much invisible. You can then re-develop it in daylight (I'd avoid direct, bright outdoor sunlight rather than risk solarising the print) but shade or indoors is perfectly fine. Hey presto! Invisible to visible print right before your audience's eyes

Keo · May 7, 2017

I do appreciate the humor, however it was not something like a bleach and redevelopment. Well I mean if I remember correctly it involved a similar process to it, replacing some part of of the silver halide with another metal, salt, etc. I found a small spark note I wrote down in my journal but I did not write the thread title down, >.<. The print as I wrote down is treated with X chemical or process, when dry and exposed to light the image would be visible. However, the print would fade overnight.

I've briefly looked into the Photochromic principles that are used for transition lenses. The closest thing I've come to figuring out how those work is that a silver halide and copper chloride is combined with molten, optical, glass. These two chemicals work together in the glass, silver halide darkening the lens in UV and copper bleaching it when light is removed. I'm not a chemist and would have no idea how to approach this with a silver gelatin print. However, I figure it would be possible since both chemicals described in the photochromic lenses are the same as what is used in the Darkroom processes.

Thanks again.

Keo

Old-N-Feeble · May 7, 2017

To make prints permanently invisible, you must destroy Sol.

Keo · May 7, 2017

Thanks again for humoring my post. However, I've found that I was looking in the wrong avenue. I found what I was looking for in the old altphotolist. Thanks again.

AgX · May 7, 2017

It seemed that you got deterred. However it seems that so far we could not begin something with your request.

removed account4 · May 7, 2017

Keo said:
Thanks again for humoring my post. However, I've found that I was looking in the wrong avenue. I found what I was looking for in the old altphotolist. Thanks again.

so ... what was it ? you can't leave is all hanging like this
was it called too much to drink ?

BrianShaw · May 7, 2017

Hi Keo. I do hope that you'll share the information with us. I am completely unknowing of what you described but very interested.

Keo · May 7, 2017

Oh, sorry. Yeah, it was a brief mentioning of using Potassium Iodide to bleach a print, not wash the print, and let it dry fully. This is just anecdotal knowledge, by apparently when the bleached print is exposed to light the image will become visible again. When not in light it'll return to whatever color the bleach made the silver into. That is what I've gathered so far, however the cost of potassium iodide is a little too much for me personally to continue looking into it. I say this of course with a cart full of chemicals from Photographer's Formulary. However, it is now noted in my journal for future experiments.

Andrew O'Neill · May 8, 2017

That is the most interesting/bizarre thing I've heard. That would be neat to see.

Molli · May 8, 2017

Great, now I'm going to have to invest in some Potassium Iodide to see for myself. Who knew chemicals could be addictive?

Oh, wait....

Thanks for letting us know the results of your search, Keo. I've got some kids floating around somewhere who would completely trip out in seeing that! Actually, as a big kid, I'd be pretty happy to see that myself.

Keo · May 8, 2017

Molli said:
Thanks for letting us know the results of your search, Keo. I've got some kids floating around somewhere who would completely trip out in seeing that! Actually, as a big kid, I'd be pretty happy to see that myself.

I would feel like a kid in a candy shop if this is an actual thing. Though considering if it does work, I'm certain it wouldn't be an infinite process. Since it is a bleach without a fixation I'd imagine the reaction would either be a one and done sort of affair or at least good for a couple cycles. Blegh, now I really want to do it, I just found out that I got one half of the equation to make my own potassium iodide at home. I'll keep the thread up to date with what I find out.

Nodda Duma · May 8, 2017

Potassium Iodide pure enough for photography purposes is about $0.15 or less per gram on ebay.

pdeeh · May 8, 2017

I've got a 100g jar of KI photo grade.
Now where's my box of scrap prints?

nmp · May 8, 2017

Keo said:
Oh, sorry. Yeah, it was a brief mentioning of using Potassium Iodide to bleach a print, not wash the print, and let it dry fully. This is just anecdotal knowledge, by apparently when the bleached print is exposed to light the image will become visible again. When not in light it'll return to whatever color the bleach made the silver into. That is what I've gathered so far, however the cost of potassium iodide is a little too much for me personally to continue looking into it. I say this of course with a cart full of chemicals from Photographer's Formulary. However, it is now noted in my journal for future experiments.

Keo, Hi:

Wouldn't you need something like potassium ferricyanide to first form the silver ferrocyanide which then will react with the KI to give you AgI and the accompanying bleaching. Once the print is bleached and the image has disappeared, the photosensitive AgI can get back to Ag when exposed to light, but this being a DOP, it would be most certainly will have to be "re-developed" to get the full dark image. Finally, once the image is back, unless the all reactions have been retraced and ferricyanide regenerated, how will the second (dark storage) bleaching occur, particularly in the solid state, is a good question. Excess ferricyanide in the first step?

In principle though, shouldn't NaCl work also (may be not as well) if procuring KI is a problem.

Still not clear to me how this now-you-see and now-you-don't trick will all go down...

:Niranjan.

Nodda Duma · May 8, 2017

I could be wrong but I *think* the OP is attempting to create a photochromic compound, which is fundamental to how photochromic eyeglasses (aka transition lenses) work.

pdeeh · May 8, 2017

BINGBONG
Paging Mr. Mowrey, paging Mr. Mowrey.
Mr. Mowrey to AltProcess Forum Please.

NedL · May 8, 2017

Keo · May 8, 2017

Nodda, that is the ideal effect I'd love to achieve. I'm sure others would as well! Doing a big bulk buy of a lot of stuff in about a month. Saving them pennies while paying down debts and all hahaha.

Nodda Duma · May 8, 2017

Good luck and keep us posted

Photo Engineer · May 9, 2017

I know nothing about this process. I do know of a color process which was invisible to regular visible light but became a full color image under UV illumination.

PE

MrBrowning · May 9, 2017

Keo can you provide a link. I'd like to give it a shot too.

OptiKen · May 9, 2017

Molli said:
Great, now I'm going to have to invest in some Potassium Iodide to see for myself. Who knew chemicals could be addictive?

Oh, wait....

lol

Invisible to Visible Silver Gelatin Prints

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