How to_BW Polaroid Emulsion

[AgX]

As a clarification:

That patent 2,352,014 is an US patent of André Rott. I gave his British patent 614,155. However this seems not to be accessible on the net.

 

[Photo Engineer]

I've been reading this over and find that one thing is missing......

SHUTDOWN!

You see, without shutdown, all processes keep going on and on and on. This is a crucial part of all instant imaging. No one has mentioned it at all.

If it does not take place, the final image is BLACK.

PE

 

[AgX]

Dear PE

This is one the very few times that I do not share your view.
I gave some hints that the development of the negative has to be stopped:

"The idea behind it is to produce a negative, dissolve the remaining halide…

The Polaroid technique added to this all the feature of instant development
(fast, chemicals in pods etc., later even self-controlled with SX-70).

After processing and forming of a positive image behind the screen by those migrated and developed halides, the second film is torn off.

As there is no parting of the layers it must be self-controlled."

Further more this thread is clearly directed at people who have some practical understanding of the common instant processes.


However the aspect how to save the positive image from being harmed by the remaining halide solvent, developing agent and alkali is even merely paid attention to in the literature I used. With positive exception of the Neblette.
The only advise feasible for home projects I could give besides washing, is to use resin coated paper for the receptive layer and think of an acid water based lacquer similar to the one used in some Polaroid processes.

 

[Photo Engineer]

Well, the overcoating brush used in Polaroid prints is a form of shutdown, but beyond that there can be a polymeric acid layer protected by a water repellanat layer. The base in the pod breaks down the repellant layer and is then further neutralized to the proper pH by the acid layer.

This is necessary in integral materials and sometimes optional in non-integral materials.

If you have a peel-apart material, the individual customer can be burned or harmed by the alkali or the other chemistry.

Without proper pH and removal of harmful chemicals, the image may 'tone' and turn brown or otherwise change in density.

This is why I bring it up.

PE

 

[AgX]

So again there was a misunderstanding...

I really thought you had i about the right timing between gaining the right negative density versus the right positive density.

Yes, the stability of the positive image should be an issue. Strange enough, in the most texts I've read this isn't an issue.
In one textbook, one that even gave a quite precise description of the process naming those metallic-nulei, stated that no further preservation would be necessary, but a lacquer coating to keep “ the silver image from mechanical damage”…

As even in the Neblette no principle compilation of the dangers to the image is given, could you give a basic explanation for the most simple case of substances remaining after instant halide diffusion process:

Silver grain (physically developed as that seems to influence its structure, grown on nucleus)
Nuclei (noble metal?, sulphide of heavy metal?)
Developing agent (Chinolate + benzochine)
Silver solvent (let’s say Na2S2O3)
Alkali
Recepting base (let’s say custom gelatinized on outfixed RC-paper)

This is different from a photo paper that has gone through a normal process but is not washed at all.

What kind of reactions would/could take place with the surrounding environment and between them?

 

[Photo Engineer]

I'm sure we are misunderstanding each other. The patents surely don't teach everything, nor do the texts. Having disassembleld the Polaroid products, and built them from scratch (in color) I understand the difficulties with this.

The silver image must be stabilzed against oxidation and sulfurization. A pyrazole compound among others lends its odor to the lacquer used. It also helps adjust pH.

In addition, the coating has timing layers and neutralization layers to prevent over development. The breakdown of the timing layer changes with respect to temperature, thereby mitigating any temperature effects. Otherwise, on a hot day the Polaroid print would overdevelop. Even so, they give times of development (lamination) for different ambient temps.

Kodak's Ektafllex peel apart print material had to have the same thing built into both the donor and reciever materials in order to get the right image quality and stability. So, it is needed for both B&W silver and color.

For more information, I refer you to patents by Barr, Bush and Thomas assigned to Kodak. Jack Thomas later became VP and Director of Research for Kodak. You may also want to look at patents by Henzel, and also by Armour and Mowrey.

PE

 

[z-man]

marhaba mustafa-asalamu alekum

the original research land did for his first patents was done here in nyc at the main public library on 42nd and 5th-they have some interesting materials

photo engineer-any ideas why my 4x5s where leaving an inch of so of the image on the last edge in the pod today?-temp in the high 80s the culprit i suspect

will hollar at sue gagnon at polaroid when she gets in but since you might know i might ask-and get an answer

vaya con dios

 

[Photo Engineer]

High temp, high pH and soft gelatin = iffy situation.

I've seen high pH solutions reverse the hardening of gelatin completely by simple hydrolysis. Then you end up a complete mess. If it is at the pod end, that is where the pH is highest.

PE

 

[z-man]

High temp, high pH and soft gelatin = iffy situation.

I've seen high pH solutions reverse the hardening of gelatin completely by simple hydrolysis. Then you end up a complete mess. If it is at the pod end, that is where the pH is highest.

PE

muchismas gracias p e

no time to speak with ms gagnon today so your reply was right on time

you got any thing to say about the pos/neg-not 55-i think 51?

its iso 600+ for the print which is for grafic arts use but the neg is supposed to be medium contrast(?!?!?!?)

non in stock where i usually look so i still can't test

vaya con dios

 

[Photo Engineer]

I know nothing about the other products. Just generalities about the chemistry, and even that is fading.

Sorry.

PE

 

[Mustafa Umut Sarac]

I read your message photo engineer which saying you are sorry to not see the applicants of your posts.
Let me try instant photography. My english is weak and when it comes to 60 years old technical patent english , it is weaker.
I have a polaroid 350 and money to buy hungrian bw photopapers.
I am a practical person .
Now what do I need to do for to get positive , instantly developed and fixed results from the photo paper which is exposed in polaroid 350 .
Let AgX and you write whatever we need , step by step and with explaining how we measure ph and others. What will be the temperatures of chemical mixing stages , how can we do with cheapest , non toxic and easiest to find materials not polaroid patent chemicals.
I did not start to this polaroid business because I could not understand whatever told.
If you are willing to teach to a idiot , you can grasp the fruits from the tree.
I am willing to invest this method and mixing and selling the chemicals.
If I succeed than I will go to kodachrome and try.
If I can do it , everyone can do it.

Best ,

Mustafa Umut Sarac

 

[Photo Engineer]

Mustafa;

Polaroid B&W materials depend on development in an environment high in silver halide solvent, so that the positive image is formed from the salts dissolved as leftover from the negative image. These are depositied on nuclei in the reciever sheet from the donor sheet (the original exposed negative).

Imbalance results in loss of speed and tone scale.

So, with balance, you get both a positive and a negative. The positive is what we generally want, but sometimes we want both. Polaroid has offered products that do both.

In any event, the dissolved silver halide (positive) migrates to the reciever sheet and precipitates out to form a positive image by reduction and we have both a negative and a print.

This is B&W silver only.

In color, the color dyes are hydroquinone containing azo dyes. They dye that developes silver becomes a quinone and is insoluable. The remainder (positive) is soluable and migrates to a mordant sheet. This forms a positive image.

Neither method was in the capability of Land, so Kodak made the original materials, but they were made under strict secrecy according to agreements between companies.

The result is that I know little about the materials due to that secrecy. Kodak would not let employess know what was done between companies.

PE

 

[Redf]

It took 6 years.
Maybe somebody can boast a recipe homemade instant photo?

 

[darkosaric]

It took 6 years.
Maybe somebody can boast a recipe homemade instant photo?

Hi Redf,

I think fastest way to home made instant photos would be to follow http://new55project.blogspot.de and try to make similar solution in format you want.

regards,