Default Silver Halide Sensitivity

Silverhalide Emulsions / Chemistry.
Grayham
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Joined: Wed Feb 11, 2015 12:56 pm
Location: Hampshire, UK

Default Silver Halide Sensitivity

Post by Grayham »

Hi,

I have been making my own silver halide plates with varying degrees of success(and failures :) )
To pre-sensitise my plates I currently use an Ascorbic acid bath but am starting to look at TEA and other methods.

I know TEA gives you about 2 x the sensitivity of an un-sensitised plate but can't find any information on the increase of sensitivity with an Ascorbic bath.
If the Ascorbic acid is on par with TEA i'm thinking I could maybe leave it out of my process and expose just a little longer.

Anyone have an idea of the increase in sensitivity provided by the Ascorbic acid bath please?

Thank you
Grayham
Martin
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Joined: Sat Apr 04, 2015 2:36 am

Re: Default Silver Halide Sensitivity

Post by Martin »

Hi,

I assume it's difficult to give an exact figure on the speed increase by ascorbic acid since it may also depend on other factors like: the kind of gelatin, AgX concentration etc.
I would have expected the speed increase to be in the 5 - 10 x range.
As for TEA treatment, as you know, you'll get a "blue" shift with reflection holograms.

By the way, what method are you using for your AgX plates: diffusion method or some kind of double jetting?
Grayham
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Joined: Wed Feb 11, 2015 12:56 pm
Location: Hampshire, UK

Re: Default Silver Halide Sensitivity

Post by Grayham »

Hi Martin,

5 -10x would be a lot to give up :) I'll guess I will keep doing that.

I'm working on a very simplified diffusion method that allows me to make a lot of 10x10cm plates quickly and cheaply
I have read both Jeff's and Han's methods and am basing a process on the supplied information but with some simplifications to speed the process up.

Definitely going to look at a double jet method at some point but want to pin this down first.

I made a nice hologram of a dragon on Saturday and accidentally sprayed it with white paint instead of black, duh :(

Kind Regards
Grayham
Martin
Posts: 131
Joined: Sat Apr 04, 2015 2:36 am

Re: Default Silver Halide Sensitivity

Post by Martin »

Grayham wrote: Mon Oct 29, 2018 4:08 am I'm working on a very simplified diffusion method that allows me to make a lot of 10x10cm plates quickly and cheaply
I have read both Jeff's and Han's methods and am basing a process on the supplied information but with some simplifications to speed the process up.

This is good news. Looking forward to learning about your simplified diffusion method.
Definitely going to look at a double jet method at some point but want to pin this down first.
Good luck for your projects.
I'm also looking into the possibility of simplifying double jetting. But it will have to wait until I've finished my tests with dye sensitized ferric gelatin (FEG) - not to mention the photopolymers.
I made a nice hologram of a dragon on Saturday and accidentally sprayed it with white paint instead of black, duh
That's very unfortunate but hopefully you'll soon have tons of 10x10cm plates...
dannybee
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Re: Default Silver Halide Sensitivity

Post by dannybee »

I have been thinking on the same thing :) . I like Hans modified of Jeff diffusion method because you can get a lot of silver in the layer. also using ammonia silver nitrate in place of silver nitrate. also been reading old 1800 papers on making old photographic plates . what they use with the gel glycerin (a plasticizer) or like Jeff said to use PVA with gel what this does slows down grain growth. I did do Jeff diffusion method in PVA it was very bright then I tried to bleach it (bad idea) and lost it. also know that you can add dyes after you have formed the silver sensitive layer making it easy to do in orange light until your ready to add dyes
Grayham
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Joined: Wed Feb 11, 2015 12:56 pm
Location: Hampshire, UK

Re: Default Silver Halide Sensitivity

Post by Grayham »

Hi Dannybee

I did try PVA to start with but found it too water soluble to be useful.
As soon as I dipped the dry plate in any kind of liquid it started to melt.

Can you tell me how you managed to keep the PVA from melting please?
Or was it a special brand?

I am going to try adding a dye after I have created the silver as just got myself a red laser so want to try with a little Rhodmaine B :)

Grayham
dannybee
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Re: Default Silver Halide Sensitivity

Post by dannybee »

yes, pva is a nice medium , what you have to do is add dichromate (1%) to the mix, then expose plates to sun and rinse with water and dry. remember you cant bleach a pva holo it will already be ultra fine grain and very bright :) was also thinking of very mild borax will also harden layer
dannybee
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Re: Default Silver Halide Sensitivity

Post by dannybee »

http://www.freepatentsonline.com/2376371.html check this out they use boron to harden the pva and polyvinyl alcohol silver halide emulsions.

"We have found that by the incorporation of but a small amount of a boron compound in a polyvinyl alcohol photographic emulsion at a pH of not more than 6, the emulsion may be readily coated out upon a support such as paper or 0 film base to form a thin layer which is quickly set by fuming with ammonia or the like. "
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