Photochromic or photoreactive autochrome

nmp · Oct 27, 2018

jsmoove said:
Ok thankyou. So the dyes I linked are just sensitizing dyes then? They don't absorb certain wavelengths of light and then in turn change into that specific color? Like from colorless to color? Or from one color into another color?

No, they are not "sensitizing" dyes which is a specific term used for dyes that make other material "sensitive" to wavelengths that it is not otherwise to. In the context of silver based photography, they are used to change the sensitivity of silver halides to a broader spectrum than just UV-blue region that it would be otherwise restricted to - making it "panchromatic" for example.

The "absorbing" dyes are your simple dyes all around, in printers, on textiles etc. The dyes that are being offered in your link are defined to absorb a certain zone of light. The color then will be complementary to that zone. This is opposite to what we normally are used to think about dyes - when we say they are of a specific color, they are meant absorb all wavelengths except those corresponding to the color observed. They are not going to do anything to your current quest, unfortunately.

Photo Engineer · Oct 27, 2018

All of the above.

MattKing · Oct 27, 2018

Nodda Duma said:
You wouldn’t use a Porsche to tow your boat to the lake similar to how you wouldn’t use those dyes linked above for analog photography even though a Porsche is a really cool car.

Careful with the generalities

It's a Porsche Cayenne.

Nodda Duma · Oct 27, 2018

MattKing said:
Careful with the generalities

It's a Porsche Cayenne.

APUG at its finest. *rolleyes*

Yes you could slap a hitch on it but there’s much better tools for the job (I’d be surprised if anyone outside of Porche’s marketing dept ever hauled a boat w/ their Cayenne by the way).

MattKing · Oct 27, 2018

Actually, it's more common around here to see a Porsche being towed - behind an RV.
I take your point though about better tools, even if I'm one to get a perverse sort of pleasure from things like re-purposing common kitchen items for use in a photographic darkroom.
Which reminds me - I need to do my regular check of the calibration of my film development thermometer (aka digital meat thermometer with stainless steel probe) against my Kodak Process Thermometer III .

J 3 · Oct 27, 2018

I just read Friedman's chapter on bleach-Out processes only lightly skimming the exact chemistry. What he lays out is the development of the idea to Utocolor and then past up into the 20's and early 30s.

The direct dye bleach-Out process (IE not the indirect process of Cibachrome) never made it beyond the stage of laboratory curiosity but developments were made.
At the time of Utocolor the goal was largely a contact paper for reproducing autochrome and other additive processes. This was part of why Utocolor was unsatisfactory. Asking a process of CMY dyes to reproduce an orange-green-violet color system optically was hopeless.
The goal was always a single layer emulsion but they continually ran into problems where the dyes or sensitizers for one color interfered with those of another. This also imposed severe restrictions on which dyes could be used.
There were no dyes that were completely insensitive to blue or uv light making good colors elusive.
That being said those working on this in the day were comparing results to what was achievable with autochrome, and later kodachrome. Today by contrast you can get a color accurate print in seconds from an inkjet and digital camera. The race to get perfect color was won long ago. Any dye-destruction process should probably be evaluated on merits of the artistic possibilities, not technical perfection as a result of the shifting modern focus.
Exposures in the neighborhood of a 15min contact print in sunlight looked achievable.
The description somewhat differs somewhat from the 1907 article. The book says the inventor preferred gelatin emulsions but the paper describes a colodion one.

Photo Engineer · Oct 27, 2018

Utocolor was commercialized IIRC, as a print paper. It was never widespread in use.

UV sensitivity can be eliminated almost completely by using a UV filter during exposure. In fact, all modern lenses and color films incorporate UV filters to prevent UV "overexposure".

There is a good Wikipedia article on this topic.

PE

jsmoove · Oct 27, 2018

Haha, thanks everyone. @nmp Ah....thanks. @J3
I realize it doesn't make sense in modern times to be looking for such a thing when we have stuff like inkjet....
I wonder about Ag-TiO2. Maybe we'll have stuff like "smart ink" soon like they say.

J 3 · Oct 27, 2018

Photo Engineer said:
UV sensitivity can be eliminated almost completely by using a UV filter during exposure. In fact, all modern lenses and color films incorporate UV filters to prevent UV "overexposure".
PE

Btw I really admire your knowledge and expertise. I've got a copy of your book on making emulsions and it's quite exceptional and eminently practical.

On this issue of UV sensitivity the situation was somewhat complex. Some of the dyes they wanted to use actually required uv light to activate in addition to target light. This would of course preclude a uv filter before that layer and make results unpredictable in natural light. You're right though, the uv wasn't the big problem but rather the blue light sensitivity. Film of course puts a blue blocking filter after the blue layer but this cuts a couple stops worth of light and makes the product much more complicated. I'll need to read a bit closer but it seems the best that was obtained with dye-bleaching was a two emulsion system where 2 colors were carried in a gelatin carrier and one in a colodian emulsion.

Anyhow Friedman seems like a really good book and much more comprehensive on the topic of color than the section within Haist's 2 volume set. It's an older book though and limited to what was public and known at the time.

Nodda Duma · Oct 27, 2018

Here's a fun tangent from my industry: Voxtel Opto in Oregon has a process to print gradient-index lenses on modified professional inkjet printers, using specially-developed nano particles mixed into UV-cure liquid. The amount and style of particles determine the index of refraction, so they basically load up several cartridges with different types to "print" the gradient profile one layer at a time, curing the liquid each pass. The lenses are printed as flat disks in about an hour and have optical power. The examples I checked out were 1" diameter, 3 mm thick and had focal lengths ranging from 50-150mm. There are numerous applications that this would benefit, but the application I was looking into them for was head-mounted night vision optics to reduce the weight on the user's head (important for pilots). That was a couple years ago.

J 3 · Oct 27, 2018

jsmoove said:
Haha, thanks everyone. @nmp Ah....thanks. @J3
I realize it doesn't make sense in modern times to be looking for such a thing when we have stuff like inkjet....
I wonder about Ag-TiO2. Maybe we'll have stuff like "smart ink" soon like they say.

I'm not so sure about it not making sense so much as it just doesn't make the same kind of sense today as it did back when no one knew the answers and every technology was potentially one breakthrough away from perfection. Plenty of people still draw and paint even if fast photography has taken over the cultural role of how you capture a visual impression. For myself Im looking at Ag-CrO4. I was reading a Getty article on collodian on paper and ran into a reference that listed silver chromate papers as a late stage developement before colodian papers died commercially. I didn't even know silver chromate was light sensitive so I'm trying to find out what's that old paper was about.

Photo Engineer · Oct 27, 2018

J 3 said:
Btw I really admire your knowledge and expertise. I've got a copy of your book on making emulsions and it's quite exceptional and eminently practical.

On this issue of UV sensitivity the situation was somewhat complex. Some of the dyes they wanted to use actually required uv light to activate in addition to target light. This would of course preclude a uv filter before that layer and make results unpredictable in natural light. You're right though, the uv wasn't the big problem but rather the blue light sensitivity. Film of course puts a blue blocking filter after the blue layer but this cuts a couple stops worth of light and makes the product much more complicated. I'll need to read a bit closer but it seems the best that was obtained with dye-bleaching was a two emulsion system where 2 colors were carried in a gelatin carrier and one in a colodian emulsion.

Anyhow Friedman seems like a really good book and much more comprehensive on the topic of color than the section within Haist's 2 volume set. It's an older book though and limited to what was public and known at the time.

Try Hanson's book or Hanson, Evans and Brewer on color.

PE

J 3 · Oct 27, 2018

Photo Engineer said:
Try Hanson's book or Hanson, Evans and Brewer on color.
PE

Thanks. I will certainly do so.

Photo Engineer · Oct 28, 2018

I got it backwards. It is Evans, Hanson and Brewer. And another book is volume 2 of the Haist series.

PE

Photochromic or photoreactive autochrome

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