What was "Kodak Infrared"?

[ntenny]

I've just received a somewhat-outdated box ("Develop before June 1950"!) of sheets of something just called "Kodak Infrared". The code notch is a single rectangle; there's a stamp on one end that might be an emulsion number, but it's not all there---it looks like it starts with B6130. The back says "use Wratten Series 7 safelight", which I guess means it's blue-blind.

Of course I'll be astonished if I get anything useful out of it, but I've had occasional successes with really old film, and if it doesn't work, oh well. I'd just like to know, before I start playing around, what I'm working with here---is it similar to HIE? I'll be using an 89B filter.

Thanks---any information appreciated.

-NT

 

[PHOTOTONE]

Well in 1950 it wouldn't be "high speed" by any stretch. Since Infrared sensitized film has the poorest shelf-life of any film, if this is indeed an infrared film, then there is really little hope of it being good.

 

[AgX]

The back says "use Wratten Series 7 safelight", which I guess means it's blue-blind.

There is no emulsion which is blue-blind.
You cannot extinguish the intrinsic sensitivity of the halide to that part of the spectrum.
(Depending of the kind of halide they differ in how far their sensitivity goeys beyond the UV-part into the visible blue-part of blue.)

Or did you refer to the filter? ('Blind´ to my understanding is related to (someone) something which is sensitive.)

 

[PHOTOTONE]

There is no emulsion which is blue-blind.
You cannot extinguish the intrinsic sensitivity of the halide to that part of the spectrum.

I know you mean this statement in relation to the safelight, but of course you CAN filter out the blue component of natural light via filters on the lens, thus rendering the film in effect (when taking the photo) "blue blind". Also, as a side note, you can desensitize film by treating it in a "desensitizer" such as pinakryptol green, allowing for development by inspection under subdued lighting.

 

[AgX]

Kodak started manfacturing a IR-sensitive film in 1932.

Back in time many years there were a lot of IR-emulsions on the market, of different manufacturers. (I counted 8 manufacturers so far.)
Some of them were were sensitized beyond 1000nm.

 

[AgX]

Phototone,

I refered by `extinguish´ to the character of the emulsion.
But you are right in a way concerning desensitation. "The dye is both a spectral sensitizer as desensitizer." (Mees & James) Which means that a spectral sensitizer has an advert effect on sensitivity on that part of the spectrum for which it does sensitize. And beyond that there are dyes which not even sensitize but still have a desensifying effect.
Though, to my understanding(!) there are no dyes which desensify to an effect that one could speak of extinguishing the halide's intrinsic sensitivity.
Nor do I know of any emulsion where this has been tried in manufacturing.
(But of course I'm open to be corrected.)

 

[AgX]

In a 1967 edition of their scintific materials catalogue Kodak shows several spectroscopic plates and films with IR-sensitivity. Concerning films (and other than HSI) there were`I-N´(925nm),`I-M´(1000nm) `I-Z´(1100nm, hypersenitized).
But I did not find speed nor notch indications.
But as Kodak recommends only these films and HSI for infrared photography one could deduce that your film once stretched beyond 900nm too.

 

[AgX]

I overlooked a Kodak infrared photography booklet from 1961…

There it is stated that they have got aside from HSI a type IR 135 and an Infrared Sheet Film.

The latter two have got the same wedge spectral curve, showing a sensitivity at blue and red/infrared (thus the green lab lighting).
However they have got a different speed.



Infrared Sheet Film

The notch code is a horizontal rectangle.
It reaches up to 865nm.
The EI for use at tungsten(!) light and a Wratten type25 filter in D76 is: 10ASA
(For the HIS under such conditions would be: 160ASA)
Development time for the sheet version is given with D-76 as 6.5 min for a gamma of 0.8.



(The interesting thing about the 135 version is that it has got an opaque leader to avoid the light piping effect we nowadays experience with converted Agfa films on clear PET base.)

 

[AgX]

Concerning the vast speed difference between that sheet film and the HSI (HIE), I guess (one can’t deduce that much from a single wedge spectrogram), the former would look a bit better in relation if an IR-filter would be used.
The HIE is rather a panchromatic film with additional strong IR-sensitivity. The sheet film seems to be sensitized only with an IR-sensitizing dye with reduced sensitivity at the red end. Using a red filter as type 25, would give the HIE quite some red radiation for which it is more sensitive than that sheet film, thus enhancing the speed difference.

 

[nworth]

Over the years, Kodak made a number of infrared sensitive emulsions. I found one matching the description you gave (notch code) in a PLI dating from around 1950. Kodak recommended an approximate exposure index (tungsten) of 8 with a No. 25 filter for this version. Recommended development was 8 minutes in D-76 (undiluted).

A bit later, Kodak made an infrared film in various sheet, roll, and 35mm formats with a recommended EI of 20 under similar conditions. This film continued until at least the mid 60s, and it was produced concurrently with High Speed Infrared. They also made an infrared movie film with a recommended EI of 16.

 

[ntenny]

Infrared Sheet Film

The notch code is a horizontal rectangle.
It reaches up to 865nm.
The EI for use at tungsten(!) light and a Wratten type25 filter in D76 is: 10ASA
(For the HIS under such conditions would be: 160ASA)
Development time for the sheet version is given with D-76 as 6.5 min for a gamma of 0.8.

Thanks! That's clearly it. The low ASA actually gives me a bit more hope, on the theory that slower films take longer to die, but I'm still assuming this is unlikely to work out. I'll get around to it just as soon as I finish a few thousand other critical projects.

I wonder what on earth the tungsten-light thing is about? Do they really put out useful amounts of IR?

-NT

 

[Tim Gray]

Yeah, tungsten bulbs do put out IR. I found this on the web, can't vouch for any of the details:

http://www.assumption.edu/users/bniece/Spectra/HiResolution/Wg.pdf

Black body radiation is moves towards the IR at lower black body temperatures, so tungsten lighting (~3200 K) has a decent amount of IR in it. The wiki article on color temperature has a spectrum pretty far down in it of tungsten lighting and fluorescent lighting and you can see how heavily weighted the tungsten spectrum is in the long wavelengths.

http://en.wikipedia.org/wiki/Color_temperature

I'm actually getting a little easy to use spectrometer in the lab shortly and might make up a couple of spectra of various light sources - could be interesting (not that it hasn't been done before).

 

[AgX]

Tungsten lighting is a heat radiator, thus radiating IR-light.
Actually the vast majority of its energy output is IR (read: heat) radiation. Thats why they are not economical for visible lighting and to be banned...

(Though that mustn't make you hold your hand in front of an electronic flashlight... still some IR-radiation...)