[Tig] Nitrate, IP, Technicolor, Reversal

Richard Kirk richard at filmlight.ltd.uk
Wed Jul 7 20:56:04 BST 2010

> Ted Langdell <ted at tedlangdell.com> sez...
> On Jul 6, 2010, at 4:33 PM, Rob Lingelbach wrote:
>> I'd like to point some new colorists to some reference clips
>> available on the net that would demonstrate the capabilities or
>> particular properties (looks) of Nitrate, Interpositive, Reversal,
>> and Technicolor films.   Can anyone help in this regard?   Thanks in
>> advance.
>> --
>> Rob Lingelbach  TIG admin
>> rob at colorist.org
> This would likely be quickly answered on the AMIA List... (Association
> of Moving Image Archivists).
> http://www.amianet.org/participate/listserv.php
> I'd be happy to repost this there for you and ask that replies include
> you and/or the TIG.

Ooh, yes, please. If there are good scans of old film print processes,  
then I could try and simulate this. I have managed to model most of  
the technicolor processes, but there is one - the two-colour strip for  
indoor scenes that used an olive green and an orange dye - that I  
can't get to look sensible. This gave good flesh tones - better than  
the usual red and cyan which gives tuna-pink skin, but it can't do  
skies at all. See, for example, "The Mystery of the House of Wax". If  
I could get the spectrum of the dyes, then I should be able to figure  
out the rest.

> Also think your following post about the Nitrate presentation by BFI
> would be of interest on the AMIA-L.

I am also intrigued by the comments about the wonderful lost looks of  
the nitrate stocks. Surely the nitrate was just a transparent base.  
You could surely have put exactly the same emulsion layer down on some  
other plastic that didn't turn to goo or explode, and get the same  
results. Is the 'soft' look of old nitrate just the lack of the anti- 
halation layer, or am I missing something?

> I am scratching my head about the reference to "nine-strip
> Technicolor."  I'm aware of several two-color one-strip and two-color
> two-strip, and of course the one most of us remember three-strip, used
> for Gone With the Wind, among other features.

I know of no such process, but here's a guess. When people used to do  
CMYK printing, this was done by printing through red, green, and blue  
filters, and a 'straw coloured' filter for the black. You could then  
get a set of lighter reversed prints, which when combined with other  
channels of the original four separations could produce a print with  
some cross-colour correction. This took 24 exposures to produce a  
single color CMYK halftone print.

For colour film printing, you might get...
Cyan printed from Red + weak reversed green + weak reversed blue
Magenta printed from Green + weak reversed red + weak reversed blue
Yellow printed from Blue + weak reversed green + weak reversed red

That would be nine strips. Now, I am not sure you need the red-blue or  
the blue-red decoupling, so you could probably use less.

In theory you could do a separate black channel. Techicolor did use a  
black & white film base with the sound track and a weak print of the  
green (process 5?), but I don't think they ever had a strong black.  
These days it would be easy to do all this color correction digitally.  
In fact, I bet you could do away with the silver altogether, and just  
implant hydrogen ions in the gelatin layer directly using a proton beam.

Richard Kirk

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