Digital BW, The Print

Thanks, Tom, for the excellent information.  Up until recently almost
everything I've done has been TriX in D76 1:1, or Bergger or TMax in pyro.
But, I really like the look of the Portra, and digital ice works with it
when needed.  I knew it wasn't archival, but -- I need to get off my duff
and get a fridge for it.

  --Jeb

>  Portra 400 b&w is not an archival film.  It is chromogenic.  When the
Great
> Yellow Father speaks of "Excellent Latent Image Keeping" in the sales
pitch,
> they are referring to the amount of time between exposure of the film and
> it's development.  The reason of course is nothing to do with Portra film
> itself, the problems of delayed processing of color emulsion film is
changes
> in color balance, and since Portra has no color this is not an issue.
This
> has been known by Kodak for years and is why there are "professional"
color
> films as well as amateur that are actually the same film, the only
> difference is the color balance of a professional color film is adjusted
in
> manufacture with the idea it will be frozen until use and developed
> promptly.  Amateur film is designed to be stored at room temperature and
in
> the camera up to six months.
>
> As for archival storage of processed chromogenic film, refrigeration (NOT
> freezing) is required in order for it to last, however I don't know of
> specific life expectancy charts for this particular film.  I would not be
> surprised to see a 3-10 year life for the color version of Portra (meaning
> 15% fade of least stable color layer).  A great analogy is the difference
> between dye and pigment printers, that is the difference between single
> layer color film marketed as B&W, compared to real silver emulsion B&W.
> Here is what Wilhelm has to say about the overall archival considerations
of
> chromogenic (pg 23) "Among the available color processes, chromogenic
films
> and prints as a group have the distinct limitation of being relatively
> unstable in dark storage.  While most classes of dyes are subject to light
> fading, chromogenic dyes are almost unique among commercially available
dyes
> in that many of them also have poor stability when stored in the dark
unless
> kept at refrigerated temperatures."  I might add here that EK knows all
> about this, and if Portra film had a good life expectancy rating you can
bet
> they would make a big deal about it.  For details of storage
recommendations
> for photographers, check Wilhelm's book chapter 19 "Frost-Free
Refrigerators
> for Storing Color and Black-and-White Films and Prints" or else just go
get
> a Kenmore true frost free (not cycle defrost). If you don't mind a used
one,
> they can be had at auctions for $100 or whatever.
>
> best regards,
> Tom Robinson
>
>
>
>
>
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