Re: FW: UV blocker in TMAX100 base?

To test the actual effect, one could expose a step tablet together with
another step tablet covered by a processed, blank-area of TMax film and see
the difference between the exposure need to reach the same density.

Dave S

----- Original Message -----
From: "Sandy King" <sanking@CLEMSON.EDU>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, February 24, 2004 12:53 PM
Subject: Re: FW: UV blocker in TMAX100 base?

> On 24 February 2004 Bruce Kahn wrote:
>
> >
> >Sandy, you are correct that T-Max appears to have a UV absorber in it.
> >
> >I am currently teaching a course on 19th Century photographic
> >process. A graduate student noticed some interesting differences
> >between different negatives (T-Max and Ilford FP-4). I did some
> >quick absorbance measurements for some of the materials that
> >students were printing using a spectrophotometer. I have posted
> >some of this data at
> ><http://www.rit.edu/~bekpph/historic/films.jpg>. As you can see,
> >T-Max absorbs UV from ~ 320-410 nm. There is a fairly narrow UV
> >transmission window at about 320 nm.
> >
>
>
> Certainly nice to have confirmation of of the UV blocker in this film.
>
> My hunch from looking at your data is that this UV blocker would have
> more impact on the colloid processes (which are most sensitive to UV
> radiation below 400 nm) than it would on the iron processes (which
> have a lot of sensitivity above 420 nm). Also, one would expect that
> the impact would be greater with UV sources such as BL and BLB tubes
> and NuArc platemakers (which put out most of their radiation below
> 420nm), than with a tube such as as the Super Actinic that peaks at
> around 420nm.
>
> Sandy King
>
>
>
>
>
Received on Tue Feb 24 12:08:45 2004