Development times??

If I start from a certain development time recommended by Kodak for TriX
with Xtol at 68degrees. Then if my developer is at a higher temperature,
Kodak's chart shows recommended times for these higher temps. I also have
the temperature graph that appears in the Massive Dev. Chart (the same chart
appears with Ilford products) for extrapolating the a given temp/time
relationship to another temp. Using that graph (obviously a set of linear
relationships) I find that these times are quite far off from the times in
the Kodak tables for other temps. (maybe 15-20% off at 75degrees). Can
anyone explain why that might be so? I would tend to follow Kodak's
recommendations, but does this mean that, for example, most other developers
follow a more linear set of time/temp relationships and Xtol doesn't???

Thanks for any light someone can shed on this matter


Sam




Sam G

I have found from experience that the Kodak tables, where they exist,
are more reliable than the Massive Development Chart. In any case, if
you can do a test development, say of a step wedge, that would be the
best way to verify which to use.


Francis A. Miniter


Sam G wrote:

>If I start from a certain development time recommended by Kodak for TriX
>with Xtol at 68degrees. Then if my developer is at a higher temperature,
>Kodak's chart shows recommended times for these higher temps. I also have
>the temperature graph that appears in the Massive Dev. Chart (the same chart
>appears with Ilford products) for extrapolating the a given temp/time
>relationship to another temp. Using that graph (obviously a set of linear
>relationships) I find that these times are quite far off from the times in
>the Kodak tables for other temps. (maybe 15-20% off at 75degrees). Can
>anyone explain why that might be so? I would tend to follow Kodak's
>recommendations, but does this mean that, for example, most other developers
>follow a more linear set of time/temp relationships and Xtol doesn't???
>
>Thanks for any light someone can shed on this matter
>
>
>Sam
>
>
>
>