From: Peter Fredrik (pete@fotem.demon.co.uk)
Date: 02/06/01-01:43:31 AM Z
Dear Jeffrey,
"Jeffrey D. Mathias" wrote:
> Peter Fredrik wrote:
> > Yes I did only evaluate in one direction but this did not seem to make any
> > difference to the final results I got from the tests on paper from
> > differing sources, as I had no way of knowing which way the grain was
> > running, ...
>
> One way to check the direction of grain is to humidify the paper on one
> side and observe the curl. The paper should curl so that the trough of
> the curl is parallel to the grain. The paper is usually packaged with
> the same orientation.
Thank you for this insight
>
>
> > ... I think we can discount these small changes a
> > greater problem lies with relative humidity which it seems expands and
> > contracts to a greater extent....
>
> I agree humidity changes can make registration challenging.
> I have also noticed size differences between the directions up to 1/8 of
> an inch over an 8 inch size of papers I typically have used for Pt/Pd
> printing. I would consider this significant enough to check both
> directions for any paper used and requiring registration. Also the
> final dried size may differ from the working size (after coating,
> especially with humidity), and the pre coat size.
Did you pre shrink the paper in the manner I have described in my test ? before
coating
>
>
> I find that if the paper is preprocessed (no coating, water bathes for
> typical times and dried, subsequent shrinking can be made minimal, but
> may still occur for some papers. (Example: Biefang 360 seems to shrink
> twice, and the first time shrinks noticeably different between the
> directions.)
Fine this seems to coincide with my results I will readily take your point that
there will be exceptions to the general rule as in all things and one should
not take anything for granted.
>
> It is probably a good idea to check each new batch of a paper for any
> parameters that may influence results. For example: print quality for
> particular process, strength to survive processing, which side works
> best, and dimensionally stability if registration will be used.
Agreed
>
>
> Checking each new batch is good because even if a manufacturer has
> reliable consistency, they may "improve" a paper without (or with)
> notice that may completly alter its use with an alternative photo
> process.
My mentor Jane Reece has made this same point to me she states individual
manufactures Furnish there papers in different ways and this has a considerable
effect on the final result
>
>
> Has anyone tried laminating the paper negative so as to render it
> impervious to moisture. Some of the laminating films are very thin.
> But perhaps better, select a paper to print on that has the same
> expansion characteristics as the paper negative.
Yes I am in the process of doing this at the moment with the help of my friend
Alex Chater we have had partial success ,but need to do more work before we are
ready to publish the results of our labours.
>
Pete
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