From: Halvor (halvorb@mac.com)
Date: 05/25/03-10:57:54 AM Z
Jeffrey, Eric, Ray
Head bit thick now, just finished a report with a deadline at "noon"
tomorrow as somebody so kindly had translated it to.
but,
I have done a fair bit of tests under varying light sources, meaning the
curves are not directly comparable. Also as I discovered some bulbs do loose
strength over time, might be the electrical system here that varies a bit in
output too, would not surprise me. Started to always make two, later four,
tests each time. One (or 2) for the experiment and one or two basic for
comparison. Result is that one test is coated about 5 min before the other,
having longer time to "soak" the "emulsion". Have then been drying them
together short time after coating the second test. If I had been smart I
should have marked which order they where coated in and I could have seen if
this is the cause of some of the troubles. There is however a definite trend
of two test made in the same way exsposed together, same time, having a
difference mainly in the straight part (well in this of the curve of 0.1 to
0.2 Lg H. Well should be possible to test that comming week.
This beeing Tokyo, Japan, the humidity varies from around 40 % in winter up
to 80 % ,worst case, in summer. I thought I should try to avoid the humidity
influence by exsposing straight after drying the test (with hair dryer), no
re humidification, saves time, but as pointed out for the exsposure time
(Eric), this might amplify smaller mistakes. ???
Have not done anything about humidity before coating, but at least the test
are done from pices of the same paper so that should be equal. Are trying to
limit influencing factors and are using basic mix of of ferric oxalate and
palladium.
Somebody mentioned a while ago the possibility of drying the paper before
coating,,,
Should I instead rehumidify controlled ?
exsposure times when using a 2 kw metal hydrate arch, 60 cm distance, about
5 to 8 min, varies with the test.
or 15 to 60 min sunlight, time of day and weather .....
500 watt tungsten studio bulb 30 cm distance 30 min to one hour, (these
things are losing output with time)
I have not compared level of errors between different light sources &
exsposure times but will keep an eye on it from now on.
ehh.. Wentzel, the emulsion was starting to eat into the step wedge so I
made a couple of copies of it, now this beeing done a bit late, they are a
bit uneven along the edges. A weighted reading is not always too smart, but
are doing three readings choosing the most logical one :) Have been
re-reading when the results looks too stupid, didnīt help. Also the 4 copies
of the step wedge I am using are not excactly similar so I do not do visual
comparisons, only comparing the curves. Steps beeing originally increments
of 0.15 (Kodak 21 step). now varies a bit, Suppose I should add a few step
wedges on my next wish list to my teachers.
I was beginning to loose confidence in the stability of Pd/Pt but thanks for
confirming that the process is stable (Jeffery), and errors are a snapshot
of my working habits. It was becoming a bit frustrating.
okay more later before I confuse this further, but thanks for replies, have
something to work on now.
Halvor
(laid back, enjoying a mental image of Ray beeing chased through Tokyo by
the Austrailian Police on roller scates :)
I have recieved a couple of those mails too though....
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