Digital BW, The Print

Steadman,

>About that Magical Fading Machine you have there...

No magic -- just plain and simple.

>would you please describe it, how it is built (is it a homebuilt?),
>how close the paper is to the light tubes,
>what number of fluorescent watts is involved, what type of bulb,
>what K temp the bulbs are, what temperature the paper surface is
>during testing, and what the relative humidity is in the tester
>on averaged basis?

The fader started life as a standard 10" aluminum photo light reflector.  It
sits facing down toward a white formica counter top.  It is held 1" above
the formica for ventilation.  At the top of reflector, where the light
screws in, I've drilled 8  7/16" holes that vent the warm air out the top.
This pulls the fresh, cool air in the bottom vent.  The paper strips are at
the bottom lip of the reflector, clipped to the edge of it.  The discreet
density patches of the test strips  that I measure are placed at the bottom,
to be as close to the incoming cool air as possible.

The light used is a florescent light designed to replace normal 100 watt
incandescent lights.  The light uses about 20 watts but puts out a claimed
100 watt equivalent.  These lights are now readily available.  I don't know
the K temp.

The paper strips are 3 1/2 inches from the light.  I change the paper
positions during the testing to minimize any differences that may arise from
uneven light distribution.

It's impossible to know what the actual paper temperature is, because the
different densities will absorb different amounts of light and heat up
differently.  The air temperature as close to the paper surface as I've been
able to measure is 12-15 degrees warmer than the room temperature.  The room
temp stays in the low 70's.  I just measured an internal temperature of 82
degrees F using a standard metal photo thermometer placed as close to the
paper surface as I could get it's end (which means it was closer to the
light than the paper, but probably reflected more radiant heat than the
average paper test strip patch).

I don't keep track of humidity.  This is southern California, with generally
moderate to low humidity.

>Also, how "fresh" are the prints when they go in the tester?
>Are they already "cured" and dried or are they still moist
>and "tender" from just coming out of a printer?

I let "new" test strips at least dry overnight, if possible.  However, I
have not detected any difference between really fresh and older test strips.
Of course, the control and test strips must be contemporary.  Here again,
however, I don't see any significant changes in my dark storage prints, at
least over the time periods that would typically be involved.

Actually, the German Etching test strips were sent to me some time ago.  If
they had already warm-shifted in dark storage, we would probably not see the
typical light-effect warming.  They acted just like fresh test strips in the
sense that they warmed in the first 100 hours and then stabilized, for the
most part, with respect to warming.  This is the same pattern I see in
almost all combinations of pigments and paper.  (Dyes may not stabilize in
the same way.)

>How long do you let them dry before doing the "before" scanning?

I scan after the test strips have been in the fader at least 50 hours.
Between taking them out of the fader and scanning there is usually 15 minute
or so.  However, I see no evidence of changes after coming out of the fader.
The dark storage control strips are always, of course, scanned along with
the test strips.

That's pretty much the procedure.  I've probably left something out.  So,
feel free to ask.

One can debate endlessly the merits of this testing, but for me, it works
and is better than nothing.  Frankly, the results I see look a lot like the
graphs MIS put up from RIT.  If all ink and paper sellers would have RIT
tests run and publish the results, that would be terrific.  It's not going
to happen, however.  So, where do we turn?  As crude as my tests are, I
think they are better than the "south window" tests -- faster, more
consistent and repeatable, and probably less heat.  I really have yet to see
results that I think are simply inconsistent with what little other
information is out there.

Paul
http://www.PaulRoark.com