From: J. Wayde Allen (wallen@lug.boulder.co.us)
Date: 11/08/00-05:43:54 PM Z
On Wed, 8 Nov 2000, Judy Seigel wrote:
> > I'm assuming that your exposed and developed test strip is paper that has
> > been sized, hardened with Glyoxal, coated with the gum emulsion, exposed
> > for some length of time, and then water developed? Are you exposing
> > through a step tablet?
>
> Yes.
Yes to which?
> > that it was simply the dichromate that caused the effect. Could the
> > exposure have also played a role in the staining?
>
> You mean expose the paper to UV light with no added emulsion?
No, you said that you were exposing your test strip. Could this exposure
you are doing have an effect on the staining?
> That would
> be a 2nd variable, and certainly a good one.
I lumped that in as an environmental factor. In other words, I would
consider the ambient illumination where you setup your test.
> The paper that stained was rinsed in water immediately after glyoxal, and
> when I discovered the stain given another long soak ... So if the water
> development *prevented* the stain, it did so in some as yet inscrutable
> way.
OK, but is it possible that it has an effect or not? Maybe it simply
washed out the Glyoxal? Maybe there is something in the water that
combines with the Glyoxal to either cause or inhibit the stain?
> I've heard of the staining "elsewhere," but my only modus operandi is in
> my own environment. I'm not operative in any others.
OK, but do you even consider changes in your environment? You also do
tend to share your data with others, and have complained on more than one
occasion that these data for your tests often aren't repeatable for
others.
> It was the same paper, which didn't happen to have been hardened yet,
> though some of it was gelatined.
OK, that helps. Were the test strips completely covered, or partially
covered? Did the staining occur only under these sheets or where they may
have been exposed? In other words, is there something here that you can
use to eliminate a possible variable such as exposure to ambient light, or
is there a possibility that this created the conditions for a chemical
reaction. Trapping of Glyoxal vapor perhaps?
> All are constant (though my paper that stained was probably dimly lit, my
> student's paper that stained was in a drawer) except the weather changes,
> but some of the non-stainers are years old, done in all seasons.
You can't say that "all are constant" and then cite exceptions. The way I
see it:
Paper substrate - Controlled
strips covered by paper or not - Probably controlled
Type or brand of gelatin sizing - Controlled
Pigment type or brand if any - Hard to say based on following
dichromate type - Controlled
exposure - Controlled
development water - Hard to say
environment - Not in control
> *pigment* involved is on the exposed and developed strips in the folder,
> which did not stain. Since these run the gamut, probably 50 colors on 10
> or 15 papers, & several gelatins, I discount those factors.
OK, the pigment factor is not controlled. I take it it is NOT even a
factor in your comparison strip. If not, you are probably trying to
compare apples and oranges.
> > have also seemingly ignored several possibly key variables:
> >
> > other paper in contact with strips
>
> which strips? the uncoated as noted above. The coated stacked with same,
> in folders.
Yes
> Sample coated strips developed over a period of several years, with
> "available" water. Unless sudden change in water here this year and in
> Brooklyn last year, not a likely factor.
Since I've been blasted before about the possibility that water changes
from place-to-place and that it can effect alt chemistry, I'm surprised at
dismissing this one so easily.
> > exposure
>
> As noted, same exposure or lack thereof.
OK, but did you expose the so called blank strip that had no dichromate in
it?
> What you seem to be saying is that unless I have a "clean" temperature -
> humidity controlled lab with distilled water, forget the question. Thanks,
> but that says give up without a try.
I didn't say that at all. How difficult would it be for you to put a
thermometer next to your test setup, maybe make a light meter reading,
note differences in what is in contact with your test strips, etc.? I'm
not saying to give up without trying. You are simply suggesting sweeping
things under the rug. Ignoring such things doesn't make them go away.
> Is that your Querulous Variables
> Theory (sorry having a senior moment, forgot the term)?
OK, if you are taking this as quarreling, that was not my intent. You
challenged me to go through this exercise with YOUR test, and I'm
attempting to do that.
> Needless to say,
> most of the questions you ask above about variables were reviewed mentally
> (though not in public e-mail) & discounted for reasons given.
What reasons given?
> > That is what I understand about your test. You'll have to correct any of
> > my mistakes and misunderstandings before we can look at this much deeper.
Not exactly, but I do need to know what you are trying to determine. So
far that is the most important question that you have not answered. If
you did I missed it.
> Still hopeful, I await your prescription.
My prescription, if it must be called that, would be is to define what it
is you are really trying to test, and then identify all of the possible
variables that might affect your test. Heck, make a list of them. Then
you can at least identify which ones you can and want to control, and
eliminate others if you can explain why they aren't important. There is
nothing magical here.
In this case, it looks to me like you have a staining problem but don't
really know what is causing it. What I think you need to do is try and
list all of the variables you think may be causing the problem. If you've
got only a very few variables by all means run all permutations of these
variables. That works fine. If however, you've got a good number of
variables to test. You probably need to resort to a screening style,
multi-variable experiment. The whole point of such a test being to
identify those factors that affect your response (cause staining in your
case).
I was planning on helping you work up to the test design, but at this
point it looks like things are starting to get contentious again. Not
much point in trying to show you how this works if you don't want me to.
I've provided references in my previous posts for those who are
sufficiently interested to pursue this further, and I'll stop boring the
list.
One final point to consider is that the so-called scientific method is
based on repeatable results. If you have tests that are not repeatable in
different labs, you can't really say that you understand or even have a
valid test.
- Wayde
(wallen@lug.boulder.co.us)
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