>On Mon, 3 Jun 1996, Peter Charles Fredrick wrote, a propos of my
explanation that the Anderson "pigment in gum test" is worthless &
irrelevant:<
I think we have now very effectively, put this one to bed
> The scientific method for testing out a change in excepted practice is for
> several experts to conduct independent tests then confer and verify any new
> conclusions reached.
I doubt this practice has been all that "accepted." It's been in
the books, is all, & I may have made plain I consider that no recommendation.<
You may not consider it accepted, but this does not mean it isn't. The
Scientific Abstracts Published by the RPS is constantly using this method
of comparative study to define standards and authority in emulsion
mechanics relating directly to photographic imaging, In fact in a rather
chaotic way we are doing just the same, on this list. I would like to see
us working in perhaps a slightly more ordered fashion.
> Now we have some real facts to work on., but unfortunately these are
> negative facts we know that the Anderson test for pigment staining does
> not work.So what does ? or better still how can we devise a test that
> will.!
>I believe I have -- as in Anderson's approach, each pigment has to be
tested for each paper, but it has to have the Dichromate included as well
as the gum. This is of course assuming you require perfect control.<
I agree but Iv had almost to squeeze it out of you....
> > a herculean task , but it is perfectly feasible to have a simple
system > that contains known parameters, by which pigment stain could be
measured, > a kind of bench mark by which a new combination could be
judged. It would > be great if this benchmark arose out of a communal
endeavour instigated by > this list. <
>Peter, my experience is that each combination works differently<
We can assume that from this experience of yours, reliable testing
procedures are not feasible. Here I must respectfully disagree, if a method
for measuring the stiffness of a jelly has been found and works very
efficiently, as in the Bloom index, I am sure that a method of testing
pigment stain in a scientific manner is also feasible, indeed there may be
some body, who has a very good working method in another pigment related
field.
Once again if some of our conservator colleagues who tend to have a wider
understanding of materials study perhaps could chip in with expert opinion ?
>speaking of puritanical, some people *like* pigment stain. As I've
suggested here and there, pigment stain is only the great Satan when
you're doing all those coats..<...
I accept the criticism of being puritanical in respect to pigment stain, I
have had a running battle with this tyrant for the past 20 years, I had to
abandon gum Arabic,,and gloy as a colloid ,reject paper as a substrate,
and develop the Fotempera process to finally vanquish this insidious
demon,But this is just a lame excuse, we have a rather earthy saying in our
country, don't let the kettle call the pot, black arse. ;-).
Thanks for the ride Judy
pete