From: Katharine Thayer (kthayer@pacifier.com)
Date: 09/29/03-09:49:55 AM Z
Judy wrote:
Here's the last paragraph of the Keepers of Light gum chapter (p.212).
Crawford has just finished laying out the "Dot Test":
QUOTE:
The dilution of the pigment/gum mixture by the sensitizer actually has
no
effect on staining. What is important is the relationship between a
specific amount of pigment and a specific amount of stock gum solution.
Once these two are combined, further dilution by the sensitizer dilutes
both, while the tendency to stain remains constant.
and Don wrote:
Judy and Keepers of Gum,
Why don't we just ask him? He was at APIS so he must be around. Maybe he
even lurks on this list. Since you are challenging his conclusion about
staining I think the fair thing to do is get his side
of the story.
_______________________________________________________________________
I say:
Since this discussion keeps going on I can't resist one more try to get
my point across to the multitudes. Let's pose it in hypothesis-testing
language to make it very clear.
Hypothesis:
The addition of dichromate to the pigment and gum makes no difference in
staining.
I am willing to assume that Crawford has tested this hypothesis and
found it to be true, and that's why he says that the dichromate makes no
difference, although he goes on to speculate about why it makes no
difference, and his speculation leads him wrong, I think. But his
finding, that the dichromate makes no difference, is not diminished by
his speculation about the reasons for the finding. Scopick has tested
the hypothesis (as he reported himself to the list a year or two ago
when this came up before) and found it to be true. I have tested this
hypothesis and found it to be true.
Others have tested the hypothesis and found it to be false, but have
come up with differing conclusions about how adding the dichromate
affects stain. Some, such as Joe, say that the dichromate increases
staining, others say that the dichromate decreases staining, or that it
does different things under different conditions.
Given the differing findings, as I've said many times before, the only
scientifically sound conclusion that can be drawn is that the jury is
out and that there must be other variables accounting for the difference
in findings. What I always tell people is, use it if it helps you,
don't use it if you don't. But to discount all the findings of people
who say that they haven't found that the dichromate makes any meaningful
difference, is not scientifically sound.
All I can say, from my own personal experience, is that one afternoon
with the pigment test, or a rough version of it, ended staining for me
forever. Forever. To me, it's what works that matters, not whether
someone thinks it SHOULD work or not. It's the empirical results that
matter.
Katharine Thayer
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