Re: ETHOL LPD

From: Richard Knoppow <dickburk@ix.netcom.com>
Subject: Re: ETHOL LPD
Date: Sat, 24 Apr 2004 01:02:10 -0700

> What kind of results do you desire from the developer?

I'm also curious about that...

> I don't know what is causing the precipitate when the
> Potassium Carbonate is added. Potassium carbonate will
> dissolve in greater quantity than Sodium carbonate but this
> is far less than the amount for saturation of either form.

What's most likely within my guess is that he meant sodium sulfite.
At that concentration, metol should have difficulty in dissolving
especially with 75g/L of sulfite.

> The amount of Metol is about 7 that in a standard print
> developer like Kodak Dektol/D-72. I don't think I've seen
> another formula quite like this.

Well, his formula is metol only and to be diluted 1+3 to 1+8 so this
is reasonable, I think, except I expect metol's solubility will be a
problem. (also, why does he want a metol only print developer? -- this
I don't know.)

> AFAIK, Potassium carbonate can be used in the same amount as
> anhydrous sodium carbonate. There is some controversey in
> the literature over whether there is any difference in the
> performance of the developer with the two salts.

I've seen in some literature citing old literature saying that
potassium salts tend to promote hydroquinone's developing action. You
see in some old AGFA warmtone print developers potassium salts are
specified. But I personally think actual utility of this phenomenon is
pretty much negligible and I also have not made any effort to track
down who said this first on what basis.

Speaking of developers, I found a paper talking about the influence of
developers on resolving power (not accutance) but lost chance to
follow up on that thread. It's one of those papers by Carroll and
Hubbard, and the test emulsions were Seed's 23 plate, Eastman Speedway
plate, and another press plate by other company (forgot). They tried
several developers, including pyro-carbonate, MQ-carbonate, and the
Eastman MQ borax (now known as D-76). The result was negative. No
significant difference in resolving power was found across developers,
despite considerable variation in speed, fog and graininess of the
image. Although their choice of materials were wide enough to answer
some of the Sandy's question, their question was whether fine grain
developer like D-76 would provide superior resolution because of
reduced grain. Either way, the answer was negative.

I do deeply respect this guy Carroll, but I still have to say that the
actual quantity that should be measured in this sort of study is a
modulation transfer at moderate spatial frequency. (but the
instrumentation must have been quite limiting at that time... maybe
Richard knows.)

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)