phenidone-aminophenol

Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath

On 29 Nov 2004 01:23:10 -0800, (sreenath)
wrote:

Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath

Congratulations, Sreenath, you have asked a significant question that
has been long overlooked; admittedly, by me, despite long years of
playing with oddball agents and combinations.

I do recall something that was kicked around about combining an Xtol
type of developer with Rodinal, that might serve to get you going. Do
an online search in newsgroups for Vitamin C and Rodinal, as that just
may be the most specific combination.


Robert Vervoordt, MFA

(sreenath) wrote in message . com...
Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath

Why? It would be difficult to combine these developing agents, as
para-aminiohenol is usually used at a very high ph, whereas phenidone
is usually used at a low ph.

Uranium Committee wrote:

(sreenath) wrote in message . com...


Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath



Why? It would be difficult to combine these developing agents, as
para-aminiohenol is usually used at a very high ph, whereas phenidone
is usually used at a low ph.


That's not much of a clue. Hydroquinone is often used at high pH, as is
ascorbic acid, but in combination with phenidone the pH may be much
lower. Phenidone is often thought of as a catalyst for the other
developing agent.

In my experience, p-aminophenol is superadditive with hydroquinone or
ascorbic acid in about the same way as metol. I have not tried it with
phenidone. Phenidone and metol are actually antagonistic in some
circumstances.

On Mon, 29 Nov 2004 17:44:37 -0500, PATRICK GAINER
wrote:

Uranium Committee wrote:

(sreenath) wrote in message . com...


Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath



Why? It would be difficult to combine these developing agents, as
para-aminiohenol is usually used at a very high ph, whereas phenidone
is usually used at a low ph.


That's not much of a clue. Hydroquinone is often used at high pH, as is
ascorbic acid, but in combination with phenidone the pH may be much
lower. Phenidone is often thought of as a catalyst for the other
developing agent.

In my experience, p-aminophenol is superadditive with hydroquinone or
ascorbic acid in about the same way as metol. I have not tried it with
phenidone. Phenidone and metol are actually antagonistic in some
circumstances.

So, you're the one!

Actually, there was at least one other who did some experimenting, but
I forget who it was. That said, I wonder if your experiments might
have included something like the Acufine substitute or Crawley's
FX-11, in which both Phenidone and Metol were used to wring out some
more emulsion speed? I;m aware that you avoid high Sulfite
developers, so you may not have tried them, I did and they did deliver
the goods.

I'm trying to recall another instance of the two combined for some
specific use, but am unsuccessful.

I did use Phenidone and Metol in some of my own Cibachrome
experiments, but, while they worked, they didn't produce the results I
was seeking.

Maybe somone can chime in here.


Robert Vervoordt, MFA

"sreenath" wrote in message
om...
Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath

I don't think they are, at least significantly.
p-Aminophenol is a close relative to Metol but generally
considered inferior to it. Its used in Rodinal because it
will dissolve in enough quantity to make very concentrated
solutions. It was also thought not to a alergin like Metol,
but it turns out that nearly all photographic developing
agents can be sensitizers to some degree.
The interaction of developing agents is complex. The
superadditivity of Metol and Hydroquinone is very well
known. The two tend to regenerate each other even in low pH
solutions like D-76 where the Hydroquinone is not active as
a developing agent. Ascorbic acid is superadditive with
Metol and Phenidone is a similar way to Hydroquinone so can
be used in developers in a similar way but with some
adjustments. I just can't see any advantage to using
p-aminophenol since it was long ago abandoned in all but
highly concentrated developers and has been abandoned for
those in favor of Phenidone (Kodak HC-110, etc.) except for
Rodinal.


--
---
Richard Knoppow
Los Angeles, CA, USA

"sreenath" wrote in message
om...
Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath

I don't think they are, at least significantly.
p-Aminophenol is a close relative to Metol but generally
considered inferior to it. Its used in Rodinal because it
will dissolve in enough quantity to make very concentrated
solutions. It was also thought not to a alergin like Metol,
but it turns out that nearly all photographic developing
agents can be sensitizers to some degree.
The interaction of developing agents is complex. The
superadditivity of Metol and Hydroquinone is very well
known. The two tend to regenerate each other even in low pH
solutions like D-76 where the Hydroquinone is not active as
a developing agent. Ascorbic acid is superadditive with
Metol and Phenidone is a similar way to Hydroquinone so can
be used in developers in a similar way but with some
adjustments. I just can't see any advantage to using
p-aminophenol since it was long ago abandoned in all but
highly concentrated developers and has been abandoned for
those in favor of Phenidone (Kodak HC-110, etc.) except for
Rodinal.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote in message ...
"sreenath" wrote in message
om...
Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath

I don't think they are, at least significantly.
p-Aminophenol is a close relative to Metol but generally
considered inferior to it. Its used in Rodinal because it
will dissolve in enough quantity to make very concentrated
solutions. It was also thought not to a alergin like Metol,
but it turns out that nearly all photographic developing
agents can be sensitizers to some degree.
The interaction of developing agents is complex. The
superadditivity of Metol and Hydroquinone is very well
known. The two tend to regenerate each other even in low pH
solutions like D-76 where the Hydroquinone is not active as
a developing agent. Ascorbic acid is superadditive with
Metol and Phenidone is a similar way to Hydroquinone so can
be used in developers in a similar way but with some
adjustments. I just can't see any advantage to using
p-aminophenol since it was long ago abandoned in all but
highly concentrated developers and has been abandoned for
those in favor of Phenidone (Kodak HC-110, etc.) except for
Rodinal.

Thanks for all the responses.

I have rather large quantities of both these chemicals(phenidone and
aminophenol) and don't want to buy any other developing agents.

Actually, it is not true that aminophenol needs high pH to develop.
There is one Kodak formula DK-93 that uses Kodalk as the alkali. I
have made that developer, leaving the hydroquinone, and even that
develops paper very well. Induction time was more than ID-62, which is
my normal paper developer.

While metol and phenidone are used in very small quantities compared
with hydroquinone, rather large quantity of aminophenol is used. In
DK-93, for 5 grams of aminophenol, there is just 2.5 grams of
hydroquinone. Does that ring any bells?

How does one determine experimentally if phenidone and aminophenol are
superadditive? Any suggestions?

thanks,
Sreenath

"Richard Knoppow" wrote in message ...
"sreenath" wrote in message
om...
Hi all,

Is phenidone-A superadditive with para aminophenol?
Is there a simple experiment to find this?

Any information in this regard much appreciated.

thanks in advance,
Sreenath

I don't think they are, at least significantly.
p-Aminophenol is a close relative to Metol but generally
considered inferior to it. Its used in Rodinal because it
will dissolve in enough quantity to make very concentrated
solutions. It was also thought not to a alergin like Metol,
but it turns out that nearly all photographic developing
agents can be sensitizers to some degree.
The interaction of developing agents is complex. The
superadditivity of Metol and Hydroquinone is very well
known. The two tend to regenerate each other even in low pH
solutions like D-76 where the Hydroquinone is not active as
a developing agent. Ascorbic acid is superadditive with
Metol and Phenidone is a similar way to Hydroquinone so can
be used in developers in a similar way but with some
adjustments. I just can't see any advantage to using
p-aminophenol since it was long ago abandoned in all but
highly concentrated developers and has been abandoned for
those in favor of Phenidone (Kodak HC-110, etc.) except for
Rodinal.

Thanks for all the responses.

I have rather large quantities of both these chemicals(phenidone and
aminophenol) and don't want to buy any other developing agents.

Actually, it is not true that aminophenol needs high pH to develop.
There is one Kodak formula DK-93 that uses Kodalk as the alkali. I
have made that developer, leaving the hydroquinone, and even that
develops paper very well. Induction time was more than ID-62, which is
my normal paper developer.

While metol and phenidone are used in very small quantities compared
with hydroquinone, rather large quantity of aminophenol is used. In
DK-93, for 5 grams of aminophenol, there is just 2.5 grams of
hydroquinone. Does that ring any bells?

How does one determine experimentally if phenidone and aminophenol are
superadditive? Any suggestions?

thanks,
Sreenath

On 29 Nov 2004 01:23:10 -0800, (sreenath)
wrote:

Hi all,

Is phenidone-A superadditive with para aminophenol?

No.

Is there a simple experiment to find this?

The only thing I can think of would be some densitometric
tests showing speed-point comparisons. To the best of my knowledge the
super-additivity feature of PQ and MQ developers depend on the fact
that the by-products of hydroquinone are developing agents in
themselves.

Any information in this regard much appreciated.

I'd try something like the following for a P-pA developer.

5.0g p-AP
0.20 Phenidone
50g Sulfite
2.0g Metaborate

Starting time I would guess around 12 min. at 70F but that's
purely conjecture.
Regards,

John S. Douglas, Photographer - http://www.puresilver.org
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