Being a liquid concentrate makes a difference. I could not
even find that out. Phenidone is not considered hazardous so is
left out of most MSDS. Its also usually present in quite small
amounts. I suspect the "others" are borax and boric acid as in
Microphen or something that becomes them in solution. The
dilution is not directly comparable to a developer mixed from
powder because the stock solution can be of quite different
concentration. Some clue might be had by comparing developing times.
On 12/15/2020 1:54 PM, CarlosMFreaza wrote:
Hi Richard:
You are right, the PQ7 has 16% to 16,5% hydroquinone, 8 to 8,5% sodium sulfite, 5% potassium bromide, 64 to 65% distilled water and 8 to 8,5% "others" according the data in the plastic bottle for the concentrated solution, that "others" is for the "phenimek"/phenidone according reliable data. You need to use it diluted 1 developer: 3 water, it's the only dilution the manufacturer recommends. The working solution could be used to develop 8 120 film or 8 35mmx36 frames or equivalent, you need to increase 10% the developing time after the second film you developed.
The data sheet for this developer says it has a basis of "phenimek", but it does not appear in the bottle data, it must be "others" as I explained. I have used Ilford Microphen several times, Microphen is a powder developer and it has different developing times and can be used as a stock solution or diluted with different results, PQ7 is 1+3 only.. Liked very much the results I obtained with the PQ7 and Ilford 3200 film
This is the only data sheet available in the web for the PQ7, developing times suggested for differents films are a good initial recommendation IMO (there is a "+" sign at the end of the first page to enlarge the leterrs size):
https://es.slideshare.net/hernan030/revelador-pq-7 <https://es.slideshare.net/hernan030/revelador-pq-7>
Carlos
El mar, 15 dic 2020 a las 17:52, `Richard Knoppow (<dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>>) escribió:
I was unable to find any information on this on the web. The
manufacturer has a web site but it only displays various
developers. Its on the giant developer chart (drawing a
blank on
its right name).
My guess is that the PQ means phenidone hydroquinone If so
that might make it similar to Ilford Microphen. Microphen is
similar to a phenidone version of D-76. I think Ilford has a
published formula for something similar but can't remember its
number off hand. Microphen is a good, general purpose, fine
grain
developer which in comparison to D-76 delivers slightly finer
grain and slightly higher speed. I am a bit puzzled by the
dilution. For Romek its given as 1:3. So either its more
concentrated than Microphen or is a different developer.
Ilford
does give instructions for Microphen diluted to 1:3. At that
dilution is becomes a high definition developer. Actually,
D-76
does too. Kodak does not give times for 1:3 but Ilford does
for
ID-11 which is identical. I've tried it and get a very strong
edge effect but don't like the way it looks.
AFAIK, the patents where they ever existed for all these
developers has long expired so anyone can make something like
Xtol, T-Max, Microphen, Microdol-X, etc, etc.
Several modern developers use Phenidone in place of
Metol and
ascorbic acid in place of hydroquinone. Generally, Phenidone
yields slightly higher speed than the metol equivalent.
Back in the 1930s C.E.K. Meese, the founder of Kodak's
research lab, said that the great number of developers only
showed how many ways there were of doing the same thing.
Also, those of us in the U.S.A. have the advantage
that we
can buy nearly anything even despite some EPA regulations
where
in other countries there are import restrictions or other
barriers.
On 12/15/2020 1:17 AM, CarlosMFreaza wrote:
> Hello Louis:
> Thank you. I like B&W very much, anyway I
> also like to shoot color sometimes. Romek PQ7 is a developer
> manufactured in my country, the factory info about this
liquid
> developer is basic; it's an ultrafine grain developer on the
> basis of an element they call "phenimek", I guess
phenidone, an
> Ilford trade mark. I use it because I like the results
most of
> the time and it's available here regularly, at least so
far; I
> have used several other developers like Agfa Rodinal,
D76, both
> Tmax, Perceptol, Microphen, Tetenal Ultrafin Plus, I
liked all
> them, but some of them are not available here sometimes
or they
> become more expensive due to the exchange rate, therefor I'm
> using the PQ7 from some time ago. There is some
additional info
> and feedback about the PQ7 from users, but most in Spanish.
>
> I liked your photographs at Flickr, nice light and good
contrast.
> Carlos
>
-- Richard Knoppow
dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>
WB6KBL
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