Tmax & D-76

"Nicholas O. Lindan" wrote in message
m...
"Richard Knoppow" wrote

The line about T-Max being as fine grained in Microdol-X
as Technical Pan in Technidol is from me.

HA! If I could get Google to search rec.photo.darkroom -
I am sure I was pointing this out as early as ...

* * * *

Perceptol - from the MSDS information - doesn't really
look a whole lot like Microdol-X

Part A:
Metol

Part B
S. Sulfite
S. Bromide
S. Tripolyphosphate (STPP)

The STPP is a water softening agent in this application
(among it's other uses it adds weight to seafood by making
it retain water). I don't know if there is a dichroic
fog inhibitor or if the bromide takes care of it.

I guess P. Bromide could be a fine-grain agent, but I
would
wonder about its effect on shadow detail. The only film
developer w/ bromide TIKO (WTEO Perceptol) is D-96, used
by the motion picture industry.

One rather whacked-out developer in the Microdol-X vein
is Rollei RLS (LP Cube XS) that is made from

Metol
Ammonium Chloride

without the s. sulfite (if the MSDS can be believed).

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.darkroomautomation.com/da-main.htm
n o lindan at ix dot netcom dot com
Be careful! The MSDS you have for Perceptol is an old
one and in error. I wrote them about the sodium bromide, its
suppsed to be sodium chloride. Its possible that Microdol-X
has ammonium chloride in it, I think the cation may not be
important. But there are often several versions of MSDS
around. Also, they don't show all the ingredients, only
those deemed to be hazardous and sometimes not even those if
present in very small quantity. For instance both T-Max and
T-Max RS are Phenidone developers but no mention of it was
made in their MSDS for years.
Many packaged developers have some sort of sequestering
agent or agents in them to control impurities in the water,
mostly magnesium and calcium carbonates, the most common
"hardness" in water and sometimes also trace metals like
iron.
I don't have an actual formula for Microdol/Perceptol
but it appears to contain about 15 or 20 grams of sodium
chloride per liter of working solution, otherwise similar to
D-20. I am pretty sure the X in Microdol-X is a silver
sequestering agent, perhaps a mercaptan, to prevent dichroic
fog. I never had any problem with this from Perceptol so
perhaps it too has some anti-silvering agent in it.
Kodak has a ton of patents for anti-silvering agents,
who knows which were actually used and where since they can
also be added to emulsions.



--
Richard Knoppow
Los Angeles, CA, USA