D-76 to Lc-1

["Gordon J. Holtslander" <holtsg@duke.usask.ca>]

Hi:

I'm an avid using of Dave Soemarko's LC-1 developer.  I did some reading
on developers and looked up the formula to d-76 and comparied it to lc-1.

Below is my understanding of the chemistry involved.  Would some real
chemists clarify this?

D-76 and Lc-1 have very similar ingredients and concentrations.  The main
difference is D-76 has Borax and lc-1 has sodium bisulfite.

These two ingredients are used to set the pH of the developer.

D-76

Water (125F/52C)              750 ml
 Metol                         2g
 Sodium sulfite (dessicated) 100g
 Hydroquinone                  5g
 Borax                         2g
 Cold water to make          1000ml

LC-1

Soemarko LC-1: Stock A
 water                 750 ml
 metol                 3.0 gr.
 sodium sulfite       60.0 gr
 hydroquinone          3.0 gr
 cold water to make    1.0 liter

Soemarko LC-1: Stock B
 sodium bisulfite     10.0 gr
 water to make         1.0 liter


Borax is used to make the pH of D-76 alkaline.
sodium sulfite is used to make the pH of lc-1 somewhat acidic.

Dave has lc-1 made from two solutions.  Mixing A&B&water in different
proportions changes the pH of the developer which changes the "contrast"
of the developed negative.

Developers need an alkaline environment to work well.  Dave made LC-1
somewhat acidic to retard the activity of the develop in order to make it
a very slow acting low contrast developer.

I am wondering if it is possible to add something to D-76 to make it more
acidic and thus make it act more like LC-1.  Changing the pH of LC-1
doesn't change its ability to develop negatives.

Would it be possible to add an appropriate volume of, acetic
acid - stop bath, or sodium bisulfite, to D-76 to lower its pH and have it
work like LC-1?

I believe borax acts as a buffer and tends to minimize pH changes within a
certain range.

Would the addition of a small volume stop bath alter anything but the pH?
If not could this be used to convert d-76 to somehting like lc-1?
Everyone should be able to get stop-bath and D-76!

If this were possible people without access to metol could make their own
low-contrast version of d-76.

I have dim memories of an equation used to calculate the pH of solutions.
Maybe this could be used to figure out the pH of a particular LC-1 mix,
and then used to calculate how much stop bath would have to added to a
particluar volume of D-76?

Does anyone have an idea of whether or not this would work?

Gord



---------------------------------------------------------
Gordon J. Holtslander		Dept. of Biology
holtsg@duke.usask.ca		112 Science Place
http://duke.usask.ca/~holtsg	University of Saskatchewan
Tel (306) 966-4433		Saskatoon, Saskatchewan
Fax (306) 966-4461		Canada  S7N 5E2
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