Phenidone substitution

[dpodeath]

The Darkroom Cook Book says you can substitute metol with phenidone at around 10% of the weight of phenidone. It doesnt mention if you can substitute phenidone with metol but if you did would just multiply the weight of phenidone by 10?

i want to try the Mytol formula #26

Sodium Sulfite 85g
Sodium Metaborate 4g
Sodium Ascorbate 12g
Phenidone 0.15g
Sodium Metabisulfite 3g

The book also says i can substitute sodium ascorbate with ascorbic acid. "ten grams of sodium ascorbate can be substituted with 8.89 grams of ascorbic acid" so the formula is ten times "x" equals 8.89, when you solve for "x" it is .889, so 12 times .889 equals 10.668.

So then would i be right in thinking i could use this formula.

Sodium Sulfite 85g
Sodium Metaborate 4g
Ascorbic Acid 10.6g
Metol 1.5g
Sodium Metabisulfite 3g

would i also need to change the sodium sulfite because of the acidity of the ascorbic acid?

-charlie

 

[nworth]

The answer is usually. The results may not be exactly equivalent, but you will usually get a usable developer. Exceptions include specialty phenidone only developers, like POTA.

 

[Alan Johnson]

There are slight variations in the formula of Mytol, #26 in the Darkroom Cookbook p218 appears to be the latest.
The method of making sodium ascorbate from ascorbic acid and sodium bicarbonate is described here:
www.photosensitive.ca/wp/easy-film-developers

 

[gainer]

The Darkroom Cook Book says you can substitute metol with phenidone at around 10% of the weight of phenidone. It doesnt mention if you can substitute phenidone with metol but if you did would just multiply the weight of phenidone by 10?

i want to try the Mytol formula #26

Sodium Sulfite 85g
Sodium Metaborate 4g
Sodium Ascorbate 12g
Phenidone 0.15g
Sodium Metabisulfite 3g

The book also says i can substitute sodium ascorbate with ascorbic acid. "ten grams of sodium ascorbate can be substituted with 8.89 grams of ascorbic acid" so the formula is ten times "x" equals 8.89, when you solve for "x" it is .889, so 12 times .889 equals 10.668.

So then would i be right in thinking i could use this formula.

Sodium Sulfite 85g
Sodium Metaborate 4g
Ascorbic Acid 10.6g
Metol 1.5g
Sodium Metabisulfite 3g

would i also need to change the sodium sulfite because of the acidity of the ascorbic acid?

-charlie

The direct substitution of ascorbic acid for the ascorbate would drastically change the pH of the solution. Make a solution of the 10.6 grams ascorbic acid in about 100 ml water and add slowly 4.5 grams sodium bicarbonate (baking soda). It will produce the ascorbate along with much effervescence. When that subsides, add the other ingredients of the developer and briing the volume up tp 1 liter.

 

[Alan Johnson]

Also,I don't think metol will dissolve in strong sulfite solution and I believe it is the usual method to add a pinch of sulfite ,then the metol ,then the bulk of the sulfite.

 

[gainer]

Also,I don't think metol will dissolve in strong sulfite solution and I believe it is the usual method to add a pinch of sulfite ,then the metol ,then the bulk of the sulfite.

Yes. In fact, a solution of Metol without the sulfite is quite acidic, and no harm will be done by dissolving all the Metol in plain water. For example, the oldest instructions I have seen for preparing D-76 (although it was not yet named as such) were in the book "Principles of Optics" by Hardy & Perrin, where it was stated that the Metol should be dissolved first in a small volume of water, then about 1/4 of the sulfite separately in hot water.

 

[H2O]

...add slowly 4.5 grams sodium bicarbonate...

I thing 5.1 g

And description here:
http://www.photosensitive.ca/wp/easy-film-developers
...dissolving 88.9 g sodium bicarbonate and 42.5 g ascorbic acid...

It should be
... dissolving 42.5 g sodium bicarbonate and 88.9 g ascorbic acid

 

[Alan Johnson]

Thanks for that, H2O,good job someone is awake, I agree with your figures.
C6H8O6...............+..NaHCO3..........->....C6H7NaO6...+H2O....+CO2
Ascorbic Acid....Sodium Bicarbonate..->..Sodium Ascorbate....
176.1g.....................84g...............->.....198.1g
10.7g.......................5.1g..............->.....12g

 

[gainer]

Somehow my 82 years of age made me use the molecular weight of the ascorbate instead of the acid in calculating the weight of bicarb. 5.1 is correct.

 

[dpodeath]

Somehow my 82 years of age made me use the molecular weight of the ascorbate instead of the acid in calculating the weight of bicarb. 5.1 is correct.

thanx everyone for all your help. i mainly wanted to use the developer to push 400 speed films to 1600 or 3200 at 1:1 ratio for concert photography.

-charlie

 

[gainer]

You may be disappointed. OTOH, concerts in my experience average to low values of light, so if you use average meter readings, you may only be using the film at its nominal speed by setting the meter at 1600.

 

[gainer]

Saturated borax solutions

This chart of saturated borax vs temperature should be of help if I can get it to come through.