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Saturday, June 8, 2013

Trust me, I am working hard...

Note: I made a mistake in the parameter used for Hydroquinone. Instead 1,28 it is 1,82 what is different. Although this is merely speculative, every MQ developer will develop with any amount or proportion and have their specific application. The number of recipes is endless, thanks God.

Aplying the equalities about which I spoke in the last article, I could produce following chart for general purpose MQ developers. Each of these developers will have a different behavior, from high to low contrast and the grain will be finer as the amount of sulfite is more and more greater than carbonate.


«Corrected data»

The data above can be better understood in the logarithmic graphic below:

«Corrected graphic»


It has a certain logic, when you think that developers containing only carbonate as alkali have about 50 g/Liter and developers containing only Sulfite have 100 g/ L. At the ends of the curves there is a discontinuity, we may have developers with only metol and sulfite and developers with hydroquinone only but with both sulfite and carbonate in almost identical amounts:

Examples:

1 Liter "Wall's Normal Hydroquinone", a lithographic developer, work solution:
50 g Sodium Sulfite
10g Hydroquinone
60 g Potassium Carbonate (or Sodium and the amount could be also 50g anhidrous)


1 Liter D23 of Kodak, a fine grain low contrast developer:

100 g Sodium Sulfite
7,5 g Metol

Disclaimer: The equations I proposed don't fit all and every general purpose developer, it is only an orientation. You may compose your developer with any amounts of the main substances, you may adapt the reasonings to other developing agents if you know the equivalence (Phenidone acts like metol but is 10 times stronger). Important is to know then what you get, how long the developer takes to develop and so on.

Final note: The equations used are now a little different, I introduced another condition, the sum of sulfite and carbonate should be constant:

Hydroquinone = 1,82*Metol
Sodium Carbonate = 46 - 6*Metol
Sodium Sulfite = 100 - Sodium Carbonate

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