There is a valid argument for using a "seasoned" MQ developer like D-76. The hydroquinone monosulphonate ion formed from the oxidation of hydroquinone is a soft-working developing agent. It slowly builds up in a replenished system and changes its character. However, there is no hydroquinone in Xtol and nothing similar is produced by the oxidation of ascorbic acid. All its oxidation products have no developer activity. So any benefit of a seasoned Xtol solution is really unsupported and somewhat illusionary in my estimation. It is illusionary in that it can only be done with reuse and not by any other means. Want to experience seasoned Xtol just add some potassium bromide. With this particular developer that is the only effective thing which changes.
Well what about the Dimezone? It is either regenerated by the ascorbate or if not its oxidation products have no developing activity. Self replenished Xtol changes rather slowly because a rather large amount of fresh developer must continually be added. This is usually not the case with other developers like D-76 or Autophen where a small amount of a special replenisher is added. It is instructive to look at the differences between D-76 and D-76R. D-76R contains no bromide and increased amounts of Metol and hydroquinone to replace that used up for each roll. The amounts arrived at were only found after long and exhaustive tests.
Well what about the Dimezone? It is either regenerated by the ascorbate or if not its oxidation products have no developing activity. Self replenished Xtol changes rather slowly because a rather large amount of fresh developer must continually be added. This is usually not the case with other developers like D-76 or Autophen where a small amount of a special replenisher is added. It is instructive to look at the differences between D-76 and D-76R. D-76R contains no bromide and increased amounts of Metol and hydroquinone to replace that used up for each roll. The amounts arrived at were only found after long and exhaustive tests.
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