Practice question · True or false
Metol and hydroquinone together develop faster than the sum of their separate rates.
Hints
- The effect has a name of its own in photographic chemistry.
- One agent regenerates the other as it works.
Show the answer
True
Why
True: this is superadditivity, and it is why almost every classic developer pairs two agents. The more active agent does the reducing and the second regenerates it in situ, so the pair sustains a rate that neither could hold alone. Phenidone and hydroquinone behave the same way.
Practise Developing the Negative
The app has 7 more questions on this lesson, and keeps your place in the course. Photography I is free to start.
More questions on Developing the Negative
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