Phenidone substitute

[archer]

Is there any reason that Dimezone S should not be substituted for Phenidone in formulas that call for Phenidone and are the two chemicals substituted equally weight for weight?
Denise Libby

 

[Ian Grant]

You can use Dimezone-S, the substitution is 1.27x the amount of Phenidone.

Some of the Ilford PQ liquid developers now use Dimezone-S.

Ian

 

[monodave]

All of the Ilford liquid developers that used to contain Phenidone have contained Dimezone S since the early 1990's. PQU was the last to change in about 1993. The replacements were made to give much longer shelf lives.

 

[Gerald C Koch]

Phenidone hydrolyses in alkaline solution. The higher the pH the greater the rate of hydrolysis. For Dimezone and Dimezone S the rate of hydrolysis is slower. Since the molecular weight of each is larger than that of phenidone more must be used to get the same activity. I have read one claim that says that the activity of the Dimezones are less than that for phenidone even when compensation is made for the differing MW's.