Re: Diafine HELP

Steve Avery (stevea@sedal.usyd.edu.AU)
Thu, 24 Oct 1996 16:46:52 +1000

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Kevin et al:

One of the big problems with phenidone - and, hence, Diafine - is that it
is very hard to get to dissolve. If you mix diafine according to the
instructions on the package, chances are that very little phenidone will
actually go into the solution. You can tell if you use one of those
filtering funnels. If a fine white sludge remains in the filter, it isn't
in the solution. There is such a small amount of phenidone used in the
solution that it is very easy to overlook. I used to wonder what that
stuff was and why the developer didn't work very well, until I put 2 & 2
together.

My books are all in boxes right now, so I can't check, but Dignan suggests
(if I recall correctly) that phenidone dissolves best alone in water that
already contains a small amount of metabisulphite. It won't dissolve in
sulphite. Maybe someone else has the book handy.

In the rough and tumble of the lab, I used to just dissolve the phenidone
directly in water heated to boiling. Unorthodox, but it worked fine with
no adverse affects that I noticed. In fact, the quality of the negatives
was so much better - "night and day".

What I don't get is why people keep buying the stuff since probably they
don't know this and are using the developer without the component that
really makes it special. Why don't they label it so it works for the
customer?

I hope this helps you.

Larry Bullis