From: Ed Inman (email suppressed)
Date: Fri Mar 24 2006 - 16:47:32 PST
R-9 orange (dichromate) bleach retains a long shelf life fully mixed and
can be used multiple times, whereas the purple (permanganate) bleach is
usually recommended for use only one time then discarded.
The purple bleach is made as two separate solutions and mixed in equal
portions just before use.
Purple bleach also requires heavy, continuous agitation, so it is not
recommended for a rewind tank.
A conventional sodium sulfite clearing bath may be used to clear the stain
from either bleach.
If you want to make the purple bleach use this formula:
Solution A:
Water: 500 ml
Potassium Permanganate: 2 g
Solution B
Water: 490 ml
Sulfuric Acid (concentrated): 10 ml
(Add acid to water--never water to acid.)
Unmixed, these solutions will retain a long shelf life. Mix A & B 1:1 for
use and discard afterward.
Ed
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