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Another approach to bleaching.

At the AIC conference in San Diego in 1997 Margot McFarland gave a paper on
the intriguing use of cellulose gels- mainly methyl cellulose, into which
was mixed a small amount of hydrogen peroxide which had been buffered with
ammonia.  This mixture allowed to her to apply the gel directly onto lead
white pencil drawings that had darkened, turning lead sulphite into sulphate
black.  The buffered peroxide solution converts the lead back to a white
color by supplying extra oxygen molecules that turn the lead sulphate into
sulphite.  Oddly enough, this is a method that is not too disimilar from the
way a dentist whitens teeth, and Ms. McFarland did some of her research at
the American Dental Association Library in Chicago.

Without getting into the intricacies of converting darkened lead in art on
paper, it occurs to me that a similar mixture could be devised that would
allow a medium with some consistency.  It could be made more like an ink,
that would flow well in a pen, and use a much smaller amount of bleaching
agent.   An oxidizing bleach like hydrogen peroxide still damages cellulose,
but can be better controlled with a buffer for a gentler lightening action.
Unlike hypochlorite bleaching, it doesn't seem to need as lengthy a rinse
afterwards.  As the peroxide breaks down, it's residue is water, leaving no
chlorine residue that stays active as when using hypochlorites. You can also
further buffer it when finished.

I also wonder about combining this method with light bleaching- place the
paper with the wet gel medium out in the bright sun for a bit, and watch
what happens.

For a calligraphy project, you might try 1 % peroxide, 1 % ammonia in  3-5 %
methyl cell.  It's best to measure the ph if you can...

theoretically, it's almost like a reverse invisble ink...or rather an
"invisibling ink"

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