Re: old cyanotype formulae

["alnovo@inwind.it" <alnovo@inwind.it>]

> The history of cyanotype, it seems, is long and complex. Herschel is
> supposed to have suggested the process around 1850 but the processes he was
> refering to is a "positive" process i.e. opposite of what is being used
> today.

So, why Anna Atkins'  "British Algae: Cyanotype Impressions" (1843) is in negative?

Alberto

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