What is solarization?

[Sandy King <sanking@clemson.edu>]

I changed the format of my previous message to clarify who said what.


Judy Seigel wrote:

>
>
>What is the tipping point -- from "difference" to "gross reversal"? And
>if it isn't "solarization", what is it?
>
>For what it's worth, Cassell's defines "solarisation" as, "A term with
>many photographic meanings. It is synonymous with reversal (which see),
>and it is also applied to halation and bronzing."
>
>for Reversal: "REVERSAL OR SOLARISATION -- A phenomenon occurring as the
>result of extreme over-exposure, a positive instead of a negative image
>being produced on development. Abney has stated that preliminary exposure
>to diffused daylight, the use of a powerful developer, and the treatment
>of the plate with a solution of an oxidising agent before exposure,
>facilitate reversal; and, in his opinion it can only be produced when
>there is atmospheric oxidation. The addition of thiocarbamide to a
>well-restrained developer will produce reversal, especially if
>hydroquinone or eikonogen is used."


Then Sandy King said:

I understand the term solarization as Cassell defines it, as a 
reversal that occurs from extreme over-exposure. For example, if you 
take a picture on a sunny day that includes the sun you will under 
some conditions get a reversal of tones, that is, the bright sun 
becomes a black circle.

Over-exposure of 2-3 stops does not constitute extreme over-exposure, 
at least in my opinion.

I don't know what to call the phenomenon that I observed and 
described but it does not seem to fit with my understanding of 
solarization, which would include halation, bronzing and gross 
reversal of tones.

Sandy
--