Re: Dry plate ferrotypes?

From: "Best, Dianne" <dbest@hydro.mb.ca>
Subject: FW: Dry plate ferrotypes?
Date: Thu, 16 Jun 2005 11:16:38 -0500

> I am 90% sure that these were dry plate. Whatever method the
> photographer used to spread the emulsion left the same kind of
> patterns that my brushed-on emulsion does - not filled out right to
> the edges, somewhat thicker toward one edge of the plate, somewhat
> scalloped or irregular along the edge of the emulsion. There is no
> hint of any kind of a wash outside of the coated areas. The time
> period of 1880s also fits with the early days of the dry plate
> process. Maybe I am wrong but I don't suspect so.

I agree by 1880 collodion was mostly replaced with silver gelatin, at
least for camera negatives.

Do you think what you saw was based on lantern slides? There were some
very fine grained iodobromide emulsions that are made for positive
applications like slides. They give Dmax of about 3 and gamma up to 3,
though speed is very low (maybe 10-50 times slower than most enlarging
papers today). Those emulsions were made with the goal to achieve high
gamma and very low fog. They were often processed in MQ carbonate
developers or pyrogallol carbonate developers.

--
Ryuji Suzuki
"Well, believing is all right, just don't let the wrong people know
what it's all about." (Bob Dylan, Need a Woman, 1982)