Re: Gum image has reversed

On Jan 9, 2006, at 6:48 PM, Bruce Pollock wrote:
>
> Humidity -- I live on the wet west coast of Canada where we have
> been experiencing what we call the "Pineapple Express" series of
> winter storms from Hawaii. I have no idea what the technical
> humidty level is at the moment, but let's just say that the birds
> are swimming, not flying.

  Hi, neighbor! How far west, by the way? Tofino? or mainland? At
any rate, your humidity should be the same as mine, like 99-100%,
which makes me wonder about your exposure times, although as I said,
I don't know how the blue bulbs compare. My platform is closer to the
bulb though, at 13".

> Other reasons for reversal of images -- I'm not sure whether this
> is relevent to printing with gum, but severe overexposure using
> silver materials will reverse the tonality. Ansel Adams
> demonstrated this with an image on one of his Basic Photo Series
> books. In a shot of the setting sun, the sun itself has turned
> black (in the positive final print) because of its severe
> overexposure in the negative. The rest of the image looks normal.

This isn't something I've seen in all my years of printing gum, so I
doubt it. (But then I only saw the tonal inversion thing for the
first time a few weeks ago.... ) But in my experience, gum just
doesn't work that way. Severe overexposure, especially with any light
source that generates heat, just ends up cooking the emulsion to a
fare-thee-well, in other words it will give you an overall heavy and
insoluble "fog" rather than an image of any kind, positive or negative.

Great tonal inversion, by the way. But definitely an issue of too
much pigment, IMO.

Well, the Pineapple special for tonight is roaring up an especially
huge storm, and I don't expect to have power much longer, so I'm
going to shut the computer off and find the candles instead of
reading the rest of this thread. Try to stay dry,
Katharine
Received on Tue Jan 10 02:25:19 2006