Gum image has reversed

I'm new to the list and will apologize in advance for the barrage of
questions which I'm going to unleash over the next little while. My
frustration level is running quite high. However, for the moment, I will
try to limit myself to two main problems.

First, a little background. I dabbled in gum dichromate about 25+ years ago
and had some satisfactory results, but never really stayed with it. I
always wanted to get back into it and so, here I am. I still have the 1 lb.
jar of Potassium Dichromate I bought back then and still have some Gum
powder as well. Whether the age of my chemistry has any bearing on the
results I've experienced, I'm not sure. I really can't see how Pot Dichr
can "go bad" but, you never know.

My first question relates to the first usable print I've obtained after
many, many failures. I finally have something that suggests I have a chance
of success, but the print has reversed to negative. Can anyone explain
this? The detail is quite good, but I have a negative, not a positive.
Here are some details about my method:

> Lanaquarelle Medium Watercolour 140 lb. Paper, *not* sized
> Analogue 4x5 negative made in-camera on Tri-X film
> #2 blue photoflood light source about 25 inches from neg
> 20 minute exposure
> Emulsion made from 2.5 ml gum, 2.5 ml potassium dichromate solution and
> about 0.5 gm Daniel Smith Lamp Black pigment
> Still development for about 10 minutes brought up reasonable density -- my
> fear in letting in go on much longer was that I'd loose the entire image
> (just like the first dozen or so failures).

I realize that I should probably size the paper and that Lamp Black is not
the best starting pigment, but I was just trying to get myself into the ball
park on emulsion and exposure times. However, I'm stumped by the negative
product.

My second question relates to the type of gum arabic I should be using.
This success (if you can call a negative print a success) came after I
switched back to my old gum arabic powder (25+ years old). The gum was a
fine, white powder which I put into solution using the formula in "The
Keepers of Light" by William Crawford. My earlier failures had been done
using some Gum Arabic pre-mixed solution recently purchased from
Photographers Formulary. Using the pre-mix I got virtually no results --
anything I got was basically a "soot and chalk" type print where the shadows
went black and the highlights blew out. Nothing in between. No detail at
all.

Can anyone explain the lack of results with the pre-mix Gum Arabic? Should
I stick with the powdered form and mix it myself? The fact that I got
*some* results from the powder suggests to me that the pre-mix is somehow at
the root of my earlier problems where I got soot and chalk.

Many thanks in advance -- all advice gratefully received.

Bruce Pollock
Received on Sun Jan 8 22:40:13 2006