Re: haunted GUM (related to judy's favourite pet peeve: the pigmentratio test)

[Paul Viapiano <viapiano@pacbell.net>]

phritz...

The inversion you're seeing is weird, a positive of that chart will always 
print with black text on white.

But you're printing the positive, right...you never inverted it to print?

NOw, there's inversion that K speaks of on her site but that is not TOTAL 
inversion, just a reversal of the high tones usually because of gum/pigment 
ratio. I've experienced this once on a test strip. I added gum and it was 
fine.

But  a TOTAL reversal as you are claiming...well, I've never heard of that 
at all.

Are you absolutely positive (no pun intended) that you exposed the correct 
digital charts?

p




----- Original Message ----- 
From: "phritz phantom" <phritz-phantom@web.de>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, October 06, 2009 10:10 AM
Subject: Re: haunted GUM (related to judy's favourite pet peeve: the pigment 
ratio test)


> dear katharine,
> yes, this is my main source of confusion. i was experimenting with higher 
> pigment loads. i made three layers of yellows and reds (for the 
> highlights) and then wanted to add the shadows. i mixed up a stong 
> emulsion (the 2.5gr blue black one) and thought that the worst thing to 
> happen is that the layer just washes off and i can do it again. i tried 
> the heavy load to check the limits of the process, to see how far i can go 
> with the pigment concentration. the layer not dissolving at all, that i 
> was not prepared for.
> i did this twice (i saved the excess emulsion from the first coating). at 
> first a 2:30 exposure and a 2-3h development, the last hour in hot water 
> (appr. 40°c/ 100°f), then i had enough and brushed it all off. dried 
> overnight and painted on the same emulsion the next day. this time with 
> only 1min exposure. same result.  no flaking, the emulsion did not move at 
> all. also when forcing the development with a brush, i did not see the 
> usual high-contrast image (the highlights coming off before the shadows 
> which got lots of light), it just came off all at once.
>
> then i coated the test sheet with the 1.2gr of iron oxide. and saw the 
> pigment in the unexposed area behave the same way as the emulsions before. 
> this makes me assume that there is some kind of connection. i just don't 
> know which one.
> ....
> i just wanted to type that the test sheets "printed with a lot of stain, 
> but in a way like i expected them to", then i started wondering why the 
> "stain" is happening in the areas that should be pitch-black, because they 
> are in the clear areas of the transparency. now, i went and had another 
> look at those and saw that they are completely INVERSED. i printed 
> negatives from a negative (i did NOT forget to inverse the scale in 
> photoshop).
> here are the scans:
> http://i31.photobucket.com/albums/c367/phritz/threestrips.jpg
>
> the one on the left and the one in the middle got 1min exposure (all three 
> scales the same) from my sunlamp. the one on the right got 10min of desk 
> lamp.
>
> here's the proof for the inversion:
> http://i31.photobucket.com/albums/c367/phritz/P1010035.jpg
>
> i think i'm losing my marbles here... we'll see how the test strips from 
> today will print.
>
> phritz
>
>
> Katharine Thayer schrieb:
> > phritz, you've got the right idea about different pigments requiring 
> > different amounts to achieve a color-saturated layer; pigments vary 
> > widely in pigment strength, as you're learning.    Most earth pigments, 
> > like your burnt siena, are quite weak as pigments go, so it's not 
> > surprising that you don't get an opaque coating with a fair amount of 
> > burnt siena (also, some burnt sienas are quite transparent).
> >
> > The main comment I want to make in a hurry is that underexposure is not 
> > likely your problem.  If your strip were "severely underexposed" the gum 
> > coating would  dissolve into the water within a few minutes, leaving you 
> > a piece of white paper to dry and try again.  Since you have it even 
> > where there's no exposure, that suggests stain rather than overexposure 
> > as the source of the problem.  Also, where you've wiped off the bulk of 
> > the pigment layer on the area that received no exposure,  there's still 
> > significant stain left (that grainy deposit, that's pigment stain.)  Too 
> > much pigment, it looks almost certainly.
> >
> > But there are a couple of things that don't make sense to me, so maybe a 
> > clarification:  I'm reading that this is one part of a sheet you coated 
> > and  tore into three pieces, and the other two pieces printed fine? 
> > Could we see those?  It doesn't make sense that with two parts of the 
> > same coating on the same paper it printed fine and with one part there 
> > was serious stain, so maybe I'm not understanding your 
> > description/example/question.
> >
> > But definitely not underexposed, if you've got heavy tone like that that 
> > won't go away in 20 minutes of development.
> >
> > There's an example with lamp black on my pigment stain page that looks a 
> > lot like yours, down towards the bottom of the page, compared to how it 
> > prints with half the amount of pigment. (third visual down on the page).
> >
> > http://www.pacifier.com/~kthayer/html/stain.html
> >
> > Hope any of that is helpful
> > Katharine
> >
> >
> >
> > On Oct 5, 2009, at 4:28 PM, phritz phantom wrote:
> >
> > > hi all,
> > >
> > > my gum is acting strange again. the only reason i can think of is an 
> > > increased pigment load.
> > > my standard pigment is lamp black, which is a very strong pigment. 0.5gr 
> > > are enough for a very thick and opaque layer (before exposure). since i 
> > > was used to this strong pigment, i was generally using too little 
> > > pigment for all the other colors, resulting in very thin layers. so, i 
> > > made a comparison sheet with dabs of all the different pigments (all are 
> > > powder pigments) in various strengths. i was quite surprised to see that 
> > > for example 2gr (+5ml gum + 5ml saturated pot-di) of my burnt terra di 
> > > siena produces a coating that is neither thick, nor opaque.
> > >
> > > at first everything went fine, then suddenly a very thick blue black 
> > > coating (1,5gr iron oxide black + 1gr phthalo blue +5ml gum + 5ml 
> > > pot-di) didn't come off at all during development. ok, i thought the 
> > > reason was that i increased the exposure time as well to compensate for 
> > > the bigger amount of pigment. later: the same with a short exposure of 1 
> > > minute. the next day: again, with a layer with 2gr of burnt siena.
> > >
> > > it was time to search for errors. i coated a sheet with 1,2gr of iron 
> > > oxide black (not my favourite pigment), again with 5ml gum + 5ml pot-di, 
> > > ripped it in three parts and made a comparison of the two different 
> > > sheets of glass i use as printing frames and put the  third  one for 
> > > 10min under the desk lamp that i often use during registration and such. 
> > > the first two printed fine and pretty much the same. but with the third 
> > > one, i noticed something strange. not only that there seems to be some 
> > > uv present in the light of the desk lamp, but also: i left part of the 
> > > sheet covered and it received zero exposure. and this part stayed 
> > > completely black, not a whiff of pigment came off in the appr. 20min of 
> > > development.
> > >
> > > here's a scan of the test strip:
> > > http://i31.photobucket.com/albums/c367/phritz/teststrip.jpg
> > >
> > > the part on top with the white stripe received ZERO exposure. i 
> > > scratched off a little bit to show that the pigment is wet and soaked. 
> > > it can be removed, it just doesn't want to come off on its own (nor did 
> > > i have any success with brushing or sprinkling of water, only nothing or 
> > > everything comes off)
> > > i'm sure this is somehow related to my problems. i'm just getting too 
> > > confused here. it probably means that my images were severely 
> > > underexposed. i did extensive testing for negative colors lately and 
> > > determined with a step wedge (unfortunately not a stouffer one) that my 
> > > minimum print time is 50seconds. i printed the thick layers with up to 
> > > 2:30min. still nothing.
> > >
> > > (sorry for my total inability to write succinctly in english... my 
> > > apologies)
> > > can anyone put some sense in this? i'm completely lost. any tips, except 
> > > trying even longer exposures?
> > > thanks,
> > > phritz