U of S | Mailing List Archive | alt-photo-process-l | RE: Miracle size for gum

RE: Miracle size for gum



I think it’s a good idea Judy does try what PVA she has at home as I will too. I have some Unibond, (http://www.makingdiyeasier.co.uk/unibond/pva.html) which is PVAc used in the building industry. I’ll try it when I get some time in a week or so. Gamblin PVA can’t possibly be the only PVAc in the world that works, surely.



BTW both PVAL and PVAc are ‘glues’ among other things.




From: Paul Viapiano [mailto:viapiano@pacbell.net]
Sent: 12 October 2009 06:08
To: alt-photo-process-l@usask.ca
Subject: Re: Miracle size for gum




Gamblin PVA Size is what you want...go to Utrecht...don't bother with anything else.


I do have PVA adhesive here at home and I use it for bookbinding. It's a glue...







----- Original Message -----

From: "Christina Z. Anderson" <zphoto@montana.net>

Sent: Sunday, October 11, 2009 6:40 PM

Subject: Re: Miracle size for gum


> ----- Original Message -----
> From: "Judy Seigel" <
>> Sometimes I have trouble staying out of an argument, because who doesn't
>> love a good argument? Research shows, moreover, that an argument about gum
>> firms the skin and makes the hormones flow, while discouraging outsiders
>> from attempts to muscle in on the process. But the gum argument (or
>> "discussion") I'm staying out of now is because I don't know what the hell
>> folks are talking about & decline to expose my ignorance.
> Judy,
> I hear ya, I hear ya...I agree in that testing and arguing about gum doesn't
> get gum printers or gum prints made.  The proof in the validity of gum
> testing comes in the work produced, IMHO.  Now, that will open another can
> of worms--what constitutes a "good" gum print and I daren't touch that with
> a ten foot pole. But there are a lot of excellent gummists who never pick up
> a step wedge. They just make prints.
> I find it extremely useful that when we discuss things as tonal range,
> miracle size, more or less dichromate, more or less exposure, etc. we find a
> way to talk apples to apples in gum, and that is where the lowly step wedge
> comes into play for me--scientific or not, used and discussed correctly or
> not (thanks, Etienne).
> Thus when a statement is made that such and such produces a longer tonal
> range, I take it to mean that the maximum "black" for that color pigment has
> been reached (obviously not black as in a glossy silver gelatin) as well as
> paper white has been achieved, and those steps in between can be counted and
> compared to get somewhat close to apples to apples.  Either the step wedge
> shows just a few steps, or lots of steps. And each step on the step wedge,
> being film, is a difference of 1/3 stop or 1/2 stop that corresponds to
> increasing or decreasing hardening of gum, whether that hardening equates or
> not to a measurable log of density.
> When gum gets a bad rap as being a "two stop process" which, I assume, the
> writer meant there were only 4 **steps** of color on the step wedge or 6 on
> a 31 step (writer is well known, and certainly gum has a reputation of being
> a short scale process), then it is important to discuss what kind of tonal
> range people who gum print frequently are getting.  I personally don't find
> gum THAT short scale of a process.  Certainly not as tonally long as
> platinum but long enough.
> But as has been found in this discussion, as usual anything gum, the
> parameters of the testing is different from gummist to gummist and therefore
> no longer compares apples to apples anyway.  And then we get into arguing
> over how many angels dance on the head of a pin.
> And then it's interesting to see your advice come back to you--or not.
> Seems to me a while back on this list I dared to suggest that past a certain
> point more dichromate wasn't necessary--it didn't decrease exposure enough
> to warrant the extra amount and I settle now on an easy to measure 15% am di
> (used to use 7.5%, one list member only uses 2.5% and her exposures are not
> lengthy).  That by a step wedge.  Wow did I get creamed in that discussion.
> Seems I also mentioned that using EQUAL strengths of ammonium, sodium, and
> potassium dichromate had different speeds--ammonium being the fastest, and
> for all the solubility that sodium has, it doesn't have much oomph--more
> like potassium at the same strength (used 10% for all).  That I found by a
> step wedge.  I know at least Sandy King corroborated and even gave a
> percentage comparison between am and pot di. Oh, and Kosar as well...but
> man, the first time I mentioned Kosar I was creamed.
> So even though using a step wedge on a process that really isn't
> photographic in a sense (just photosensitive) and talking about it in
> photographic terms, that step wedge sure is a handy little thing...
> OH, and having been cleaning out my dimroom all day, I finally found my
> motherlode of step wedges.  I had lost them I thought permanently, and
> ordered 3 more 4x5s and 1 8x10, and NOW I have a passelode of the things,
> heheheheh.  I just love this cleaning thing. For some reason I had put them
> under a towel on top of which I let gum prints dry before exposure.
> Back to size, Marek, I am going to run right out and buy that miracle size,
> lemmetellya.  If I could find a nontoxic size that also printed a LONG TONAL
> RANGE (gasp) I will personally come down to TX and kiss your cheeks!! And
> Jeremy Moore, that video thing is a great idea to do for the list! Good
> discussion...
> Chris
> __________________
> Christina Z. Anderson

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