Re: Gum problem(s)

First about the claim that at $5 a pop photoflood is a bargain -- not, as
I recall, necessarily so. Isn't the photoflood rated for 25 hours? And
changes a lot over that time -- tho for gum, where development is an easy
variable, that's not so serious. Still -- if you want to go larger, you
need 3 or 4 photofloods, at least I did -- because edge falloff is
dramatic.

Flourescent bulb at about $12 apiece is rated for 9 to 12 thousand
(THOUSAND) hours.

But I doubt bulb is Yves main problem, I think that cockamamie mix
probably is.

First, that gum mix sounds much too thick. In the days when, younger &
foolisher, I mixed my own gum arabic, I found 1 to 3 gum to water was
quite thick. Then he's using dry pigment, which adds to thickness, but
seems not to have extra liquid to compensate. He can't spread the stuff,
let alone get that photoflood (never intended for UV exposure. Came into
use as I recall, when "straight" photographers began to switch to "alt"
because they had it on hand already for SG copy shots) through it. That
Katharine found it excellent right off is, I suspect, just kismet.

As I recall, Yves still hasn't noted the color. Pigments are VERY
different. I suspect he may have been falsely warned off bought paints --
those additives, et al, apply mainly to "student" or off brands. A good
brand (my choice at present is Daniel Smith, but Winsor Newton & others
are good alternatives, tho I'm no longer up on any but DS) will have a
better ratio of pigment, no fillers, and any "additives" innocuous for our
purposes. STill, EACH color in any brand is different. Dispersal agents
(deadly for our purposes) may be added to some, not others, for example.

On Fri, 18 Nov 2005, Yves Gauvreau wrote:
> No wonder why I get lousy result. but I understand my biggest problem for
> the moment could be help in large part with sizing the paper. Of course a
> proper layer would help as well.

I don't recall the paper you're using, Yves -- but if other things are OK,
you should get a decent step wedge print even with NO sizing, in fact it's
often better -- and remember, that will change anyway with later coats,
which is what the sizing is for (to coat the fibers for after your first
coat has washed top finish away and/or raised the nap of the paper).

> I can't help myself thinking then why nobody is using a rotary table to coat
> the paper. This method allows uniform and thin coating of surfaces just by
> controling the RPM.

You don't need a rotary, another piece of equipment to torment you. You
need a mix that is *at most* no thicker than light cream. Then (I don't
recall how you're spreading it) but the best way IME is a foam brush
slightly dampened with distilled, well soaked in emulsion,which is freely
& quickly spread on any which way, then whisked smooth with a DRY hake
brush.

> I guess I'll have to get myself a scale. Formaldehyde, hum! Ain't this stuff
> super toxic, I eard the fumes can kill you in the long run. I also see most

Aspirin can kill you in the long run, & the formaldehyde is used quite
weak. But it's HELL used in a closed space... the fumes are terrible. But
peeling an onion the fumes are also terrible, not sure there's a relation
to risk. Anyway, unless you can harden outdoors, for your own sense of
well being glyoxal (not as far as I know any riskier than formaldehyde,
I've been told less so) might be more comfortable. Or now folks on the
list are using glutaraldehyde. But again, the size is meaningful in
printing and later coats, but almost any paper will give you the info you
need with no added size when you're just trying to set up your basics.

> of you (gum printers) choose the stuff over anything else. I assume nothing
> else comes closes, I saw gloaxial or something sounding like that being used
> and what about ALUN or other tanning agent.
>
> I would have concern about using these kind of stuff about the effect they
> would have on the permanance of the work????

It's been said that the alum can hurt pigments, but I have no experience
with it. As far as I know, however, formaldehyde & company just link the
gelatin and then go home. No residual effect on the print.

>> Photoflo is a good idea when working with dry pigments. I use Agepon,
>> the Agfa equivalent, but any surfactant agent should help. Only I use
>> it in minimal quantities: just a very small drop which is enough to
>> break the superficial tension of the gum+dichromate mix. Perhaps
>> you are using too much Photoflo?

I'd still say limit the wild cards for first trials... IME photoflo is not
required... even if supposedly beneficial. Which is to say, if it's not
broke, don't fix it.

> Yes, It's quite possible I use to much. As I learn more and more of the
> inner working of the medium and process. My goal would be to find ways to
> minimize if not eliminate the use of additive except maybe for stuff that is
> well known ( and documented) to be helpful in the preservation or permanance
> of the work.

Yves, I guarantee, anything you do on a good paper with good pigments is
going to be more permanent than you want it to be.... at least more
permanent than most other photo media. Assuming your PIGMENT is archival
in the first place.

>> content for your needs, mostly between 10am and 3pm or so. But avoid
>> the direct sun!

Actually, in this season in Canada, I understand direct sun would be OK if
carefully timed. If there is any of course. I remember in early days of
list a woman in New England said in direct summer sun she exposed 30
seconds.

As for that comment about reading newspaper through the emulsion, I'm
almost certain Paul Anderson (!!!) said it some place or other, but as I
recall the first time I came across it was Demachy.

Judy
Received on Sat Nov 19 17:39:11 2005