Re: Newton Squashed Under Pressure (photogravures)

[SusanV <susanvoss3@gmail.com>]

Hey Jon,

The reason I'm so sure about this is that the other day when drying a
plate I noticed a flaw, so I looked at the hardened plate with a 10x
loop under really bright light, and there they were... the same little
mottled areas I see on my prints.  They were on the plate, no doubt.
They are actually little squiggly lines.  The Newton rings aren't
round rings at all... they are irregular in shape and as they all
bunch together as they shrink under vacuum they form those little ...
squiggles.

As for why I could use less pressure... I'm getting good results with
what I consider moderate pressure for intaglio... except for the
darned squiggles.  I changed to harder blankets and cranked the press
down tighter, and it got rid of the squiggles.  It's just pressing so
hard that it's eliminating them in the press.  Without the marks on
the plate to begin with, I can go back to less pressure and my regular
blanket setup.

hey, maybe I'm nuts and will end up eating my words... wouldn't be the
first time :oP

time will tell as I work this out.

susan

On 4/11/07, Jon Lybrook <jon@terabear.com> wrote:
> SusanV wrote:
> > Hi all,
> >
> > After a long time of troubleshooting this problem I've had of tiny
> > little irregularities of tone, not measles, but speckles... This is my
> > current thinking.  They ARE caused by Newton's rings between both the
> > imagesetter film and Pictorico OHP and the glass of my vacuum table.
> > It's been suggested it was caused by not using enough pressure when
> > printing (intaglio), but what I have found is that additional pressure
> > does eliminates the speckles ***which have been caused by newton's
> > rings****.
> >
> > Furthermore, the reason my speckles are tiny and numerous, has to do
> > with vacuum pressure of 22".  The more pressure I use, the smaller the
> > rings become, but they also become more numerous.
> Tiny speckles?  Newton rings generally look like tiny gray-black
> droplets or spots of varying sizes on the print from my experience.  Not
> speckles.  Could you please post an example or two and indicate the
> problem areas?
> >
> > My goal now is to settle on one of the several solutions to Newton's
> > rings (clear spray on the back of the inkjet positive, frosted mylar,
> > Kreene plastic, etc ), so that I can use less pressure when printing,
> > reducing wear and tear on my press over time (not to mention my biceps
> > are beginning to develop to Popeye proportions :^O )
>
> I'm confused.  Why would solving newton ring problems allow you to use
> less pressure on the press?  Polymer photogravure always requires alot
> of pressure to get a crisp impression.  No way around that.
>
> The standard, coarser aquatint screen results in speckles in the final
> print, which is why I don't use it...is that what you're seeing?
>
> Thanks,
> Jon
--
susan
gravure blog at www.susanvossgravures.blogspot.com
website www.dalyvoss.com