Re: gravure plates under vacuum

[SusanV <susanvoss3@gmail.com>]

Hey Jon... yes you got it correct.  Nothin touched the positive.  only
vacuum pressure held it to the plate.  I just posted a scan of the
print to my blog.  I'm thrilled with the sharpness and detail.  I
think for my work, this is going to work out great.

Now if I can just find some more midtones :o)  This particular print
IS dark and without a lot of greys though, so it's not the best test
for that.  I have to spend some time next with my printer and get rid
of those horizontal lines.  It doesn't always do it though, so I think
I just have to methodically find the right combination of resolution,
etc.  Also going to run the alignment thing on the pictorico, etc.

and yes... I'm a closet engineer for sure.  and carpenter.  and electrician.

:o)
susan

updated today... www.susanvossgravures.blogspot.com



On 3/4/07, Jon Lybrook <jon@terabear.com> wrote:
> I think all great artists are closet engineers as well.  You certainly
> qualify as both Susan!
>
> Let me see if I understand correctly.  You put masonite on the bed and a
> piece of burnished foamcore with a window on top of that, and then put
> the film and plate in the window in the foamcore.   This means there was
> nothing physically touching the top of the transparency to hold it to
> the plate and that the only thing keeping it there was gravity and
> whatever the vacuum pressure was able to do?
>
> How large was the plate and film you used?  5x5 as well?
>
> Can't wait to see the results of your experiment!  Wonder if it will
> work with Krene...though I'd hate to have to reinstall the glass into
> the vacuum frame.
>
> Jon
>
> SusanV wrote:
> > Hi ya'll,
> >
> > Jon, I did the experiment you suggested with a piece of virgin km73
> > and pictorico ohp under vacuum.  I watched as the vacuum pulldown
> > advanced, right along with the splotchy look of the contact between
> > plate and film.  dark areas where the film contacted (maybe too
> > tightly?), and lighter elsewhere.  I came to realize that the darker
> > areas seemed related to the plate and film being drawn up against the
> > glass of my exposure unit very tightly.  (Jon, this would go along
> > with what you've said about too much vacuum being a problem)
> >
> > I wondered if the lighter areas were indeed close enough for a sharp
> > exposure.  I couldn't stop the darker splotches from happening even by
> > using as little as 5"mercury pressure...   the moment the sandwich
> > raised up and touched the glass, the splotches appeared.
> >
> > At this point I should maybe describe my vacuum/exposure bed because
> > I'm not sure if          they all work this way... The actual pebbled
> > surface bed of the frame is rather thin and flexible, and during
> > vacuum drawdown it rises up, lifting the plate and film up to come in
> > firm contact with the glass, which rests on a raised rubber gasket
> > around the perimeter of the bed..
> >
> > So... how to draw a vacuum for close contact, but not caused the
> > sandwich to  be pressed together physically by contacting the glass.
> >
> > I placed a piece of masonite, maybe 11x14" on the vacuum bed.  Then I
> > cut a 5x5" window in a similar sized piece of foamcore, and placed
> > that on top of the masonite.  (To allow air to escape I used a
> > burnisher to draw some deep indentations in the underside of the
> > foamcore, radiating out from the window to the outside edges.)  I then
> > put the plate and ohp positive in the window (no powder), and turned
> > on the vacuum.  The vacuum drew down to 22" pressure, and the window
> > and masonite under it didn't allow the plate to rise up to the
> > glass!!!  The film maintained a totally measle free, even, light
> > tone... even after an extended drawdown time (like 3 minutes or so).
> >
> > I exposed the plate, developed, etc... and when I printed it, there
> > were no measles.  What's more... there is very fine detail in this
> > image, and it was ALL there, crisp and sharp as can be!  There was
> > definitely close enough contact with the film without it being
> > physically pressed together.  The vacuum was enough.
> >
> > So for me, I think this is going to be my solution to the measles.
> >
> > I'll post this test print to my blog later, including some closeups of
> > the sharpness of the detail.
> >
> > susan
> >
> >
> > susan
> > gravure blog at www.susanvossgravures.blogspot.com
> > website www.dalyvoss.com
> >
> >
--
susan
gravure blog at www.susanvossgravures.blogspot.com
website www.dalyvoss.com