Re: gravure plates under vacuum
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- Subject: Re: gravure plates under vacuum
- From: SusanV <email@example.com>
- Date: Sun, 04 Mar 2007 10:58:35 -0500
- Comments: "alt-photo-process mailing list"
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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.
updated today... www.susanvossgravures.blogspot.com
On 3/4/07, Jon Lybrook <email@example.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.
> 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.
> gravure blog at www.susanvossgravures.blogspot.com
> website www.dalyvoss.com
gravure blog at www.susanvossgravures.blogspot.com