Digital BW, The Print

Gareth,

>Found this link yesterday of anyone if anyone is interested

>http://www.livick.com/method/inkjet/pg1.htm

Note that the test strips that show a positive effect from coating with UV
blocking sprays were in direct sun.

Sun has a lot of UV in it.  Glass filters out the shorter and most damaging
UV.  Acrylic filters out even more.  So, comparison of tests conducted in
direct sun will show much more effect from the UV filtering sprays than will
inside or fluorescent light tests.

For outside display, there seems little question that UV coatings are a very
good idea.  For inside display, I think there will be little difference
between coated and non-coated prints with respect to fading.  In my
fluorescent light testing I see little of no effect from most coatings.

I found that by the time I had the amount of UV coating that Golden (perhaps
the best supplier of acrylic coatings) recommended, the yellowing was
noticeable.  This might not be the case with all of these, but I decided,
given the lack of significant protective effects that I saw, that I'd be
better off just avoiding the UV absorbing additives.

Golden's technical person also noted that the solvent-based UV coatings are
much more effective than the water-borne UV coatings.

Paul
http://www.PaulRoark.com

__________________________________________________

 --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Robert Morrison
<rmorrison@p...> wrote:
> I haven't tested the hydrocote coated prints, but when I was
testing a
> variety of of different acrylic based coatings with piezo inks I
found
> that under dry south window testing the coating improved the fade
by up
> to 100%...so this is the opposite of Paul's results with the
Hydrocote.
>   Honestly I'm still a bit skeptical of the aliphatic polyurethanes
> being as good for paper coating as the acrylics...but this is not
based
> on actual comparative testing...just my knowledge of the respective
> chemistries.
>
> Robert
>
>
> On Saturday, August 9, 2003, at 06:35  PM, Paul Roark wrote:
>
> > jeffmoore17@c... wrote:
> >
> >> 1) Has anyone done any testing on the issue of whether or not
coating
> >> with a product such as Hydrocote Polyshield affects the archival
> >> properties of Piezography carbon prints?
> >
> > I've fade-tested coated v. non-coated prints.  I assume the MIS
and
> > Piezo
> > inks are about the same.  In general, the coated blacks faded a
bit
> > faster,
> > although I think that could well be due to the higher dmax
raising the
> > temperature (by absorbing more light).  The black ink in the test
was
> > the
> > MIS VM-K (probably the same as PiezoBW K).  The 50% patches were
> > generally
> > the same in terms of their fade rates.
> >
> > There was one other situation that seemed to accelerate the
coated
> > print
> > fading.  I tested one group under very high humidity conditions.
(The
> > test
> > light, etc. were right over a tray of water.)  The coated print
did
> > fade
> > faster.  The uncoated prints faded at essentially the same rate
as the
> > low-humidity tests.  I speculate that the difference could be
that the
> > hot
> > light artificially dries the un-coated prints, whereas the
coating
> > traps the
> > water around the pigments.
> >
> > In general, we've always been led to believe that high humidity
> > accelerates
> > fading, but this has never shown up in my tests except for the
coated
> > prints.  One of the criticisms of accelerated testing is that it
> > artificially dries the inks, with the result that the fade rate
is
> > reduced.
> >
> > So, I have 2 test results that seem to favor un-coated prints.
I'm
> > very
> > suspicious that both are more artifacts of the testing than
predictors
> > of
> > faster fading for PUR-coated prints.
> >
> >> 2) When coating Piezo prints with Hydrocote, after a good curing
> >> period, can these prints be drymounted, i.e., Seal tissue and
> >> drymount press?
> >
> > Yes, I've used Seal Colormount at 180 degrees f.  Be sure to use
fresh
> > release paper and wait the full 7-day curing period.  Also, with
> > trimming
> > the prints, a rotary trimmer might be a good idea.  I've noticed
a bit
> > of
> > edge roughness when trimming with a straight razor knife.
> >
> > As an aside, one of the PUR experts told me that heat accelerates
the
> > cross-linking and curing.  Heating the PUR soon after application
might
> > actually make for stronger coating -- bringing the
strength/extent of
> > cross-lining of the single-solution, water-borne products close
to the
> > industrial products.  (The adhesion of a water-borne PUR will
not,
> > however,
> > match the solvent-based products.)  This heating information
suggests
> > that
> > the use of a hair-drier might not only speed the drying and
curing,
> > but also
> > result in a stronger coating.
> >
> > Paul
> > http://www.PaulRoark.com
> >
> >
> >
> > Please visit the Group Homepage to check the Files, Bookmarks,
Polls
> > and other resources as they are often being updated. The page is
at:
> >
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> >



Please visit the Group Homepage to check the Files, Bookmarks, Polls and
other resources as they are often being updated. The page is at:

http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint

If you wish to receive no emails or just a daily digest, or you wish to
unsubscribe, please edit your Membership preferences by visiting this same
page.

Please follow these basic guidelines:
- Include your full name with your message.
- Include the address of your website, if you have one.
- As threads develop, trim off excess portions of earlier messages to keep
them short.
- As the topic of a thread changes remember to change the subject header.
- Good manners are required at all time. No personal attacks or flames
- Complete your Yahoo profile.
- Before posting a question, search the message archives and the various
resources on the homepage.




Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/