Re: Epson Stylus Pro 9600 Extrachrome
Re: Epson Stylus Pro 9600 Extrachrome
- Subject: Re: Epson Stylus Pro 9600 Extrachrome
- From: neil_snape <email@hidden>
- Date: Fri, 12 Nov 2004 21:13:07 +0100
on 12/11/2004 19:27, Roger Breton wrote :
>
> HP 130 inks are light-fast dye-based inks.
Yes just dye.
>> If you
>> want it to be archival it must lay in the layer of polymer to protect it
>> against oxidation.
>
> OK. So an additive is 'added' in the ink. That you say changes the color
> property of the ink.
No. Glycol is a transport vehicle for the dyes. There is the same in Epson
UC inks but the ratios are much different. Polymer is the coating on the
paper that is anhydrous. When the ink dye and all the other good chemicals
hit the surface they swell the poly coating and embed themselves in the
surface. The transport chemicals (there are quite a few in there , including
water I would assume) evaporate leaving the dyes to bind in the surface
giving great permanence. Problem is matte papers are difficult to coat to
perform the same function.
>> The Glossy doesn¹t dry quickly at all on swellable papers.
>
> You mean to say that if I had an instrument to measure the decay of Gloss
> over time, was I measure the degree of Gloss in the HP 130 inks, I'd observe
> that the ink conserves its gloss for a fairly long time? Before it changes
> its optical appearance to something like matte?
Well sort of. It's the surface of the polymer coating that changes. When the
print first comes out it is actually wet, like a dark room print. When it
dries down the gloss fades back to around that of say Epson's old 190g/m2
photo paper.
>
>> On nanoporous as per Canon it dries quickly.
>
> Nanoporous paper by Canon? I'll bet Epson paper is not nanoporous in
> comparison?
Epson have both and matte papers too. It always sounds like marketing bs but
the HP Glossy and Satin papers are the best for their printers. I've
calibrated and profiled lots of other papers , third party and OEM'd papers
such as Epson. They can be good, available worldwide, and less expensive,
but the result is lesser quality.
>
>> I measured the inks over time and don¹t see that nice Epson 0.5 dE figure
>> anywhere near the 1 hour mark.
>
> OK. You say that when you measured the color of the solids in this HP 130
> inks over a period of an hour, you find more than a 0.5 dE shift in color?
> More like what, then? 1? 2?
Yes. Rather the overprinting colors to be exact. Just printed TC9.18 charts
and kept measuring periodically, first hours , then days, then weekly. Color
geeks do spend large amounts of time worrying about strange things you must
agree.
>
> Makes you wonder 'when' in HP's vocabulary is long term starting. 72 hours?
Around 72hrs on Glossy should be as stable as Epson UC after what 1hr?
>
>> It¹s stable short term but you have to know that the glycol is going to
>> evaporate.
>
> Just how stable, still, Neil?
Unless you want to measure with a polariser on a Spectrolino , you'd better
wait at least an hour. Then count on all colors that have over printing on
yellow to change chroma for a day. All other colors may change lightness
depending on the surface. For example the Satin Photo and Proofing is stable
quickly in lightness much faster. I would assume this is the expanded
surface area of the minute textured surface leading to faster evaporation of
the transport chemicals. These questions are indeed exactly what I need to
ask next time I'm with one of their chemists.
>
> And does that glycol evaporation occurs faster or slower as a consequence of
> relative humidity? Change of temperature? Should one keep the print inside
> for a few hours before lugging it around to a customer? What is that mean to
> us the fact that the glycol evaporates: it's it just another uncontrollable
> environmental factor or is this something we can something about?
On Glossy Photo and Proofing, yes 2 hrs would guarantee a dry to touch print
in average humidity. The Satin (my preferred paper) is dry to touch in 5
mins and dry to handle in 20 mins. The colors are stable enough for photo
presentation yet if proofing colors , named colors to be exact they would
not be ready within the first two hours.
>> When it does it changes the surface transparency so there is a
>> shift in values.
>
> So that glycol being used in the HP 130 inks (sorry to insist putting the
> dots on the I and the lines on the t), when it evaporates, as it will sooner
> or later, causes a change in the ink surface transparency? Thereby allowing
> more or less light to pass through the dye layer?
I think they dyes are very stable in themselves. Why? Because on a ceramic
coated paper the dyes are stable very quickly. So the reason that the colors
are less stable in lightness on the swellable papers must be because of
light diffusion as the surface of the paper changes. Again, I see the dyes
as being stable, yet the surface of swellable papers that create a shift in
appearance that of course a spectro will measure.
>
> But stable by when? And by how much?
See above, unfortunately stable on Glossy after 1 day in Paris type
humidity, less on Satin and undetermined on nanopourous.
>> yet I do see the L values moving due to the surface difference.
>
> Moving in which direction, Neil?
Mostly up by 1-2(max) on the darkest of colors, some strangely enough darker
>
> And what about the a and b values? Aren't those moving as well?
Almost dead stable on solids, yet as I said before overprinting yellows move
about.
>
> You mean to say that the 'secret' of the UC inks resides in their inks
> forming a physically stable layer on the paper?
Exact. You measure the little stones of colour, rather than the emulsion.
> You mean the dyes in the HP 130 inks are stable (rapidly)?
According to the studies by HP they are.
>> , yet the surface changes.
>
> You mean the surface formed by the dye on the paper is not stable itself
> because of that glycol evaporation?
Yes, when the water, glycol, demulsificants, antioxidants, etc etc leave our
prints to our stable dyes.
>
> Bottom line. The HP 130 ink formulation makes for unstable color right out
> of the printer. We don't know by when they actually become as stable as the
> Epson UC inks (0.5 dE). But the HP 130 inks don't exhibit Epson UC inks
> illuminant metamerism, they have a constant color appearance regardless of
> environement lighting, which makes them more "portable" than Epson's UC
> inks.
Yes The Epson is incredible for stability. The HP30/130 has cured the
problem of metamerism. Grey scale remain grey irregardless of the light. But
leaving the print cure with so many variables such as local relative
humidity and media surface will put the potential dE changes at risk for
consistent proofing on demand requirements. For 1 day to 82 years this maybe
good, but for on demand proofs (not talking photographs) won't be in the
0.5dE in the first day or even hours.
> From the HP 130 samples I seen at that show, I don't find the Epson 4000,
> 7600 and 9600 to be that much sharper. But that's my assesment.
The HP actually prints higher detail at lower resolution numbers than Epson
drivers. In the end a photographer should be more concerned about printing
the actual detail in the image than the actual dot size. As proofer though
the actual dot size and shape and placement is critical for 1 bit tiff
printing.
--
Neil Snape photographer Paris France email@hidden
http://www.neilsnape.com
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