Digital BW, The Print

Ernst Dinkla <e.dinkla@...> wrote:
>
...
> In that case tests with Epson R800, R1800, Z3100, Z3200 printers and 
> third party inks for mentioned printers should be checked.
> 
> I went along the Epson Premium Luster tests with said printers 
> and I see 
> a slight negative change on the paper white shifts if compared to 
> printers without a gloss enhancer (Epson 4800, Epson 2200), ...


The variance among the tests is surprising.  Looking just at the Epson Premium Luster paper white samples at 100 Mlux-hours, the I* Color for the printers with no gloss optimizer in them were 
92.9 for a 2200 (AaI_20080309_SN002Lf.pdf), 
88.5 for a 4800 (AaI_20071218_SN009Lf.pdf), and 
79.7 for a 3800 (AaI_20090510_SN001Lf.pdf).  


The 1800 with OEM inks had an I* Color of 82.2 (AaI_20071008_SN013Lf.pdf), and the 1800 with MIS glop in it had an I* Color of 83.8. (AaI_20071008_SN007Lf.pdf)

Given the variance we see in the bare paper whites, I'm not sure we can conclude much about the gloss optimizers.

In retrospect, I think a critical piece of information at the outset would be to know whether the OBAs are in the paper base or coating. If it is in the paper, protected by polyethylene, it's hard to see what impact gloss optimizer would have on them.

Overall, however, the numbers you extracted from the data do tend to show more paper white change when gloss optimizer is used.

 
> The contrast with samples sprayed with a protective varnish 
> is even more pronounced so we should forget that a gloss 
> enhancer has a similar quality, it is rather the opposite.

With the sprays, the issue I'd be curious about is the UV blocking effect v. some effect of slowing down oxidation.


Paul
www.PaulRoark.com