Metamerism or bronzing?


#1

Hi Walker
I am trying to get printing on my 9800 loaded with PiezoPro ink.
Printing a test image on Felix Schoeller TrueRagSilk paper using the Canson Platine supplied curves.
There is a visible ‘purple’ or ‘metallic’ sheen when the print is viewed at certain angles. Almost looks like oil on water, a kind of purple shimmer? I am attaching a pic of the test print, its a bit difficult to see, I enhanced the purple in photoshop to make it more visible on the screen, definitely clearly visible to the naked eye on the print.
Any idea what is the casue?
Is this what is referred to as metamerism? Its not what I understand to be bronzing (gloss differential)?

thanks
Neil


#2

FWIW, what I see in your first picture is bronzing (not metamerism and not gloss differential). Gloss differential (something different) is a noticeable difference in the amount of sheen (or uneven sheen) which typically is most noticeable in the very high values of an inkjet print near paper white. There is no color shift related to gloss differential.

Bronzing generally results from interaction between ink formulation (refractive index), the paper coating, and angle/wavelength of light being reflected. Typically some colors in the print seem to show it more prominently, e.g. blue/cyan.

Not sure why you are seeing it so prominently. I’m not familiar with the paper you are using but I use Canson Platine and Piezography Pro (using a 7900) and do not see any bronzing at all.

If I had to guess for a place to start troubleshooting, I would recommend making sure your inks (including GCO) are completely free of any PiezoFlush or color ink remnants resulting from flushing before loading your PiezoPro inks. On the larger format printers, there can be a LOT of staining from residual ink/PiezoFlush in the ink tubes and dampers until it is all cleared.


#3

Because of the incredible high ink-load of Piezography relative to any other monochromatic ink systems, some bronzing on some papers is inevitable. Generally bronzing is most noticeable with window-light at a 45 degree angle. If this particular paper/ink combo is going to be shown in window light and not behind glass or anything else, than this could be a slight issue with this paper and other papers like Hahnemuhle Photo Gloss Baryta may be needed. If not, I suggest putting the printer under gallery flood and view it at the same angle to verify under display conditions.

As above poster said, other interactions between residual pigment/ink/paper-type can effect it as well.

 

best,

Walker


#4

Thanks for the responses and for confirming that it is some form of bronzing. I suspect that the cause is residual flush or ink in the lines or dampers, I have had other problems caused by ‘contamination’ as well. If I was to convert an older large format machine again, I would definitely include a damper change in the process. I did do an initial fill with flush and left it for 48 hrs before loading the inks, I but I have still had issues with residual ink. I suspect changing the dampers while it was filled with flush would have been the way to go. Next time :slight_smile: !