Digital BW, The Print

Ernst,

>Paul Roark wrote:
>>...The green shift is a problem
>> that has shown up on my 7500 when it is not used for 
>>more than a month...  
>>It's non-use of the printer that seems to cause this.  
>>I just loaded a new beta UT1 toner in my 7500 and hope that 
>>it'll take care of the problem...
>>Using the printer at least every few days should avoid the problem.

>... it looks like it happens much faster and less predictable.

>Wednesday I got that green shift of the light toner for the first 
>time in my 9000 but it has been idle for longer periods before 
>and this time it was less than 4 days.

Is it possible that the inks separated in the carts when idle for the longer
period and you had been using ink in the lines that was not separated for a
period?

>Is this pigment settling?  I'm not so sure, looks more like they 
>used two pigment hues and the magenta degrades in the mix.  One 
>would expect a single hue pigment for a toner that has to last.

When the ink is agitated, it returns to its former hue, from what I can
tell.  So, this seems to indicate to me that it is probably a settling
problem.

In desktop units, the head agitates the mix regularly.  So, the problem does
not seen to exist for most users.  The sponges may also be a factor.  My
7500 seems to agitate the pigments enough due to the stand rocking slightly.
(You'd once mentioned this, I thought at least in part as a joke.  However,
I think you were right on, as usual.)

The beta toner I'm testing in my 7500 uses the R800 clone "blue" pigment.
This is part of the Ultra Tone family of inks.  While it is on the magenta
side of my target, it allows me to move considerably closer to a
single-color toner.  I have to use a bit of cyan, but cyan has always been
rock solid.  The pigments seem to be well matched in their physical
characteristics.  So, I'm waiting for the end of the month to see how the
fade test looks.  Also, of course, the ink is sitting in the 7500, and I'll
let it sit idle for long while.

Note that pigments are often mixed.  I don't think the mixing is necessarily
a negative, as long as the characteristics of the pigments are appropriately
matched.

Paul
www.PaulRoark.com