Digital BW, The Print

Sam,

But no-one knows how RIT and Wilhelm's tests will stand-up in the long run
either! Many people suggest that attempting to extrapolate a 'display life'
from xx minutes under a strong lamp is just plain wrong. Well, I understand
it is inevitable that someone should do that - but I fear it leads to too
many assumptions on the part of the purchaser or even the person doing the
printing! Some longevity 'reports' do not even state clearly what paper they
were using - let alone all the other factors that are expected - or even
'batch number of ink tested' (if colours can drift slightly between batches,
and I would assume they can - what would the impact be on the longevity?) My
understanding is that ink tests now tend to be done on a single colour basis
(e.g. test the life of the Yellow ink separate from th Cyan ink) which is
great until you hear that mixing might occur of inks when you print a
photographic image, which could result in less stable compounds. e.g.
perhaps one ink prints a longer-lasting Red than another ink-set.

As little as 6 months ago - I would estimate that the general perception on
the groups I browse was that if an ink lasted well on one paper - it would
do so on another! Even this has now been taken away from us with the strong
differentiation between coatings for pigments and surfaces most appropriate
for dyes - and how having the wrong surface for the ink can negatively
effect longevity.

I think even some people who should know better would be surprised if their
'100+ year ink' didn't last on tissue paper ;)

BUT we also have to remember, whatever our own personal goals, that
Watercolours are going to fade... that dyed fabrics are going to fade (a
local framing shop recently started selling pictures made up from  many
different fabrics - I wonder how many people asked how long the colour on
them would last!)

So one point to make is  - you have to find a solution you are happy with
for now, that you can justify without being overly bullish about it's
probably lifetime... (i.e. self satisfaction)... and then you need to find a
way to 'sell' that decision to your customers who will probably just want to
be told something like a number of years expected! In that sense, RIT and
Wilhelm results are very useful, even though they tell only a small fraction
of the story, I am sure!

Best regards,
Nij



> -----Original Message-----
> From: Sam A. McCandless [mailto:samcc@...]
> Sent: 19 December 2001 15:13
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: Re: [Digital BW] print sales - longevity claims?
>
>
> I'm uneasy with Julian's answer, partly because I don't think we
> should say anything on our own authority because I don't think we
> know. I think we should point people to credible independent testers
> such as RIT and Wilhelm. If we do, won't they find color prints with
> longer lifespans than BW? My guess is that's only because some ink
> manufacturers have been investing in the testing longer than others
> or have been testing color but not quadtones. I think it would take a
> fairly long and elaborate answer to include such interpretive notes,
> and an even longer and more elaborate one to say anything very
> encouraging about ink-and-paper combinations not tested by any third
> party. That would be good to do, I think, and might result in
> something useful as a handout or enclosure, but I'm afraid it's a
> major project.
>
> Sam
>