Digital BW, The Print

"Nij" <nigel@...> wrote:

>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!

and I agree both with his conclusion and with his thinking that we 
need to be concerned about expectations based on test reports. Still, 
I wish we had that problem with all our prints.

Sam