Digital BW, The Print

> I had a poster up in a cafe ... and in a year it had 
> gone quite green - that was with Ultrachromes on 
> Epson Matte Heavyweight. I don't know how much 
> protection plain glass gives - not much I would think.

That's a bit disturbing.  I doubt the paper is the main culprit.  I'd guess
the café has lots of windows that let in sunlight.  The UV simply wiped out
the magenta pigments -- the weaklings in our B&W setups.  (I'm not sure if
this poster was B&W or color.  My comments are aimed at B&W.)

Plain glass filters out the worst (shortest wavelengths) of the UV, but
sunlight still has lots of UV that will get through.  The café probably has
windows that take care of the short UV.  So, your plain glass over the image
didn't add much.

UV glass would definitely help.  Even plain acrylic would help a bit -- but
not that much.

A UV spray would help also, and it might be cheaper than the UV glass.  The
2 together might be the best bet. 

Don't use the OEM Epson B&W solutions.  They have more of the weak magenta
in them.

Print with a tone that is as warm as looks good in the circumstances.  The
warmer the tone, the less magenta there is to fade.  It'll also hide the
green shift a bit more.  MIS carbon does not fade to green.  The more of the
image that is carbon, the better. 

And, of course, switch to a better paper.

For the current museum project I'm on, I'm using MIS 3D inks (use R800 blue
and no magenta) and Premier Art Fine Art Hot Press 325.  (This coating --
same as Ultra Smooth -- does the best in my fade tests and also Wilhelm's.)
I'm printing them with a medium warm tone and spraying them with PremierArt
Print Shield, which has a UV blocker.  

One does need to take the advertised "years of display" with a grain of
salt.  These are based on rather ideal circumstances.  Fading is still a
risk that needs to be managed.

Paul
www.PaulRoark.com