Puzzled about Wilhelm Imaging Research results

Hi,

I've not visited the website for a while now, seems to have finally revamped it and now have many new updates.

I was reading the permanance ratings for the silver halides compared to the other dye and pigment ink prints. I'm sooooooooooooooooo surprised to see the silver halides eg. FujiFilm Crystal Archive having lower permanance ratings than the pigment-based inks and some of the dye-based inks eg. HP DesignJet 130.

http://www.wilhelm-research.com/4x6/4x6_permanence_preview.html

I'm always under the assumption that silver halide prints have the longest longevity, even compared to pigment-based prints. How reliable are those resuls anyway? I thought silver halides would last over 100 years.

I have a Canon S9000 and only use it for A4/A3 prints, while I send large batch jobs of 5" X 7" for FujiFilm printing. However, lately I find that I'm sending more of A4 size photos for online printing mainly becoz' I want them to last longer.

If those results are really accurate, I'm really disappointed. Perhaps I should invest in the R1800.

However, although Wilhelm has certainly been considered the "Gold" standard in evaluating of permanence of film etc., he has certainly not been infallible. He literally wrote the book on the subject.

He completely missed stability problems with older Epson printers. Accelerated testing didn't reveal problems that occurred in real life. Hopefully the newer testing methods are now valid.

Read and form your own conclusions, but inkjet printers a few years ago were considered a joke in terms of permanence, whereas today many appear to print stable beautiful prints There are exceptions for sure, and lot of variables to consider.

john

I have little faith in Wilhelms' results for a variety of reasons. First, his methodology is suspect. Wilhelm uses fluroescent lighting - not typical lighting in most home environments (mix of natural light and incandescent) and the amount of exposure is exceedingly low (450 lux). There are potential conflict of interest issues as well.

For a more realistic evaluation check out http://www.livick.com

I thought the same as you are thinking once ( silver halide is it, the best you can do). That was until I walked into a customers house whoes wedding I shot 7 years prior, to find Fuji Crystal Archive prints ( at the time advertised with 60 year life and the standard of the industry for longevity) to be noticably faded !!! They were framed and on a mantle in a rather bright daylight lit room, no direct sun just bright.

Now Crystal Archive Pro is about the longest lasting silver halide out there, I think both Livick and Wilhlem have tested silver halide which lasts considerably shorter ( especially some pro Agfa papers).

No , I think the new standard for longevity is pigmnented ink on certain papers and regardless of the test methods, this seems to still show as a true fact. Test results may not be dead nuts accurate, but if the same standards are used accross the board for various papers you get a feel for what lasts best and not so well, at least in a general way.

That all said, I wouldn't sell anyone a print based on decent longevity that was printed from a dye based printer, especially Canon. You have issues from fade, to glass sticking to no water resistance to think of. You don't know what your customers will do with the prints once they leave your studio. I feel reasonably confident in R800 and 2200 prints lasting at least as well as silver halide and with a touch more gamut at the same time. I'm sure the R1800 is a winner as well.

Silver halide still wins in terms of scuff resistance.

David

SweeJ said:

Hi,

I've not visited the website for a while now, seems to have finally
revamped it and now have many new updates.

I was reading the permanance ratings for the silver halides
compared to the other dye and pigment ink prints. I'm
sooooooooooooooooo surprised to see the silver halides eg.
FujiFilm Crystal Archive having lower permanance ratings than the
pigment-based inks and some of the dye-based inks eg. HP DesignJet
130.

http://www.wilhelm-research.com/4x6/4x6_permanence_preview.html

I'm always under the assumption that silver halide prints have the
longest longevity, even compared to pigment-based prints. How
reliable are those resuls anyway? I thought silver halides would
last over 100 years.

I have a Canon S9000 and only use it for A4/A3 prints, while I send
large batch jobs of 5" X 7" for FujiFilm printing. However, lately
I find that I'm sending more of A4 size photos for online printing
mainly becoz' I want them to last longer.

If those results are really accurate, I'm really disappointed.
Perhaps I should invest in the R1800.

Click to expand...

Adam2 said:

For a more realistic evaluation check out http://www.livick.com

Click to expand...

I don't know. Livick's tests are without glass and Wilhelm-Research's are with glass. So the numbers are pretty close.

--

'Do not go where the path may lead, go where there is no path and leave a trail.'

There are other distinctions as well. Livick uses direct sunlight (if I'm not mistaken) and extrapolates his results from total exposure. Wilhelm uses approximately 450 lux/12 h. day v. 275 lux x 10 hr/d. I think it is worthwhile reviewing the methodology and stated claims.

THe bottom line is this:

"Without any protective coatings you could only have about 25 years of print life with Ultrachrome pigment inks and their like, printed on ink jet receptive watercolour papers. BUT that's only when they are being displayed on an normal home apartment or office wall with just a very moderate 275 Lux value daily average lighting. And at that 25 year mark there will be a progressively accumulated 30% fade out in some of the primary colours, mainly the Yellow or Cyan."

You can't do a relaible, controlled test with sunlight. There are way too many variables (intensity and direction of sunlight, other amospheric variables, etc.).

Both Livick's and Wilhelm's tests are suspect, and are only acurate in the conditions they were performed. Most prints are designed to withstand a normal amount of light over a number of years, not overwhelmed with light over a small amount of time (of course, ink companies may be designing their ink to witstand tests like Wilhelm's or Livick's better, but that could come at the cost of real life longetivity).

Adam2 said:

There are other distinctions as well. Livick uses direct sunlight
(if I'm not mistaken) and extrapolates his results from total
exposure. Wilhelm uses approximately 450 lux/12 h. day v. 275 lux
x 10 hr/d. I think it is worthwhile reviewing the methodology and
stated claims.

THe bottom line is this:

"Without any protective coatings you could only have about 25 years
of print life with Ultrachrome pigment inks and their like, printed
on ink jet receptive watercolour papers. BUT that's only when they
are being displayed on an normal home apartment or office wall with
just a very moderate 275 Lux value daily average lighting. And at
that 25 year mark there will be a progressively accumulated 30%
fade out in some of the primary colours, mainly the Yellow or Cyan."

Click to expand...

--
dgrogers

http://www.pbase.com/drog

Thanks for your replies.

I have to agree both differ in their methodology. What Livick does stress is prints in the home setting are generally exposed to natural daylight (UV light?) while Wilhelm has maintained flourescent light exposure, which Livick states is probably applies if in an office setting.

Both use different lux intensities at different periods of exposure each day. Livick mainly don't cover the prints behind a glass, while Wilhelm tests for both, and also other enviromental settings eg stored dark/in a album, ozone, etc.

I'm trying to figure out if both methods can somehow be compared and show that the ratings are similar/different. However, both websites don't test all printers. Livick doesn't have the newer Epson R800/R1800 and HP130/HP8750 whie Wilhelm don't do Canon.

I'm trying to figure out ratings for FujiFilm Crystal Archive, cuz' I'm trying to find out if silver halide really lives up to its reknown longevity rating.

Livick: 65.2 years, 275 lux UV light 10hrs/day, unprotected
Wilhelm: 40 years, 450 lux flourescent light 12hrs/day, glass protected

I realise there are many variables & confounding factors eg humidity, air movement, pollutants, etc, but if I took these at face value, does this mean at 2/3 lux intensity (275 lux / 450 lux) at similar length of exposures (10 ~ 12 hours), a print will have 2/3rd longevity (40 / 65.2 years), REGARDLESS of the type of lighting and level of protection?

Or does this mean, flourescent lighting is much much more intense, and requires a glass protection to achieve the same ratings as a UV/natural light exposure? Doesn't this conflict with Livick's observation:

" FLUORESCENT LIGHTING IS VERY SLOW, IN FACT FEEBLE AND ARTHRITIC WHEN IT COMES TO FADING PIGMENTED INKS. CONSEQUENTLY ANY FADE TESTING ORGANIZATION WORKING WITH FLUORESCENT LIGHTING AS THEIR MAIN SOURCE OF ILLUMINATION, IS NOT ACTUALLY ACCOUNTING FOR A MAJORITY OF PRINT DISPLAY CONDITIONS. EXTRAPOLATIONS WORKED OUT UNDER FLUORESCENT LIGHTING WILL YIELD RATINGS FOR EPSON'S LATEST ULTRACHROME INKS THAT ARE APPROXIMATELY 2/3 HIGHER THAN NORMAL DAYLIGHT RATINGS. IF YOU MULTIPLY THOSE FLUORESCENT FADE RATINGS BY .33% IT WILL REFLECT A MORE ACCURATE RATING FOR DAYLIGHT DISPLAY CONDITIONS WHEN USING THE ULTRACHROME TYPE OF INKS. "

I apologize, I know my analysis is very crude but it's something I though about when comparing both websites.

dgrogers:

I wholely agree, perhaps exposure in a short period of time will not show real life results of fading. I think it will be impossible to compare say a print that was taken 10 years and how it faded, and conduct light exposure of the same unaffect print under Livick/Wilhelm methods of lux exposure. It will be interesting if someone started a cohort study and see how the prints look say 5 years time. It is my opinion that all (pigment, dye, silver halide) will show fading before 10 years.

dgrogers said:

Both Livick's and Wilhelm's tests are suspect, and are only acurate
in the conditions they were performed. Most prints are designed to
withstand a normal amount of light over a number of years, not
overwhelmed with light over a small amount of time (of course, ink
companies may be designing their ink to witstand tests like
Wilhelm's or Livick's better, but that could come at the cost of
real life longetivity).

Adam2 said:

There are other distinctions as well. Livick uses direct sunlight
(if I'm not mistaken) and extrapolates his results from total
exposure. Wilhelm uses approximately 450 lux/12 h. day v. 275 lux
x 10 hr/d. I think it is worthwhile reviewing the methodology and
stated claims.

THe bottom line is this:

"Without any protective coatings you could only have about 25 years
of print life with Ultrachrome pigment inks and their like, printed
on ink jet receptive watercolour papers. BUT that's only when they
are being displayed on an normal home apartment or office wall with
just a very moderate 275 Lux value daily average lighting. And at
that 25 year mark there will be a progressively accumulated 30%
fade out in some of the primary colours, mainly the Yellow or Cyan."

Click to expand...

--
dgrogers

http://www.pbase.com/drog

Click to expand...

Yeah, may main gripe now is that (if those results are valid) silver halide have a relatively poor longevity compared to pigment-based prints.

I've not been around this forum much, but have you come across anyone who has complained their pigment-based prints have already started showing signs of fading? I know for the dye prints, fading is a common issue, however the new Vivera HP inks have been given very high ratings. Again, they are only ratings; I think it's still too new to hear from owners of any fading issues.

And sorry, what do you mean by scuff resistance?

David Grabowski said:

Now Crystal Archive Pro is about the longest lasting silver halide
out there, I think both Livick and Wilhlem have tested silver
halide which lasts considerably shorter ( especially some pro Agfa
papers).

No , I think the new standard for longevity is pigmnented ink on
certain papers and regardless of the test methods, this seems to
still show as a true fact. Test results may not be dead nuts
accurate, but if the same standards are used accross the board for
various papers you get a feel for what lasts best and not so well,
at least in a general way.

That all said, I wouldn't sell anyone a print based on decent
longevity that was printed from a dye based printer, especially
Canon. You have issues from fade, to glass sticking to no water
resistance to think of. You don't know what your customers will do
with the prints once they leave your studio. I feel reasonably
confident in R800 and 2200 prints lasting at least as well as
silver halide and with a touch more gamut at the same time. I'm
sure the R1800 is a winner as well.

Silver halide still wins in terms of scuff resistance.

David

SweeJ said:

Hi,

I've not visited the website for a while now, seems to have finally
revamped it and now have many new updates.

I was reading the permanance ratings for the silver halides
compared to the other dye and pigment ink prints. I'm
sooooooooooooooooo surprised to see the silver halides eg.
FujiFilm Crystal Archive having lower permanance ratings than the
pigment-based inks and some of the dye-based inks eg. HP DesignJet
130.

http://www.wilhelm-research.com/4x6/4x6_permanence_preview.html

I'm always under the assumption that silver halide prints have the
longest longevity, even compared to pigment-based prints. How
reliable are those resuls anyway? I thought silver halides would
last over 100 years.

I have a Canon S9000 and only use it for A4/A3 prints, while I send
large batch jobs of 5" X 7" for FujiFilm printing. However, lately
I find that I'm sending more of A4 size photos for online printing
mainly becoz' I want them to last longer.

If those results are really accurate, I'm really disappointed.
Perhaps I should invest in the R1800.

Click to expand...

Click to expand...

I think that you've recognized the inherent limitations of these testing methodologies. Like many processes in nature, we don't know whether the damage is subject to a threshold effect, is cumulative, or indeed linear.

Your points about silver halide prints are well taken. When I look at my own experience with commercial printing it has been highly variable. I've archival albums filled with prints from the late 70's which have faded miserably while prints from a few years earlier are pristine (same storage conditions, etc.). The same holds true for framed prints.

While there is a lot of argument over whose methodology is more exacting (Livick v. Wilhelm), I think that it behooves one to subscribe to the "worst case" scenario and use that data. In the interim, I still plan on using pigment based inks on acid free fine art paper and framing or storing them in the best possible conditions. Unfortunately, daguerreotypes have gone out of fashion - besides I get enough mercury from my fish these days ;-))

SweeJ said:

Yeah, may main gripe now is that (if those results are valid)
silver halide have a relatively poor longevity compared to
pigment-based prints.

Click to expand...

I wouldn't get too hung up on this. Fuji Crystal Archive Pro is a respected paper. Ultrachrome inkjet on pro grade papers is also a respected means of printing now. I have both out there in albums and on walls around the country with 0 complaints concerning fade ( the one I spotted myself was a surprise though) . I do know that you can grab a little more range out of inkjet prints than from chemical of the same image and I can print in house with the Epson Ultrachrome and give a decent product to my clients.

SweeJ said:

I've not been around this forum much, but have you come across
anyone who has complained their pigment-based prints have already
started showing signs of fading?

Click to expand...

No, I have not read of complaints concerning fade and I've had no incidents of fade what so ever from either the 2200 or R800 printers. I did have problems with the 1200 and 1280 printers and their dye inks to the point I wouldn't sell prints from them. in one room here dye ink prints if left out unprotected would print after print fade in less than 6 months, I've had pigment ink prints in that room unprodected for over two years with no signs of fade at all.

SweeJ said:

I know for the dye prints, fading
is a common issue, however the new Vivera HP inks have been given
very high ratings. Again, they are only ratings; I think it's still
too new to hear from owners of any fading issues.

Click to expand...

True, I know nothing of these as well, not yet.

SweeJ said:

And sorry, what do you mean by scuff resistance?

Click to expand...

Drop a print on the floor face down, will it scratch or not scratch ? Silver halide might be a bit tougher in this regard depending on the paper used. Same for album use where prints may rub in the pages, especially open faced or so called flush mount. How about wallets ? Pigment ink sits on the surface subject to wear, the R1800 and r800 do put on a clear coat designed for gloss and I have found they seem more resiliant ( others can argue their point on this, I'm just explaining my personal experience) than 2200 prints with no gloss coat ( though I spray coat those, so they actually are pretty tough).

David

SweeJ said:

David Grabowski said:

Now Crystal Archive Pro is about the longest lasting silver halide
out there, I think both Livick and Wilhlem have tested silver
halide which lasts considerably shorter ( especially some pro Agfa
papers).

No , I think the new standard for longevity is pigmnented ink on
certain papers and regardless of the test methods, this seems to
still show as a true fact. Test results may not be dead nuts
accurate, but if the same standards are used accross the board for
various papers you get a feel for what lasts best and not so well,
at least in a general way.

That all said, I wouldn't sell anyone a print based on decent
longevity that was printed from a dye based printer, especially
Canon. You have issues from fade, to glass sticking to no water
resistance to think of. You don't know what your customers will do
with the prints once they leave your studio. I feel reasonably
confident in R800 and 2200 prints lasting at least as well as
silver halide and with a touch more gamut at the same time. I'm
sure the R1800 is a winner as well.

Silver halide still wins in terms of scuff resistance.

David

SweeJ said:

Hi,

I've not visited the website for a while now, seems to have finally
revamped it and now have many new updates.

I was reading the permanance ratings for the silver halides
compared to the other dye and pigment ink prints. I'm
sooooooooooooooooo surprised to see the silver halides eg.
FujiFilm Crystal Archive having lower permanance ratings than the
pigment-based inks and some of the dye-based inks eg. HP DesignJet
130.

http://www.wilhelm-research.com/4x6/4x6_permanence_preview.html

I'm always under the assumption that silver halide prints have the
longest longevity, even compared to pigment-based prints. How
reliable are those resuls anyway? I thought silver halides would
last over 100 years.

I have a Canon S9000 and only use it for A4/A3 prints, while I send
large batch jobs of 5" X 7" for FujiFilm printing. However, lately
I find that I'm sending more of A4 size photos for online printing
mainly becoz' I want them to last longer.

If those results are really accurate, I'm really disappointed.
Perhaps I should invest in the R1800.

Click to expand...

Click to expand...

Click to expand...

I think that Livik is a bit over the top in his criticism of the Wilhelm numbers. I did quite a bit of discussion with him when he started this quite some time ago and his expertise on fading processes seemed somewhat limited. For example, florescent lights have significant amounts of UV light which is a major factor in fading despite what he says. This is why good prints in museums and such are often displayed under low intensity incandescent lights. These lights have very little UV due to their low effective radiating temperatures. His testing and not using glass in sunlight is suspect because glass filters some wavelengths of sunlight and thus provides some protection under most conditions. In any event, you have to take all these numbers with a grain of salt in an absolute sense, both the Livik and Wilhelm numbers. There are just too many variables in where and how people display prints. There is value, IMHO, in the relative comparisons between paper/ink combinations in indicating combinations that likely will have better longevity under certain conditions. Regarding test conditions, Wilhelm seems to test under very controlled condtions which are the same for all his tests unless stated otherwise. I would give the Wilhelm numbers the node because the Livik tests don't seem to be quite as controlled and, regarding using direct sunlight and no glass, may not be very representative of most folks display conditions. I did a lot of testing of my own some years ago (see many messages from my early years) and did not find any significant problems with the relative rankings of paper/ink combinations from the Wilhelm numbers. Wilhelm did not anticipate the gas fading problem with some dye based inks but I don't think anyone anticipated that.
--
Leon
http://homepage.mac.com/leonwittwer/landscapes.htm

although the unexposed, unprocessed paper contains silver halide. However the final (fully processed) image consists of plain ol' organic dyes, which are subject to fading like all other dyes--some faster, some more slowly. Generically, there is no reason to expect that a silver-halide based color paper will have, in your words, "longest longevity". So, yes, as you suspect, a good (pigment-ink) inkjet printer just might offer the very best print longevity you can obtain at this time.

Phil

SweeJ said:

Hi,

I've not visited the website for a while now, seems to have finally
revamped it and now have many new updates.

I was reading the permanance ratings for the silver halides
compared to the other dye and pigment ink prints. I'm
sooooooooooooooooo surprised to see the silver halides eg.
FujiFilm Crystal Archive having lower permanance ratings than the
pigment-based inks and some of the dye-based inks eg. HP DesignJet
130.

http://www.wilhelm-research.com/4x6/4x6_permanence_preview.html

I'm always under the assumption that silver halide prints have the
longest longevity, even compared to pigment-based prints. How
reliable are those resuls anyway? I thought silver halides would
last over 100 years.

I have a Canon S9000 and only use it for A4/A3 prints, while I send
large batch jobs of 5" X 7" for FujiFilm printing. However, lately
I find that I'm sending more of A4 size photos for online printing
mainly becoz' I want them to last longer.

If those results are really accurate, I'm really disappointed.
Perhaps I should invest in the R1800.

Click to expand...

Phil Rose said:

although the unexposed, unprocessed paper contains silver halide.
However the final (fully processed) image consists of plain ol'
organic dyes, which are subject to fading like all other dyes--some
faster, some more slowly. Generically, there is no reason to expect
that a silver-halide based color paper will have, in your words,
"longest longevity".

Click to expand...

Here is a patent that touches on this mechanism:
http://www.freepatentsonline.com/5731136.html

Hmmm.... it's a pity silver halide don't really last that long.

Though I'd really like to have A4/A3 prints from a pigment-ink printer (I love the ability to see your own prints created from home!), I still prefer to have 7" X 5" prints processed from labs. This is especially convenient for me when I take over 200 photos when I'm on a holiday, and it will be way easier to have them sent to a lab than print them at home.

Phil Rose said:

although the unexposed, unprocessed paper contains silver halide.
However the final (fully processed) image consists of plain ol'
organic dyes, which are subject to fading like all other dyes--some
faster, some more slowly. Generically, there is no reason to expect
that a silver-halide based color paper will have, in your words,
"longest longevity". So, yes, as you suspect, a good (pigment-ink)
inkjet printer just might offer the very best print longevity you
can obtain at this time.

Phil

Click to expand...

David Grabowski said:

No, I have not read of complaints concerning fade and I've had no
incidents of fade what so ever from either the 2200 or R800
printers. I did have problems with the 1200 and 1280 printers and
their dye inks to the point I wouldn't sell prints from them. in
one room here dye ink prints if left out unprotected would print
after print fade in less than 6 months, I've had pigment ink prints
in that room unprodected for over two years with no signs of fade
at all.

Click to expand...

Yes, I do realise that for larger format prints, pigement inks are the way to go for longevity. Also, would I dare say that the quality from these new printers exceed those produced from a photo lab?

So, I guess you're rite, I shouldn't get too disappointed about silver halides since I will now be considering to have them mostly in 7 X 5 sizes. They will probably last much longer unexposed as I only keep them all in a photo albums or wallets.

David Grabowski said:

David Grabowski said:

And sorry, what do you mean by scuff resistance?

Click to expand...

Drop a print on the floor face down, will it scratch or not scratch
? Silver halide might be a bit tougher in this regard depending on
the paper used. Same for album use where prints may rub in the
pages, especially open faced or so called flush mount. How about
wallets ? Pigment ink sits on the surface subject to wear, the
R1800 and r800 do put on a clear coat designed for gloss and I have
found they seem more resiliant ( others can argue their point on
this, I'm just explaining my personal experience) than 2200 prints
with no gloss coat ( though I spray coat those, so they actually
are pretty tough).

David

Click to expand...

Ah yes, I understand what you mean by scuff resistance now, thanks.

Hi Leon,

You mentioned gas fading. I'm slowly discovering other factors apart from UV light exposure, but does gas fading have a greater/lesser effect than exposure to light?

I know you can cover a photo with glass to reduce UV-light fading, how about protection from gas fading?

Leon Wittwer said:

I think that Livik is a bit over the top in his criticism of the
Wilhelm numbers. I did quite a bit of discussion with him when he
started this quite some time ago and his expertise on fading
processes seemed somewhat limited. For example, florescent lights
have significant amounts of UV light which is a major factor in
fading despite what he says. This is why good prints in museums
and such are often displayed under low intensity incandescent
lights. These lights have very little UV due to their low
effective radiating temperatures. His testing and not using glass
in sunlight is suspect because glass filters some wavelengths of
sunlight and thus provides some protection under most conditions.
In any event, you have to take all these numbers with a grain of
salt in an absolute sense, both the Livik and Wilhelm numbers.
There are just too many variables in where and how people display
prints. There is value, IMHO, in the relative comparisons between
paper/ink combinations in indicating combinations that likely will
have better longevity under certain conditions. Regarding test
conditions, Wilhelm seems to test under very controlled condtions
which are the same for all his tests unless stated otherwise. I
would give the Wilhelm numbers the node because the Livik tests
don't seem to be quite as controlled and, regarding using direct
sunlight and no glass, may not be very representative of most folks
display conditions. I did a lot of testing of my own some years
ago (see many messages from my early years) and did not find any
significant problems with the relative rankings of paper/ink
combinations from the Wilhelm numbers. Wilhelm did not anticipate
the gas fading problem with some dye based inks but I don't think
anyone anticipated that.
--
Leon
http://homepage.mac.com/leonwittwer/landscapes.htm

Click to expand...

Gas fading became prominent when Epson came out with the dye based ink set used in the 1270 although the problem may have predated that printer but just not picked up by enough people. The problem is that various contaminants in the air attacked the dyes causing fading. Some fading could occur in hours to days. A number of things in the air were implicated including ozone and NO. The list is likely larger. Epson responded with papers that would protect the inks better from the air. An obvious solution is to mount prints under glass and sealing the inks away from the air circulation. Another is using pigment based inks. It is likely that the Epson 2000P was a response to the gas fading problem and the larger vulnerability of dye based inks to light fading as well. The 2000P was "ok" but was somewhat limited in the color gamut and had significant metamerism under some lighting. The ink set for the 2200/2100 was the upgrade that largerly solved these problems. Mounting under glass is still indicated if only to protect from dirt, etc. Of course, you have to use the appropriate ink/paper combination to get the best longevity.
--
Leon
http://homepage.mac.com/leonwittwer/landscapes.htm

Hello,

Just for a bit of clarification.. Stephen Livick and I did fade testing on
many combinations of inks and papers...over 7,000 readings taken.

We tested the prints in sunlight. We tested the prints uncovered, with plain glass, and with UV glass. Plain glass gave about a 5% increase in
longevity; UV glass gave about 10%.

We tested for gas fade. We also tested for age fade or paper and ink changes over time by subjecting prints to heat in a lab control oven to see how the prints might hold up in 100, 200, and 300 years.

Bill