By
Calvin Siew
01/02/2005
URL:
http://asia.cnet.com/reviews/printers/0,39051182,39164439,00.htm
In the history of communication
materials, paper has definitely proven the most popular in terms of writing
or drawing. Since AD 105, papermakers have developed a number of specialty
media such as coated and dyed paper. Until this day, much hasn't changed and
there are even more types of media. Hence, the sheets of cellulose pulp between
manufacturers aren't always the same.

Photo courtesy of
HP |
|
As discussed in the first
part of our series on photo printing, having a great printer with wonderful
inks is not the full solution. We judge a product based on its outputs, and
prints consist not just of inks but paper as well. The market today is filled
with variants of paper, ranging from archival to watercolor, to photo. Even
more confusing are terms such as porous and swellable, used to describe the
coatings. Just what do those geek-sounding jargon mean and what can they do
for you?
Is fading inevitable?
In the photo printing space, the term "fade resistance" applies
to the ability of the print outputs to combat fading due to exposure to light
or other fade-inducing agents (Ozone) in the air. Through their own and independent
lab tests, manufacturers often rate the durability of their photos in years.
To do so, they determine the types of chemicals and environments that cause
the colorants to fade and accelerate the process. The fade-resistant lifetimes
of the media are accurate only for light fading as there are currently no
standard methods for estimating and accelerating air-induced fade.
Light fading is caused by both visible light and ultraviolet radiation. These
agents break up the colorants over time and cause them to lose those bright,
saturated colors, leaving photos looking dull and plain.
Air-induced fading occurs when fade agents such as Ozone get absorbed into
the pores of the prints. These agents attack the dyes and cause them to break
down, losing the colors. Ever wondered why some of your prints fade even though
you've kept them in an album and away from light?
The two main
types of photo paper
Premium-grade photo papers
from the various manufacturers are generally made from sheets that are similar
to the base paper used in traditional silver-halide photographs. This gives
your prints the look and feel of traditional photographs, which is important
to most people.
The part that differs is
the image coating. The type of coating determines the performance of your photographs
in terms of air-fade resistance and output print speeds. Printers that output
quickly require media that absorbs the ink fast, as well as dries fast. Such
media are made with porous coatings and sometimes touted by manufacturers as
"instant-dry prints". As the name suggests, the coating consists of
fine particles glued together in such a way that there are air spaces or pores
in between them. These air spaces are later filled with ink, and subsequently,
dyes as the water evaporates. However, because of this structure, porous media
is especially susceptible to air fade. Canon's Photo Paper Pro and Epson's Semi-gloss
photo paper are examples of such media.

Stage 1: When inks
meet porous media
|
Stage 2: How the ink
dries on the porous coating |
Swellable or non-porous
media, on the other hand, has consistently demonstrated resistance to air fade.
The name comes from the coating's ability to swell to two or three times the
original thickness as it absorbs the ink. After the coating has absorbed all
the ink, the coating dries and returns to its original thickness while encapsulating
the ink. HP's Premium Plus Colorfast paper and Epson's Colorlife paper are examples
of such media.
Stage 1: When the
inks are introduced to swellable media |
Stage 2: The swellable
coating reacts with the inks |
Stage 3: After dry
time |
Tips for long-lasting
memories
As you may have guessed,
there's no getting away from light fading unless you're determined to hide
your pictures in a box all through their life--which pretty much defeats the
purpose of having printouts to show off your memorable moments. Resistance
to light fading has nothing to do with the various image coatings. In fact,
according to Henry Wilhelm (of Wilhelm
Imaging Research), coatings do little to affect light stability of the
inks and can even harm the stableness.
While manufacturers often
test their inks with a variety of media--sometimes called a "crepe set"
in the industry--performance is generally best with its own premium-quality
sheets. Therefore, if you like long-lasting prints, you may have to buy printers
based on Epson's pigmented inks or one of HP's 6- or 8-color units together
with the manufacturer's own recommended media. For instance, HP's 5x series of 4-color solutions last
significantly less than the rated 73 years even if used with its premium colorfast
paper. This is because it does not make use of the HP58 photo cartridge which
consists of a much more stable ink. The same applies for HP's newer Vivera inks. The 4-color combination lasts 82 years compared to the 108 years that is accomplished with 6- or 8-color setups.
If you like fast prints,
your prints will last up to 27 years--if you take good care of it. As the
paper media is susceptible to air fade, it may be in your best interest to
frame your photos up. The glass will aid in reducing the amount of air, and
hence the agents that contact the dyes in the pores of the image coating.
Also, using porous media on any printer doesn't automatically mean faster
speeds, and could even cause more problems with some models. Printers are
tweaked with certain ink loads to produce the high chroma required for bright,
saturated outputs. As such, using porous paper on an incompatible unit with
high ink loads will have the result of photos that take a long time to dry.
Finally, although swellable medias seem to have the upper edge with regard to longevity, there are drawbacks. The manufacturers sing the same wonderful tune for swellable coating. However, they also fail to mention the problem that occurs in high-humidity areas (read: most of South-east Asia). Because of the media's nature to draw moisture under its coating, this could present some problems with ink loads. HP, on its part, bundles in a "Ziplock" bag for the media to reduce the paper's exposure to moisture. Epson, on the other hand, does not bring in their swellable media into this region.