When
Good White Goes Yellow
Believe it or not,
there's a lot of science that goes in to making
and selling a white garment, and keeping it
white. It might seem like the easiest
thing of all -- no dye, no pattern, no problem,
right? That's where you'd be wrong.
The white that we
all prize in a garment, be it a shirt, skirt
or gown, is not really a naturally-occurring
color. It has to be helped
along to be that white.
For instance, have
you ever bought a garment that was slightly
off-white, and seen the words, "Natural Color"
on the label? The fibers themselves have
not been bleached or enhanced in any way to
make the white any whiter than it normally appears.
But when only the brightest will do, Mother
Nature gets some help from eager beaver chemists.
What
is White?
You may remember back
to your school science classes and recall that
what we see as "white" is actually a blending
of all the colors of the spectrum. And
there's no such thing as just "white."
If you don't believe that, compare the
sheet of the paper your news is printed on with
a piece from a copy machine or a laser printer.
Suddenly one looks VERY white, the other looks
dingy and yellow.
All
Lights Are Not Created Equal
One of the things that
has a huge impact on your perception of color
is the light you see an object under.
Ever come out of a mall in the evening when
the parking lot lights are on and almost not
been able to find your car because it looks
so different in that light? There
are differences between household lights (incandescent
lights), office lights (fluorescent lights)
and good old sunshine, too.
Household lights tend
to bend light toward the yellow and orange end
of the spectrum, and away from the blue end.
That means that even the brightest white will
look a bit yellow under such lights. Fluorescent
lights, on the other hand, bend the light toward
blue, so whites look whiter (actually, more
blue) under them. Amazing how many stores
have fluorescent lights... or is it? Sunlight
varies with the time of year, atmospheric conditions
and time of day, of course.
Optical
Brighteners
But back to your white
garment.... When the fiber was in its
natural state, it was probably bleached, and
other things were added, too. One might
have been an Optical Brightening Agent (OBA).
This is a chemical
that actually absorbs ultraviolet light and
radiates it back as light in the spectrum at
the blue end, so that whatever it is on appears
brighter white. OBAs are
found in detergent mixtures you buy and use,
as well as on textiles and on paper (remember
that photocopier paper experiment?) When
it comes to textiles, however, OBAs can eventually
be removed by cleaning or washing.
So
Why Is My Shirt Yellow???
According to the experts
at Cotton
Inc., there are several possible culprits:
- The
fibers of the garment degraded.
Excessive heat, exposure to light, and just
aging of the fibers can do this.
- The
whitener goes yellow!
If too much OBA is used, it can yellow over
time, oddly enough. Also, some fabrics
receive a treatment of lubricating oils or
softeners. These can actually attract
dirt and lead to yellowing.
- Pollution.
Even the ozone we're all so concerned about
can lead to yellowing, but so can the gases
from combustion engines, and even natural
pollutants.
- Transferred
contaminants. Storing
clothing in packaging that doesn't "breathe",
or in boxes that are not acid-free, can lead
to yellow areas of a garment. So can
storing a garment for a long time with shoulder
pads in place. That's why such care
is taken in packaging wedding gowns for archival
storage.
- You
did it yourself! Yes,
sometimes you hurt your own clothes, with
the antiperspirants, perfumes and body lotions,
or make-up, medical ointments and even laundry
products you use. Even using spray starch
when you iron something can cause a build-up
of cornstarch, which will yellow with age.
So,
what's the bottom line?
Obviously, taking good
care of your clothes is key to extending their
life, with proper cleaning and storage.
But a realistic approach to life is a big help
too. No garment
will last forever, despite the textiles they
dig out of mummy pits on TV.
Do what you can to minimize the potential sources
of yellowing, and let us help with our special
tender loving care.
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