OPTICAL
BRIGHTENERS
Optical Brightening Agents (OBAs) or Fluorescent
Whitening Agents (FWAs)
are fluorescent dyes that absorb light in
the UV region of the
electromagnetic spectrum and re-emit light in the blue or blue-violet region.1
“These chemical compounds create a visual whitening or
brightening effect when exposed to near ultraviolet radiation by virtue of
fluorescence, i.e. the conversion of invisible ultraviolet light into visible
blue light.”2
In laundry detergents OBA’s have largely
replaced bluing. The original
bluing was Mrs. Stewarts Laundry Bluing, which is a colloidal suspension of an
ultra fine blue iron powder in a water solution.3 In human hair care, OBA’s are beginning
to replace blue and violet pigments to enhance grey and silver hair. As is usually the case, pet grooming
formulations follow the beauty industry, and we are starting to see OBAs in pet
shampoos and conditioners.
Example: ShowSeason Bright shampoo.
How are OBAs different from blue and violet
whiteners? Glad you asked
(maybe). Here goes: Whitening Blue
or Violet colorants are pigment that lightly tint the substrate bluish or
violet, which the human eye perceives as white. OBAs increase the emitted light, making the substrate
brighter; the result is whiter whites and brighter colors. These fluorescent whitening agents increase
brightness as well as whiteness.
The fluorescent nature of OBAs is such that they show up under blue
light. For this reason, they are
undesirable for use by the military or hunters as they glow in the dark when
viewed through night vision goggles or by deer4. We might ask why are OBAs desirable. They have replaced bluing in laundry
detergents because they have greater reflectance, fade less between washings
and are effective in very small amounts. They make all colors brighter.
It is important to note that Optical Brightening Agents is a group
of chemicals, not a single substance.
There is a wide range of chemicals available for different applications. The OBAs used for hair care are similar
to those used for cotton fabrics. Two
of these are marketed under the trade name Tinopal: Disodium distykrylbiphenyl
disulfonate* and disodium diaminostilbene disulfonate*. In hair care, OBA’s are
often combined with silicones to increase brightness and shine as well as
reduce yellowing.5 Dow Chemical, a leading silicone developer, has combined the
two into a single cross linked compound, they call “amino functional
organosilicon optical brightener.”6
What’s
true:
·
Optical Brightening Agents,
OBAs, aka Fluorescent Whitening agents, FWAs are chemicals, not to be confused
with natural brightening agents like Awapuhi (Hawaiian White Ginger Root),
chamomile, cornflower extract, etc, or other coat brighteners like phenyl
trimethicone or Amodimethicone, which add shine and sparkle.
·
OBAs originated in the laundry
and papermaking industries and have drifted into the beauty industry in hair
products and makeup. They are used also in plastics manufacture and several
other industries.
·
They work by the use of
fluorescence, specifically the conversion of invisible ultraviolet light into
visible blue light.
·
They are especially good for
reducing the visibility or perception of yellowing and enhancing the appearance
of whiteness.
·
They do not fade as quickly as
whitening agents (bluing) and may actually accumulate (in laundry) over time.
·
They offer the added feature of
protecting the hair from UV damage, since they absorb the invisible UV rays.5
·
In hair care OBA’s are often
combined with silicones to increase brightness and shine and reduce appearance
of yellowing. Dow Chemical, a leading silicone developer, has combined the two
into a single cross-linked substance “amino functional organosilicon optical
brighteners”.
·
OBA’s are used in very small
amounts and have been determined to be safe as used, and are not an
environmental hazard.
·
The only notable downside is
that some individuals (humans) may exhibit an allergic sensivity to OBAs.
What’s
not true:
·
It is absolutely not true that
optical brighteners deposit tiny particles of plastic on the coat. This untruth seems to be an unfortunate
misinterpretation. How could this
have occurred? See below:
o In make-up applications (not hair applications), OBAs are often
present in microspheres as the delivery system. Microspheres gradually dissolve to leave the optical
brighteners on the skin. OBAs are used to diminish the appearance of dark circles
under the eyes and other skin discoloration.
o The term “plastic” in cosmetic chemistry refers to the property of
being moldable or flexible.
Microspheres with OBA’s may have this property.
·
OBA’s are not toxic although
some humans have reported allergic response.
More
about whitening pet coats: The maintenance of white coats involves more than the simple
addition of a brightening agent to a regular shampoo. Please refer to our full article on “Understanding Whitening
Shampoos”. This was written in
2005, prior the appearance of fluorescent brightening agents referred to here
and goes into greater depth. Here
is the dropbox link to the full article. https://www.dropbox.com/s/fg2iovuwftxq5aq/Whitener%20Shampoos.pdf?dl=0
REFERENCES:
1. NPTEL: Textile Engineering - Textile
Processing: Theory & Practice of Preparatory Processes.
2. P&G.com Science in the Box: Optical
Brighteners, Fluorescent Whitening Agents,
3. About.com: Laundry Bluing
4.About.com: Optical Brighteners
5.Hair Care Compositions comprising optical brighteners and silicone
compounds.
6. Dow Corning Patent No. EPO336709A2 Amino
functional organosilicon optical brighteners http://www.google.as/patents/EP0336709A2?cl=en
*Don’t freak out! You can say it. Let’s break it down. Ready? Underlined syllables are emphasized. Dye-soh-dee-um
/Dye sti-rill -bi-fee-nil / Dye-sull-fo-nate, Disodium Distyrylbiphenyl Sulfonate. You’ve got it! Here’s the other one: dye-soh-dee-um/
dye-a-meeno-still-bean/dye-sull-fo-nate, Disodium diaminostilbene disulfonate. Don’t fear chemicals;
just learn to pronounce them!
In addition to owning TRANSFORMATION PET CENTER in Tucson, Arizona, BARBARA BIRD is author of the book Beyond Suds & Scent - Understanding Pet Shampoos & Conditioners. She is also half of The Groom Pod, a weekly podcast for groomers. The Groom Pod can be found on iTunes, Stitcher, Facebook or www.thegroompod.com.
In addition to owning TRANSFORMATION PET CENTER in Tucson, Arizona, BARBARA BIRD is author of the book Beyond Suds & Scent - Understanding Pet Shampoos & Conditioners. She is also half of The Groom Pod, a weekly podcast for groomers. The Groom Pod can be found on iTunes, Stitcher, Facebook or www.thegroompod.com.
Excellent post! This is an in-depth and detailed description about Optical Brightening Agents (OBAs)/FWAs. It was helpful in understanding and uncovering some untruths that are generally associated with whitening agents.
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