For the past several years chemical companies have
been offering the detail industry "citrus cleaners." Just what are
they and are they really anything different than what has always
been used?
In order to understand "citrus cleaners" one has to
understand "d-Limonene." Simply stated, d-Limonene is a solvent
that is extracted from citrus fruit rinds.
A few years ago the juice manufacturers were quite
happy to sell their leftover citrus oils to chemical manufacturers
at reasonable prices because they didn't have much use for it. However,
with the scare that the EPA gave chemical manufacturers when they
planned, a few years back, to eliminate the use of some of the more
common ingredients used in cleaning chemicals, caused chemical manufacturers
to look for other alternatives.
d-Limonene was one of the alternatives. This natural,
safe solvent had many of the cleaning abilities of the more hazardous
solvents but it was environmentally friendly. As a straight solvent
it can replace many undesirable and dangerous solvents such as mineral
spirits; methyl ethyl keton, acetone, toluene, xylene and most of
the chlorinated solvents. It is a great tar and asphalt remover
when combined with a special surfactant. Today it is used in several
different cleaning chemicals.
Solvents
As a solvent, d-Limonene is one of the best. It has
a KB rating (solvency rating test) of 67 compared with others. Mineral
spirits 55; Butyl cellosolve 50 which gives you an idea of the solvency
of d-Limonene. It can easily dissolve and suspend heavy oils such
as tar and asphalt type compounds.
There are some drawbacks in using d-Limonene as a
straight solvent. The major one is odor, too much of a good thing,
so to speak. When used indoors, the orange citrus odor is overwhelming
to many people. If you mist it, the mist is flammable. The flash
point of technical grade d-Limonene is 115 degrees F. So it cannot
be used in many cleaning chemicals.
Some chemicals companies mix it with a flash suppressor
which increases the flash point ot over 200 degrees F.
d-Limonene does not leave any significant residue
and it is non-corrosive to metals. But it will attack some plastics;
rubber; paint and polymers. This is important because seals in high
pressure pumps can be adversely affected by d-Limonene.
d-Limonene as a Cleaning Compound
Now that the chemical industry has turned more and
more to environmentally friendly chemicals such as d-Limonene we
are seeing changes in chemical formulation. There are difficulties
however, because many natural solvents are resistant to solubility
in water. Manufacturers of cleaning chemicals spend many hours in
R&D to develop ways to formulate degreasers with a high percentage
of d-Limonene in it. Another challenge when using d-Limonene as
an additive in detergents is its suppression of the foaming ability
of "foam-making" surfactants. The total percentage of d-Limonene
must be kept under 10% while adding more surfactants to keep the
foam levels up, as customer require.
How d-Limonene Works in Cleaners
Most cleaners do not use soap as part of the cleaning
system. Soap is comprised of what is called tallow mixed with alkaline
material and water. The resulting soap is OK for taking a bath but
terrible for industrial cleaning such as detailing.
What chemical companies do is use surfactants in different
amounts and blends to replace soap. Again, it takes hours of R&D
to arrive at the right combination of surfactants to put in cleaners.
Surfactants are combined with other alkaline ingredients
such as rinsing agents; water softeners; and sequestrants to control
the calcium and magnesium in the water.
Surfactants are the ingredients that penetrate the
dirt and put it in suspension. The surround the oils in the dirt
and don't allow them to reform or stick to the surface again. The
more surfactant in a product, the better the cleaning. Some companies
do skimp on surfactants because they are expensive. Instead they
use cheaper ineffective ingredients that don't dilute well with
water and don't work effectively.
Solvents are added to this surfactant system to attack
the barrier of hydrocarbons, such as oils, grease, tar, asphalt,
fuels, etc. Surfactants do what they can do put them in suspension
for rinsin,but they are not enough to do the job. Alkaline ingredients
work to emulsify them, but only a limited amount can be put in the
product because of the danger of high pH on some surfaces. The solution
then is to add a solvent to do some of the work. As mentioned, many
of the solvents used are not so environmentally friendly so "safe"
natural solvents like d-Limonene provide an excellent alternative.
However, the juice producers have now become aware of the need for
safe solvents and have "jacked-up" the price to more than what are
paid for the less environmentally safe solvents. A case of supply
and demand.
Applications for d-Limonene
Products
Any product containing more than 50% d-Limonene are
considered a straight solvent. They can be used for removing ink;
tar; asphalt; gum; adhesives; etc. The product should be used undiluted
for best results. There are even some products in the market that
contain 90% d-Limonene; a surfactant and a gelling agent. This is
an excellent engine degreaser because it clings to vertical surfaces
of the engine and emulsifies the grease. The typical water-based
degreaser tend to run off onto the ground or evaporate before they
can do the job. Less product is actually used when it is gelled
and sticks to the surface.
Products containing 20% to 50% d-Limonene are where
the engine degreasers used in the detail industry fall. They rinse
welll well because of the amount of surfactants in the formulations.
A product containing an alkaline detergent and 30% d-Limonene makes
one of the best degreasers you could find.
Products containing less than 20% d-Limonene make
up over 8% of the products on the market catagorized as cleaners.
With 5% d-Limonene, alcohol and a surfactant you have a very good
glass cleaner. At 10% it is a great and safe wheel cleaner; upholstery
cleaner and all purpose cleaner.
Remember, d-Limonene at high concentrations can affect
pump seals and rubber parts. You need to use it with sprayers that
have viton seals. An ordinary garden sprayer will last only about
10 minutes if you put d-Limonene in it. And, the typical 32oz spray
bottle has a very short life if used to dispense d-Limonene containing
cleaners.
Safety and Environmental Concerns
d-Limonene is definitely a preferred solvent when
it comes to safety and the environment. It is biodegradeable and
less toxic than other solvents. It is non caustic and non-reactive
to metals. The EPA has classified it as a non-toxic chemical. It
is not regulated by the Clean Air Act.
d-Limonene is a slight skin and eye irritant and in
a mist it can be aggravating to the lungs, but there are no known
long-term effects on humans. It is a noncarcinogenic and non-mutagenic.
Overall, d-Limonene is the premier natural solvent
in use in the cleaning industry.
What to Look for in d-Limonene
Products
Always ask for a copy of the MSDS. Some chemical manufacturers
use less expensive solvents to extend the d-Limonene. They work
OK, but they really aren't what you think you are buying. They claim
to be "safe" or be a citrus cleaner when in actuality they are nothing
more than a typical solvent cleaner that is orange colored and orange-scented
to give the appearance of a cleaner that contains high percentages
of d-Limonene. What you need to know and determine is the percentage
of d-Limonene in the product. Remember color and scent mean absolutely
nothing in terms of a cleaner's real make up. |
