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University Research
Research Study Shows That Hand
Washing of Cars
at Home is Harmful to Automobile Finishes
The International Carwash Association working through a special Carwash
Research Foundation Grant to the University of Texas at Arlington, Texas,
has conducted extensive car washing tests to determine the effect on car
finishes by comparing various car washing techniques ranging from
professional car washing to the bucket and sponge used by many auto
owners.
Hand
washes are extremely harmful to automobile finishes
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Tests conducted by the University of Texas to compare surface
disturbances showed that a single home hand wash on an automobile can
produce scratches that penetrate as deep as 1/10 of the total thickness of
the automobile's paint.
These test
findings at the University of Texas substantiated tests done over ten
years ago by the Technical University of Munich, Germany, in association
with Mercedes-Benz, which at that time showed that similar damage was done
to an automobile when using detergent, low water volume commonly found in
hose nozzles at home, buckets of water, sponges and towels used in the
average home car washing.
Specific
scientific tests at the University of Texas further showed that hand car
washing can produce so many marks on a car's finish that they cannot even
be counted. The tests showed that in all hand washing temperatures,
surface reflectance readings steadily declined, with some hand washing
techniques being considerably worse than others. By contrast, when cars
were washed by professional full service car washes, there was virtually
no change in the surface reflectance or shine readings.
The tests showed
that the average backyard hose is not able to supply enough water along
with the detergent action to avoid damaging the car's finish. The most
harmful method of washing cars was found to be the special "car wash"
brushes that hook on to a garden hose and are purchased from local
hardware stores or automotive supply dealers. The use of this type of
brush with the low water pressure that comes out of the garden hose is the
most destructive on the finish of an automobile. The tests also showed
that techniques used at professional car washes are virtually harmless to
automobile finishes. Findings from the University of Texas research study
indicate that with the large amounts of water and specialized detergents
used in professional car washes, sophisticated gloss and reflectance meter
readings from new finishes used on automobiles were virtually the same
before and after the equivalent of several months of normal washings in a
professional car wash.
The professional car wash is able
to provide and use tremendous amounts of water along with specialized
detergents and appropriate mechanical action from cloth pads and curtains
which the backyard hose and bucket hand car wash is not able to supply.
This important and interesting research study performed by the University
of Texas found that today's automobile owner is much wiser to have their
car washed by a professional car wash, rather than washing it at home in
their own backyard.
The Technical
University of Munich has carried out an impartial scientific comparison
test in association with Mercedes-Benz to establish the exact ranking of
hand washing versus machine washing of vehicles relative to damage to
paintwork.
To make the test
as realistic as possible, typical family sedans were used - with a few
hundred miles on the odometer. It was stipulated that each car was to
receive the equivalent of one year's wash stress (about 25 washes) - some
cars by hand washing methods, others by automatic carwashing equipment.
To make the test
as realistic as possible, and to give both the hand washers and the
automatic carwashing equipment something to get clean, five test vehicles
were thoroughly coated with a mixture of street dirt, under-fender dirt
accumulations, oily water, and thawing-salt residue. This test mixture,
inspected under a microscope, contained grit particles measuring between
0.5mm and 1.0mm which are enough to damage the toughest paintwork if not
carefully removed.
The Hand Wash
Without having
been told the why's or the wherefore's, four men were given the chore of
washing four of the test cars by hand. Each person was to do as thorough a
job as possible. Since there were four people involved, and since each
person used their favorite "tools", together they presented a
cross-section of various hand washing techniques commonly used by average
car owners.
So the marathon
carwash began. The four men showed up in four different sections of town
enthusiastically sponging and lathering their test cars as if they were
their very own. Bystanders could see one man hard at work in a
do-it-yourself self-service type of car wash with high-pressure water
facilities; another was busy at home with the garden hose and a water
spray-brush. One man scrubbed away utilizing a bucket, a sponge, and a
garden hose. One, to the horror of the environmentalists, and in defiance
of local regulations, washed his test car at a lakeside.
The Automatic Wash
As the
alternative to the perspiring hand washers, automatic carwashing equipment
was used to wash the fifth test car. To keep the test above board, the
test vehicle arrived unannounced during the hours when the car wash was
open for business. The car was washed along with other cars.
The Examination
To measure the
extent of paintwork damage, microscopes were available. However, pure
reflecting microscopy, as well as electron microscopy results merely in a
visual picture of scratches. A comparable measure of true depth cannot
thus be achieved. Consequently, a method of analysis was used which could
determine the exact depth of the scratches and grooves, namely, the
interference-microscopic analysis method.
This method
allows the glossy surface, with all of its irregularities to appear like a
relief map. An interference band is created and corresponds to the
contours. Band distances are 0.27 of one thousandth of a millimeter,
thereby allowing even the tiniest grooves and scratches on the gloss to be
accurately measured and compared.
The Result
The comparison
tests produced results of which every car owner should be aware. Automatic
car washing and hand washing have completely different effects on
automobile paint.
How does the
paintwork of a car appear after 25 washes - equivalent of a year's worth
of washing?
The results are
depressing, at least to the car owner who, up to now, has firmly believed
in hand washing. The deepest scratches after hand washing had a depth of
more than one-tenth of the paint surface. Under the microscope, the
paintwork looked like a cratered landscape. The paintwork was deeply
scored and scratched - the result of dirt and trapped sand particles.
In hand washing, invariably too
little water is used. Even with a garden hose and a sponge technique,
small sand particles lodge themselves firmly in the fine pores of the
sponge or wash mitt and cannot be removed even by good rinsing. Such
particles work on the paint surface like sanding discs. Furthermore, the
hand washings produced a tangle of uneven scratches in the paint surface.
By comparison,
the surfaces of the test vehicle washed with automatic carwashing
equipment appeared different. Compared with the hand washed surfaces, it
was remarkably smooth, with many very fine markings virtually parallel and
uniform - less than .0003mm - the result of evenly moving and rotating
cloth pads and curtains. The machine-washed surfaces were in very good
condition after 25 washes.
Wash a car by
hand or by machine, in either case, it looks immaculate right after the
wash. The sophisticated test described suggests that looks are deceiving:
The paintwork on a car washed by automatic carwashing equipment is in much
better condition than one washed by hand - even though the car owner
lavishes tender, loving care on their vehicle.
Eventually,
either by force of habit or because the car finish looks dull, the weekend
hand washer resorts to the lengthy and back-breaking chore of applying
abrasive rubbing compound or similar pastes and liquids to their vehicle.
This process indeed restores the luster to the finish. Such "pampered"
cars naturally appear to have just rolled out of the showroom. The proud
motorist forgets the long hours with the rubbing compound, and is probably
unaware that the reason for all that work (to get the scratches out) was
their energetic hand washing procedure on previous weekends.
On the other
hand, the motorist who uses the services of a professional car wash with
their automatic carwashing equipment subjects the paintwork of their
vehicle to the thorough, but gentle action of cloth pads and curtains
which treat their paint job with tender, loving care. Knowing that the car
finish has to have some protection against the ravages of the chemicals in
the air and to also provide a barrier of protection against bird droppings
and other contaminants, this car owner will periodically apply a coat of
wax to their vehicle. At that moment, their car looks as if it had just
rolled out of the showroom.
In comparison, although both cars
after washing and other treatment will look pretty much the same, a car is
actually treated better (especially concerning the paint finish) by
machine washing at a professional car wash and the application of wax than
a car washed by hand (with the resulting need for the application of
rubbing compounds, etc.). However, in the process, the car owner who
utilized the services of a professional car wash has saved a great deal of
time, labor, and effort. |
