Despite the fact that in modern vehicles, new plastics and composite
materials, are more and more used, steel and aluminum remain the basic materials
for car body construction, 1st and 3rd place accordingly (2nd by volume
material used in cars is plastic).On average, one passenger vehicle contains
about 1000kg of steel, and aluminum
represents up to 9% of weight of all
modern vehicles.
Did you know that the human body contains 4,2g of iron, enough to make a piece of car door 27mm x 27mm?
Therefore, anti-corrosive protection
is still vitally important, since both metals must be treated. Production lines nowadays use galvanization as
the most common method of carbon steel protection. Galvanization is the process
of applying a thin (maximum 20 microns)
zinc coating. In car plants the usual way of application of this coating is by
hot-dip galvanization in which car body is submerged in a bath of molten zinc. Additional
protection is provided by cataphoresis primer or E-coating.
It is worth mentioning that rust
problems depend heavily on the local climate. Cars from cold climates tend to
rust near the bottom, particularly lower door edges and panels subject to salt
used for de-icing. Cars from coastal areas are more prone to rust around the
hood, trunk and upper areas of fenders and doors.
Needless to say that during the car
body repair procedures like grinding or welding, you can easily damage thin
galvanized coating and expose metal to rust. Therefore it is imperative to use
one of the following products to treat those areas:
– Self-etching primer
– Wash
primer
– Epoxy primer
– Polyester putty with rust prevention components
– Direct to metal acrylic primers
The last two products are quite new
in the market of automotive refinishing materials, and are not widely available
yet.
Finally, below there is a nice video
about how to choose the right primer for your paint job:
