Principle of Operation
The following discusion outlines the features and principles of operation of airbrushes and sprayguns. For airbrush tanning, our overwhelming
recommendation is the TurboAir Turbo Speed airbrush. It is faster, more comfortable to operate, and easier to maintain than other tanning airbrushes:
TurboAir Turbo Speed Airbrush
All airbrushes work on the same principle; air and fluid meet at an exact point
in space. At that point in space there is a tapered "needle" that projects the
combined air and fluid forward. Fine line spraying requires very delicate
needles tapered to a delicate point. The finest detail airbrushes have a nozzle
size of .18mm. Large commercial spray guns, such as those used for automotive
painting, have blunt needles that do not have much of a taper. The nozzle is
the part of the airbrush head assembly in which the needle rests. It is tapered
exactly the same as the needle it holds. On a single-action airbrush, when the
screw is twisted, it widens the space between the needle and nozzle by moving
the nozzle. In a double-action airbrush, when the trigger is pulled back, it
moves the needle back as well. The farther back the needle moves, the larger
the space between the needle and nozzle.
Atomization refers to how finely the particles being sprayed are broken
apart
Single-Action vs. Dual-Action Airbrushes
"Single-action" and
"dual-action" refer to the way the air and fluid flow of the airbrush is
controlled.
Single Action means that it sprays much like an aerosol can: just push
down the trigger to get it to spray. The trigger controls only the air flow.
When the trigger is depressed, a pre-set amount of fluid is sprayed. The amount
of fluid is regulated by turning the needle adjustment screw at the back of the
handle, or in case of an external mix air brush by turning the fluid cap at the front of the air brush.
Dual Action refers to air brushes on which the trigger controls both air
and color (down for air, back for color). The farther the trigger is pulled
back, the more fluid comes out. This simple maneuver allows the artist to
change the width of the line, the range of value and the opacity of fluid
without stopping their hand motion. A double-action airbrush offers much
greater control and is essential when producing fine lines and thick-thin
strokes (the classic "dagger stroke").
Internal Mix indicates that air and fluid mix inside the air brush. Air
and fluid come together inside the head assembly to produce a thoroughly
atomized fine dot spray pattern.
External Mix indicates that air and fluid mix outside the air brush. Air
and fluid come together outside the head, or fluid assembly. External mix air
brushes produce a larger dot spray pattern than internal mix air brushes. The
amount of fluid that comes out is controlled by twisting a knob or screw
located near the tip. This type of airbrush is also referred to as an
"external-mix," because the air and fluid actually mix in front of the needle.
There are fewer moving parts that need cleaning, therefore it is an easy
airbrush to maintain.
Siphon-Feed Vs. Gravity-Feed Airbrushes
These terms refer to how fluid
is supplied to an airbrush. Although this feature does not directly influence
how an airbrush performs, it does indicate the fluid capacity allowed before
refilling. Siphon-feed means that the color-cup attaches from underneath or to
the side of the body of the airbrush. Air suction pulls the fluid from the cup
to the nozzle area, where it comes in contact with the air.
Bottom Feed refers to air brushes on which fluid enters through a siphon
tube or color cup attached to the bottom of the air brush. Removable jars or
various size color cups can be connected to and utilized with bottom feed air
brushes. This configuration is generally more versatile and enables the user to
change colors quickly.
Side Feed refers to air brushes on which a small color cup fits into the
side of the air brush. The side feed color cup rotates enabling the user to
work on either a horizontal or vertical surface. The side feed configuration
also permits the user to achieve fine detail without the possible sight
obstruction of a top mounted color cup
Gravity Feed refers to air brushes with top-mounted color cups in which
gravity draws fluid into the air brush. Less air pressure is required enabling
slower hand movement which creates excellent control for fine detail
applications. Because the fluid is in an open color-cup, some models offer a
separate cap to keep fluid from drying out in the color-cup. They have a tiny
hole in the center of the cap to prevent a vacuum from developing. It is
essential that this hole be open to maintain proper fluid flow.
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