Page No 6
Spray Gun Paint Patterns
Faults and Remedies
Top Heavy Spray
Cause
a)
Wing holes partially obstructed
b)
Damaged or obstruction of material
nozzle tip
c)
Air cap or material nozzle not seating
correctly due to dirt or damage
Faulty Spray Patterns
Bottom Heavy Spray
Cause
a)
Wing holes partially obstructed
b)
Damage or obstruction to bottom of
material nozzle tip
c)
Air cap or material nozzle not seating
correctly due to dirt or damage
Remedy
Turn the air cap through 180
°
. If defective pattern is reversed, fault is
due to air cap
Remove and clean air cap
If defective pattern does not reverse then fault is with the material nozzle
Remove nozzle and clean
Do not use metal objects to clear holes
Cause
a)
Dirt in material nozzle or a loosely fitted
nozzle/air cap
b)
Dried out gland packing around
material needle valve
c)
Loose fitting nut or fractured feed tube
in container
d)
Insufficient material in container
e)
Obstructed fluid passageways
Remedy
a)
Clean and refit tightly
b)
Lubricate and tighten (if
necessary
replace
gland packing)
c)
Tighten or replace
d)
Replenish material
e)
Clean
Spitting
Cause
a)
Air hole in either wing of air cap restricted
or blocked allowing full pressure of air on
the other side to force the spray pattern in
direction of restricted or blocked side
b)
Material nozzle tip damaged or having
particles of dirt or dried paint on one side
Remedy
As above
Do not use metal objects to clear holes
Air in material
passages
Correct Spray Patterns
The spray pattern is
variable from round to fan
with all patterns in
between
Cause
a)
Too high an
atomising
air pressure
b)
Attempting
to obtain a
too wide fan
spray with
thin material
Remedy
Reducing air pressure will cure
cause (a)
To correct cause (b) open
material control to fully open
position. At same time reduce
width of spray pattern
If material is being pressure fed,
increase pressure on container
to give increased material flow
Cause
A fan spray pattern that is heavy in the
middle or a pattern that has an
anatomised “salt & pepper” effect
indicates too low an atomising
pressure
Remedy
Increase air pressure from your air
supply. Correct air pressures are
discussed elsewhere in this booklet
Cause
Dried material around nozzle tip
restricts the passage of atomising air
at one point through the centre
opening of air cap and results in this
pattern being obtained. Can also be
caused by a loose fitting air cap
Remedy
If dried material is causing
the trouble, remove air cap
and wipe off material tip,
using a rag wetted with
thinners
Tighten air cap