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HOW DOES YOUR SPRAY GUN SHAPE UP?

No matter how experienced the sprayer, merely
triggering and moving a gun in space will not
reveal any of the performance characteristics vital
to a top quality finish. A simple brief static spray
pattern test will immediately highlight any
potential problems before the gun is used on the
painstakingly prepared workpiece or vehicle.

Follow the procedure explained below and
compare the pattern to our examples. If your
result resembles the examples then look at the
corrective measures before you apply paint to the
workpiece.

(1) Ensure that you have the correct Air Cap, Fluid
Tip and Needle set-up on the gun to match the
material being applied.

(2) Tape a piece of brown paper (approx. ½ metre /
20” square) onto the spray booth wall at shoulder
height.

(3) Having set the gun at the recommended inlet or
atomising air pressure, hold it at he correct target
distance and spray at the paper without moving the
gun.

Normal Pattern – Ready

to Spray

Intermittent Spray Fan or

Fluttering

Good balance and uniformity

?

 

Symmetrical pattern shape

?

 

Good working height and

width

?

 

Uniform distribution of

material (Verify by
horizontal spray-out)

?

 

Air in the fluid passageways

?

 

Insufficient paint in the cup

?

 

Fluid tip loose

?

 

Fluid needle packing or packing

screw loose

?

 

Cup vent hole clogged

Banana Pattern

Heavy Top or Bottom

Pattern

?

 

Air cap horn hole dirty or

damaged

?

 

Test spray pattern, rotate

180

o

 and test again to

isolate horn hole cause
location

?

 

Clean air cap thoroughly

?

 

Replace air cap if necessary

?

 

Fluid tip or cap dirty or

damaged

?

 

Test spray pattern, rotate 180

o

and test again to isolate cause.

?

 

Clean both items thoroughly

?

 

Replace Fluid tip or Air cap if

necessary

Single Split Pattern

Centre Heavy Ellipse

?

 

Too much air for fluid

quantity used

?

 

Reduce air pressure at

regulator

?

 

Increase fluid flow by

changing fluid tip size
opening needle control
knob

?

 

Bad air or paint setting

?

 

Viscosity too high – thin with

solvent

?

 

Fluid flow too high – reduce

?

 

Air pressure too low – increase

Double Split Pattern

Ball End Heavy Pattern

?

 

Too much air for fluid

quantity used

?

 

Reduce air pressure at

regulator

?

 

Increase fluid flow by

changing fluid tip size or
opening needle control
knob

?

 

Too much fluid flow

?

 

Change fluid tip for smaller size

?

 

Reduce flow using fluid needle

control

?

 

Reduce fan size using fan

control

STATIC PATTERN TEST

Having examined the vertical spray pattern for uniformity of shape and size, now turn the air cap through 90

o

 and static spray

a horizontal pattern making sure you trigger for long enough to load the shape with material. Then watch to see the formation
of the run-outs of material across the full width of the spray pattern.

This will highlight how well the material is distributed throughout the spray pattern. If the run-out is more obvious at the

centre or at the ends then this indicates a problem.

TYPICAL GOOD PATTERN RUN-OUT

TYPICAL BAD PATTERN RUN-OUT

Summary of Contents for JGA

Page 1: ...cap horn hole dirty or damaged Test spray pattern rotate 180o and test again to isolate horn hole cause location Clean air cap thoroughly Replace air cap if necessary Fluid tip or cap dirty or damaged Test spray pattern rotate 180o and test again to isolate cause Clean both items thoroughly Replace Fluid tip or Air cap if necessary Single Split Pattern Centre Heavy Ellipse Too much air for fluid q...

Page 2: ...ful if inhaled or if there is contact with the skin Follow the requirements of the Material Safety Data Sheet supplied by your coating material manufacturer Adequate exhaust must be provided to keep the air free of accumulations of toxic materials Use a mask or respirator whenever there is a chance of inhaling sprayed materials This mask must be compatible with the material being sprayed and its c...

Page 3: ...anges with cap movement the condition is in the air cap Heavy centre pattern Too much material Material too thick Reduce fluid flow by turning fluid needle adjusting screw clockwise Reduce fluid pressure or increase atomisation pressure Thin Intermittent or fluttering spray fan Loose fluid tip Fluid tip not seated correctly in gun head Gun with cup tipped at excessive angle Obstructed fluid passag...

Page 4: ...aterial too thin Gun tilted on an angle Adjust gun or reduce fluid pressure Mix properly or apply light coats Hold gun at right angle to work and adapt to proper gun technique Thin sandy coarse finish drying before it flows out Gun too far from surface Too much air pressure Improper thinner being used Check distance normally 6 8 Reduce air pressure and check spray pattern Follow paint manufacturer...

Page 5: ...MAINTENANCE TROUBLESHOOTING PAGE 4 MAINTENANCE TROUBLESHOOTING PAGE 4 ...

Page 6: ...alve and thorougly clean valve shaft and seating surfaces Replace A Gun spits paint when triggering on due to paint build up inside air cap between spraying operations Fluid tip not fitted correctly in gun head Fluid tip needle leakage Tighten to correct torque Check for damage or blockage B Slow fluid leak from fluid tip and needle seat Fluid Tip internal seat scored damaged or worn Fluid needle ...

Page 7: ...lve and thoroughly clean E Stiff trigger action Air valve stem bent Contamination on air valve stem Contamination on trigger bearing screw Contamination on fluid needle shaft Fluid needle packing too tight Replace damaged component Remove and clean Remove and clean Remove and clean Loosen packing nut F Air leak from fluid needle exit point in top of handle Seal damaged or missing Replace G Air cap...

Page 8: ...ent and air discharge is clear Allow air to dry passages and then shut air valve at hose cleaner Repeat with hose to cup or tank connected to hose cleaner Lid on cup or tank should be set to one side of the shell or on a waste container Note This cannot be done with a pump Pump must be run with proper solvent to clean Clean inside of container and lid Wipe down gun with cleaning solvent dampened r...

Page 9: ...air cap retaining ring and gun air baffle threads are free from damage a smear of Vaseline on the threads will help prevent binding 2 Check air baffle seal is not leaking air badly or visibly damaged Replace if necessary 3 Apply smear of Vaseline to needle shaft front end for smooth operation 4 Apply Vaseline to needle shaft rear end and needle spring to aid corrosion and contamination resistance ...

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