Basic HTML Version
Condition
Cause
Correction
Heavy top or
bottom pattern
Horn holes plugged.
Obstruction on top or bottom of fluid nozzle.
Cap and/or nozzle seat dirty.
Clean. Ream with non-metallic point.
Clean.
Clean.
Heavy right or
left side pattern
Left or right side horn holes plugged.
Dirt on left or right side of fluid nozzle.
Clean. Ream with non-metallic point.
Clean.
Remedies for the top-heavy, bottom-heavy, right-heavy, and left-heavy patterns:
1. Determine if the obstruction is on the air cap or the fluid nozzle. Do this by making a test spray pattern.
Then, rotate the cap one-half turn and spray another pattern. If defect is inverted, obstruction is on the air cap.
Clean air cap as previously instructed.
2. If the defect is not inverted, it is on the fluid nozzle. Clean nozzle. Check for a fine burr on the edge of the fluid nozzle.
Remove with #600 wet or dry sandpaper.
3. Check for dried paint just inside the cap center hole opening. Remove by cleaning.
Heavy center pattern
Material flow exceeds air cap’s capacity.
Atomizing pressure too low.
Material too thick.
Thin or lower fluid flow.
Increase pressure.
Thin to proper consistency.
Split spray pattern
Fluid adjusting knob turned in too far.
Insufficient material flow
Atomization air pressure too high.
Too much fan air.
Back out counter clockwise to achieve proper flow.
Increase fluid pressure (pressure feed)
Reduce air pressure.
Turn fan adjust in to reduce.
Jerky or fluttering spray
Loose or damaged fluid tip/seat.*
Material level too low.
Container tipped too far.
Obstruction in fluid passage.
Loose or broken fluid tube or fluid inlet nipple.
Dry or loose needle packing nut.
Tighten or replace.
Refill.
Hold more upright.
Clean.
Tighten or replace.
Lubricate or tighten.
Will not spray
No air pressure at gun.
Needle adjusting screw not open enough.
Check air supply and air lines.
Open needle adjusting screw.
Excessive overspray
(spray mist)
Too much atomization air pressure.
Gun too far from work surface.
Improper stroking (arching, gun motion too fast).
Reduce pressure.
Adjust to proper distance.
Move at moderate pace, parallel to work surface.
Dry spray
Air pressure too high.
Gun too far from work surface.
Gun motion too fast.
Gun out of adjustment.
Decrease air pressure.
Adjust to proper distance.
Slow down.
Adjust.
Fluid leaking from
packing nut
Packing nut loose.
Packing worn or dry.
Tighten; do not bind needle.
Replace or lubricate.
Fluid leaking or dripping from
front of gun
Foreign matter in tip.*
Packing nut too tight.
Dry packing.
Fluid tip or needle worn or damaged.
Needle spring deformed or broken.
Clean.
Adjust.
Lubricate.
Replace tip and needle with lapped set.
Replace.
Runs and sags
Too much material flow.
Material too thin.
Gun tilted on an angle, or gun motion too slow.
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" (152–203 mm).
Reduce air pressure and check spray pattern.
Follow paint manufacturer’s mixing instructions.
Thick, dimpled finish
" orange peel"
Too much material
coarsely atomised.
Gun too close to surface.
Air pressure too low or too much material.
Improper thinner being used.
Material not properly mixed.
Surface rough, oily, dirty.
Check distance. Normally 6–8" (152–203 mm).
Increase air pressure or reduce fluid flow.
Follow paint manufacturer’s mixing instructions.
Follow paint manufacturer’s mixing instructions.
Properly clean and prepare.
Excessive fog
Too much or too-fast-drying thinner.
Too much atomization air pressure.
Remix properly.
Reduce pressure.
Unable to get round spray
Spreader valve not seating properly.
Air cap retaining ring (nut) loose.
Clean or replace.
Tighten.
*Most common problem.
Troubleshooting
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Troubleshooting