Possible causes



Crispy film: Finished coating surface showing cracking texture with crispy coating layer 

Powder is not well cured.

Increase curing temperature or extend curring time or both.


Powder clogging/lumping

Storage temperature too high.

Powder exposured to high humidity environment.

Powder is stressed under high force.

Move the powder to the proper temperature and dry area.

Avoid heavy force above the powder while storing.



Contaminated with other powder.

Inadequate pretreatment of coating subtrate.

Contamination with incompatible materials from the spraying area.

Compressed air infected with oil, moisture, wax or silicon residues.

Clean the spraying system and start with the virgin powder.

Check pretreatment process.

Check the spray area for presence of incompatible materials.

Check compressed air line and air filter.


Off color coating (Color difference)

Oven temperature too low or too high.

Baking time in the oven too long or too short.

Improper oven exhaust

Variation in film thickness.

Coating itself.

Adjust the oven temperature.

Review the baking schedule from the powder supplier, adjust the oven temperature or conveyer speed.

Check the exhaust ventilating fan.

Manage consist film coating.

Clean application equipments thoroughly while changing color.

Contact powder supplier.


Orange peel: The smoothness’ too poor and look like Orange-peel

Improper film thickness.

Air pressure too high.

Incompatible powder contamination

Micro -pinholding from gassing.

Bad powder free-flow properties.

Adjust the film thickness as per recommendation from powder supplier.

Cease the air pressure on the spraygun control unit.

Clean application equipment before changing powders.

Check substrate for porosity.

b. Check substrate for moisture.

c. Check powder for moisture from reclaim or compressed air.

d. Check film thickness, coating too thick.

Contact powder supplier


Poor adhesion of cured film

Inadequate cleaning or pretreatment of subtrate.

Undercured coating film

Check the pretreament process.

Increase oven temperature or oven dwell time


Poor powder penetration into recessing area or deep corner due to Faraday cage.

Poor powder delivery.

Poor ground.

Improper spray pattern.

Voltage too high or too low.

Powder output too high or the

pressure for the transport air too high, which blows the powder from the object.

Poor gun positioning.

Powder particle size too fine or too coarse.

Improve Powder delivery.

Check ground from conveyor rail (or rub bar when used ) through hanger to part. All contact areas must be free from heavy grease and other insulating material

Select proper deflector or spray nozzle.

Adjust Voltage settings.

Turn air pressure on pumps and guns to the proper setting.

Turn the spraygun into right position so that powder builds on necessary area.

Too much reclaim added to

virgin powder. Or contact powder supplier for assistance.


Poor impact resistance / poor flexibility

Undercured coating film.

Poor cleaning or pretreatment.

Too heavy coated film.

Coating substrate changed

Uneven formation of the phosphate layer and residues from the pre-treatment.

Improve baking schedule.

Check pretreatment process.

Reduce film thickness.

Consult with powder supplier

Check the surface pretreatment


Gloss too low for High gloss powder or Gloss too high for Matt powder

Virgin powder contaminated.

Overcured or Undercured.

Defective spray equipment.

Moisture in the compressed air might kills the gloss

Clean application equipment before changing powders.

Adjust curing oven setting.

Check with spray equipment supplier.

Checking compressed air filter.


Yellowing: The color is yellower than standard color.

Too high baking temperature or baking duration too long.

Different in coating film thickness.

Suitable baking condition should be ensured.

Adjust the film thickness evenly.


Pinhole: Tiny holes appear on the coating surface after curing.

Compressed air infected with oil, moisture, wax or silicon residues.

Moisture remains on the metal substrate

Porous substrate

Check compress air quality, clean air filter system.

Dry out metal substrate before coating.

Using appropriate powder coatings which are especially designed for diffusing gas on the coating surfaces.


Bits: Small sand dots defect.

Foreign materials that does not melt and flow out during curing process.

Failure on the substrate cleaning.

Check the contamination issue from powder, conveyor chain, spray booth and curing oven.

Check the pretreatment process to make sure the prepaired metal surface is totally cleaned.

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