Powder Coatings Troubleshooting Guide

PPG is a global leading provider of coatings, paints and specialty materials, offering solutions in every major technology platform, including powder, liquid, electrocoat, pretreatment, as well as advanced energy curable solutions.

This Powder Coatings Troubleshooting Guide explores possible causes and solutions of errors that can occur in the powder application and finishing process. Please contact your local PPG representative for troubleshooting guides on other coatings technologies.

Click Here to Download Full Powder Coatings Troubleshooting Guide with Images

The tips and techniques described herein are based upon the best information and practices known to PPG Industries, Inc. (“PPG”). Any statements or methods mentioned herein are general suggestions only and are not to be construed as representations or warranties as to safety, performance, or results. Since the resolution of issues is highly dependent on the product user’s processes, operations, and numerous other user-determined conditions, the user is solely responsible for, and assumes all responsibility, risk and liability arising from, the determination of whether the proposed solution is suitable for the user. Continuous improvements in coatings technology may cause future technical data to vary from what is in this bulletin. Contact your PPG representative for the most up to date information.

How to fix air percolating issues while powder coating

No air is percolating through the powder surface.

Potential Cause	Solution Proposal
Insufficient air pressure	Check Air Supply Increase air regulator pressure
Compacted powder	Check air line size to equipment Fluidize the powder with clean/dry air
Fluid bottom defect	Replace fluid bottom
Fluid bed clogged	Clean fluid bed

How to fix plugged powder coating hoses

Hoses and pumps are plugged from impact fusion.

Potential Cause	Solution Proposal
Normal build-up / routine maintenance not being done	Clean or replace parts Set standard procedure for maintenance
Air pressure too high	Use lower air pressure settings on powder gun and transfer pumps
Moisture in compressed air supply	Check compressed air supply for clean, dry air
Powder is too fine	Adjust virgin / reclaim mixture

How to fix powder feed to gun

Insufficient or inconsistent powder feed to gun.

Potential Cause	Solution Proposal
Powder not fluidizing properly	See Fluidizing Bed section in downloadable guide
Insufficient air pressure or volume	Check air supply for obstructions to increase the air pressure Check air supply lines for proper size Check equipment specifications Increase atomizing air pressure
Obstruction in powder supply	Check and clean pick-up tubes, pumps and hoses Check sieve screen for tears and proper operation Check powder supply for foreign materials
Hoses kinked, crushed or too long	Replace deformed hose Avoid sharp bends Hoses should be as short as practical
Worn pump venturies	Replace worn parts Set standard procedure for maintenance

How to fix build-up up on the powder coating spray nozzle

During powder coating application, powder or effect agent accumulates at the nozzle slot

Potential Cause	Solution Proposal
Wear of the nozzle wedge	Check or change wedge
Powder output too high	Reduce powder quantity
Powder too moist	Check compressed air and application room for high moisture/humidity
Effect powder coating: electrostatic charge too high	Remove discharge rings
Effect powder coating: incorrect powder hose	Use grounded hose material

How to fix poor charging, low film build, insufficient wrap

Recommended layer thickness cannot be achieved; uneven coverage of the component.

Potential Cause	Solution Proposal
Low or no voltage at electrode	Check for voltage at electrode, cable and power supply Replace missing or broken electrodes Clean build-up from electrodes
Poor ground	Check ground from conveyor through hanger to part; adequate ground is less than 1 mega ohm Remove any build-up of insulating materials from conveyor and hangers
Powder delivery too low	Increase powder flow
Effect powder coating: electrostatic charge too high	Remove discharge rings
Powder output from guns too high reducing the charging efficiency	Decrease powder output from guns until material is properly charged
Humidity too low (in case of Corona spraying)	Control humidity to the proper specification for your system (40-60% RH)
Powder too fine	Adjust virgin / reclaim mixture

How to fix poor penetration

The powder will not coat in Faraday cage areas.

Potential Cause	Solution Proposal
Voltage: Intensity (µA) too high	Reduce Intensity (µA) so that powder builds on edges evenly and does not repel corners
Powder / air velocity too high	Reduce air pressure so that powder does not blow out of recesses
Powder delivery too low	Increase powder flow
Improper technique or gun placement	Adjust gun so that powder is directed at surfaces adjacent to the corners
Improper spray pattern	Select different nozzle or deflector See your equipment manufacturer
Powder too fine	Adjust virgin/reclaim mixture
Part is too close or too far from spray gun	Reduce or increase distance

How to fix powder repelling from part/not sticking to part

The powder does not adhere to the surface or it partly falls away.

Potential Cause	Solution Proposal
Poor ground	Check contacts and hooks Check for adequate ground
Charge too low	Increase voltage
Powder output too high	Reduce powder output
Powder too fine	Adjust virgin / reclaim mixture
Fluidity too high	Contact the powder coating supplier
Film thickness too high	Reduce film thickness
Blow-off effect due to too much conveying air or insufficient distance to the part	Reduce air settings Increase distance to part

How to fix poor powder coating spray pattern

The powder does not adhere to the surface or it partly falls away.

Potential Cause	Solution Proposal
Worn gun parts	Replace worn nozzles, deflectors and electrode sleeves
Blockage from impact fusion	Clean any impact fusion from parts; set standard procedure for maintenance
Hoses, pumps, pick-up tubes or guns clogged	Check/clean hoses, pumps, pick-up tubes and guns Check compressed air for sufficient dryness Control humidity to the proper specification for your system

How to fix fluctuating layer thickness or uneven coating thickness in powder coating

Irregular layer thickness on the component that is visible or only measurable.

Potential Cause	Solution Proposal
Poor grounding	Check hooks and clean if necessary Measure grounding
Irregular powder output	Check fluidization, powder hoses and tab nozzles
Irregular manual application	Train staff or seek additional training on powder coating application
Automatic application: irregular gun spacing, incorrect stroke setting, wrong sine curve, etc.	Measure and adjust distances between guns Adjust stroke Optimize sine curve of automatic guns

How to fix powder lump formation / agglomeration in the cardboard box

Lump formation in the cardboard box or fluid container.

Potential Cause	Solution Proposal
Storage Temperature and humidity at storage location too high	Reduce storage temperature Sieve powder coating
Temperature and humidity during transportation too high	Check powder for humidity Observe temperature during transportation
Pressure during storage too high	Do not stack powder bags in storage
Powder is past expiration date	Use new material
Conveying from cardboard box	Use vibrating floor only when necessary
Poor quality powder coating	Contact powder coating supplier Avoid using low quality powder coating

Additional questions or concerns?

Please reach out to your local PPG representative for additional guides on other technologies. Or download our full guide, including tips for powder surface defects here. For assistance with your order, reach out to us via our chat window or contact us.