Help
Troubleshooting
Common powder coating problems and how to fix them.
| Problem | Likely Cause | Solution |
|---|---|---|
| Pinholes in cured coat | Moisture in compressed air or powder, film thickness too high, oven temperature too high, substrate porosity | Check for and eliminate moisture in compressed air or powder. Decrease film thickness – use lower voltage, shorter spray time or less dense powder cloud. Reduce oven temperature and/or increase line speed/decrease dwell time. Check substrate for porosity - pre heat to outgas. |
| Blistering or peeling | Contamination under powder | Properly clean and pretreat the substrate. For example, fully degrease with acetone after stripping. Handle with clean nitrile gloves. Check your cure parameters. |
| Orange peel or poor flow | Film thickness too low, back ionization/kV rejection, oven temperature too high, substrate heat up time, improper storage powder storage | Increase film thickness – use higher voltage, longer spray time or denser powder cloud. See application section. Reduce oven temperature and/or increase line speed/decrease dwell time. Adjust oven temperature and/or time. Make sure that the object itself reaches the correct cure temperature for the correct time. Make sure that the powder has been stored in the proper environment. Storage in high temperature or humidity can excessively age powder. |
| Soft or scratchy finish | Under-cure (metal didn't reach temperature) | Cure to metal temperature, not oven air temperature. Allow full cool-down time. |
| Poor adhesion | Under-cured powder, poor cleaning or pretreatment, film too thick or a change in substrate | Run oven profile to determine if recommended time at temperature is achieved, then amend oven temperature or amend line speed or dwell time. Check pretreatment equipment and concentrations, and consult pretreatment supplier. Reduce film thickness by adjusting application equipment. Check substrate with supplier. |
| Color fading over time | Standard polyester on exterior | Use Super Durable (SR) formulation for any surface exposed to regular sunlight. |
| Metallic flakes oxidising | No clear coat over metallic or candy | Always apply a compatible clear coat over metallics and candy finishes. |
| Poor impact resistance or flexibility | Under-cured/over cured coating, poor cleaning or pretreatment, film too thick, change in substrate thickness or type | Run oven profile to determine if recommended time at temperature is achieved, then amend oven temperature or amend line speed or dwell time. Check pretreatment equipment and concentrations, and consult pretreatment supplier. Reduce film thickness by adjusting application equipment. Check substrate with supplier |
| Poor corrosion resistance | Poor cleaning or pretreatment or uder-cured coating | Use Super Durable formulation for any surface exposed to regular sunlight. |
| Poor pencil hardness; poor abrasion resistance | Under-cured | Apply a compatible clear coat over metallics and candy finishes. |
| Chipping | Cure schedule issues, film thickness or poor substrate | Run oven profile to determine if recommended time at temperature is achieved, then amend oven temperature or amend line speed or dwell time. Check pretreatment equipment and concentrations, and consult pretreatment supplier. Reduce film thickness by adjusting application equipment. Check substrate with supplier |
| Impact fusion | Build-up of powder due to inadequate maintenance, too much feed air pressure, moisture in the compressed air supply, or high relative humidity in application area | Check pretreatment equipment and concentrations and consult pretreatment supplier, Run oven profile to determine if recommended time at temperature is achieved; increase oven temperature or decrease line speed/increase dwell time. |
| Not enough powder being fed through hose/pump | Squashed hoses, or kinks in hose line, pump ventures are worn, not enough air pressure | Run oven profile to determine if recommended time at temperature is achieved; increase oven temperature or decrease line speed/increase dwell time. |
| Static (tribo) charging | Low humidity in the application room or inadequate grounding of equipment | Increase oven temperature and/or dwell time & make sure that the object itself reaches the correct cure temperature for the correct time. Reduce film thickness by decreasing spray time and/or air pressure. Ensure parts are properly cleaned and pretreatment system is in good working order. |
| Surging, spitting or interrupted powder flow | Not enough volume or supply pressure of air, kinks in the powder hose lines, pump venturi tubes, hoses or guns blocked with impact fusion, or too much humidity in the powder area | Clean and if necessary, replace wear parts; implement proper maintenance procedure. Reduce air pressure setting on gun and transfer pumps. Ensure the air supply is clean and dry. Apply powder in controlled area with a humidity of 50% ± 10%. |
| Powder is blowing around and out of the hopper | Air pressure too high, powder level too high, powder too fine (mix of virgin & reclaim powder), powder too fine (only virgin powder) or blocked hopper or poor venting | Check the IFS fluidizing section. Clean and check pick up tubes, pumps and hoses - replace if necessary; check sieve screen for proper operation and tears - fix/replace if necessary; ensure no foreign objects/materials in powder supply. Replace squashed hoses; remove kinks and replace if necessary. Replace worn parts, implement proper maintenance procedure. Check air supply for blockages; check and adjust the air settings to pumps. |
| No air percolating through the surface of the powder | Insufficient air pressure, plugged membrane, blocked membrane, powder too fine or powder has become compacted | Ensure humidity is controlled to required specification for your system & ensure that all the application and recovery equipment has a good ground. |
| Large air holes being blown through the surface of the powder | Powder level is too low, packed or moist powder, or damaged or plugged membrane | Check and ensure constant air supply. Remove kinks from hoses. Ensure tubes, hoses and guns properly cleaned; ensure air supply if free of oil or moisture. Ensure proper humidity levels in the application area. |
| Fine and coarse powder particles separating into different layers | Powder level too high, powder too fine (mix of virgin & reclaim powder) or powder to fine (only virgin powder) | Reduce the air pressure into the fluidizing bed. Remove excess powder from the hopper – the hopper should be 2/3 full when fluidized. Adjust the mix of virgin to reclaim powder. Contact IFS Coatings. Clean the hopper and vent and if necessary increase the vent size. |
| Poor charging, low film build, insufficient wrap | Inadequate kV settings, poor grounding, too much powder delivery, too much/little humidity in application room, powder too fine (virgin/reclaim mix) or powder too fine (virgin powder) | Check the air supply; increase the amount of air; check the airline to be sure it is supplying a suitable volume of air. Check the fluidizing membrane and if damaged or contaminated with oil or water replace with new membrane. Check the bottom of the fluidizing bed and clear of blockages. Adjust the mix of virgin to reclaim powder (mix of virgin & reclaim powder should be 50% to 50%). Loosen the compacted powder with a clean wooden stirring device and fluidize the powder with clean dry air (care must be taken not to damage the fluidizing membrane at the bottom of the hopper with the stirring device). |
| Poor penetration (powder not penetrating into faraday cage areas e.g. corners and recesses) | Poor voltage (too high or too low, powder/air velocity too high, poor grounding, inadequate application technique and/or poor automatic gun placement, poor spray pattern, powder too fine (virgin/reclaim mix), powder too fine (virgin), too little powder delivery | Add more powder – the hopper should be 2/3 full when fluidized. Unplug by manually loosening and fluidizing powder by stirring with clean dry instrument or clean, dry air; Ensure the compressed air and application room are free of moisture or high humidity. Check the membrane for plugged pores, cracks or holes and replace as necessary. |
| Back ionization/kV rejection – powder rebounds from the part | KV settings – voltage too high, spray distance too close, poor grounding, humidity levels too low, powder too fine (virgin/reclaim mix), powder too fine (virgin), or excess film thickness | Remove powder until the hopper is around 2/3 full when fluidized. Adjust the mix of virgin to reclaim powder. Contact Polychem Powder Coatings. |
| Guns spitting, surging and inconsistent powder feed | Not enough air pressure or volume, hoses kinked, crushed or too long, hoses, pumps, pick up tubes or guns with impact fusion, powder too fine (virgin/reclaim mix), powder too fine (virgin), powder not properly fluidizing | Check voltage at electrode, cable and power supply; Replace missing or broken electrodes; Clean and remove build up from electrodes. Check ground from conveyor through hanger to part (maximum ground is less than 1 Megohm at 500 volts); Clean and remove build-up of insulating materials (including powder) from conveyor, load bars and hangar. Reduce air pressure to allow the powder to charge properly and maintain a good gun to part distance. Too much humidity can reduce the charge on powder particles. Ensure humidity is controlled to the proper specification for your system. Maintain a proper virgin/reclaim mix. Contact Polychem powder coatings. |
| Poor spray pattern | Gun parts worn beyond equipment suppliers recommendations, blockage caused by impact fusion, hoses, pumps, pick up tubes or guns clogged by impact fusion, not enough powder feed or atomizing pressure | Adjust voltage and Micro Amps so powder can build evenly especially at edges and corners. Control air pressure to prevent powder from being blow out of recessed areas. Ensure adequate grounding (1 Megohm or less resistance to ground at 500 volts). Ensure that gun to part and gun to gun distances are suitably for proper powder charging. Use different nozzle or deflector (check with equipment manufacturer). Adjust virgin/reclaim mix. Contact Polychem. Increase rate of powder flow if needed. |
| Poor powder thickness or coverage | Electrostatic equipment not providing high enough kV, poor grounding, excessive powder delivery, excessive air velocity of powder feed settings causing the powder to be blown past the part, powder attracted to adjacent parts, too much moisture in the powder application area causing a disruption of the electrostatic charge to the powder particles | Reduce kVs (voltage) and check for adequate ground. Recommended spray distance is approximately 8-12 inches away from your product, depending on your equipment settings and part configuration. Confirm all your equipment is properly grounded. Control/adjust humidity to proper specification. Adjust virgin/reclaim mix. Contact Polychem. Reduce film thickness by decreasing spray time and/or powder flow air pressure. |
| Powder Sagging | Incoming part temperature too hot, or excess film thickness | Check equipment specifications and ensure air supply lines are correct size; Increase feed and/or atomizing air pressure. Replace worn hoses; ensure no sharp bends or excess hose runs; use the shortest hose runs possible and/or practical for manual and automatic guns. Check and clean hoses, pumps, pick up tubes and guns; Ensure compressed air supply is clean and dry; Ensure humidity is set at correct specification for your system. Adjust virgin/reclaim mix. Contact Polychem. |
| Foaming of the surface | IR-oven: temperature too high | Check and replace worn out nozzles, deflectors and electrode sleeves. Clean and remove any impact fusion from parts; Implement standard maintenance procedure. Check and clean hoses, pumps, pick up tubes and guns every day or on every shift. Ensure the compressed air supply is clean and dry; Ensure humidity is at correct specification for your system. Adjust the feed and atomizing air pressure to the application equipment for a consistent spray pattern. |
| Craters/fisheyes, pull away, voids | Oil or moisture in air lines, contamination with incompatible materials, contamination with incompatible powder, or poor cleaning or pretreatment | Increase line speed, or reduce the temperature. |
| Gloss difference | Over/under cured, contamination with incompatible powder, outgassing or micro pinholing | Inspect airlines and ensure air is clean and dry; check filters and drain or install traps; check oil absorption unit for excessive signs of oil. Make sure the gun, hopper and spray booth is completely cleaned and that the powder was stored correctly; check for and eliminate incompatible materials throughout the process e.g. silicones and lubricants. Clean guns, hoses and hoppers thoroughly after each color change to eliminate cross contamination of different coatings; ensure parts are completely dry before entering spray booth; use virgin powder. Check pretreatment equipment and concentrations; consult pretreatment supplier. |
| Poor color | Over/under cure, inadequate oven exhaust, poor natural gas quality | Run oven profile to determine if recommended time at temperature is achieved; increase/ decrease oven temperature or increase/decrease line speed or dwell time. Clean guns, hoses and hoppers; clean hangars; ensure parts are completely dry before entering spray booth; use virgin powder. Check and eliminate moisture in compressed air or powder; check substrate for porosity; film thickness too high. |
| Poor opacity | Film thickness too low | Run oven profile to determine if recommended time at temperature is achieved; increase/ decrease oven temperature or increase/decrease line speed or dwell time. Check for obstruction in exhaust stacks; ensure proper fan operation. Check with gas supplier for the amount of sulfur in the natural gas supply. |
| Contamination: other colors in cured film | Poor clean up between color changes or powder types | Increase film thickness – use higher voltage, longer spray time or denser powder cloud. |
| Inconsistent film thickness | Inadequate application pattern, booth air flow unbalance causing uneven spray pattern, inconsistent powder flow | Check application procedures. Consult your equipment supplier. Check for surging, spitting or interrupted powder flow. |
| Powder drifting through spray booth (inadequate air flow through booth) | Blinding of filter cartridges or final filters blocked | Clean or replace filters; check pulse air. Check for and eliminate moisture/oil in air supply. |
| Lumps or packed powder | Improper storage – temperature or humidity too high, or shelf life expired | Screen and sieve powder prior to spraying; consult Polychem |