If the rinsing water does not form a uniform wetting film on aluminum, this usually indicates an insufficient degreasing effect during pretreatment.

• Cause:
  Insufficient degreasing effect caused by poorly soluble oils, greases, high-temperature release agents or cured release agents.
  • Recommended solution:
    Increase the degreasing temperature, increase the chemical concentration, extend the treatment time and increase the spray pressure.
• Cause:
  Reduced effectiveness of the pretreatment chemicals caused by newly used release agents.
  • Recommended solution:
    Discuss the issue with the material supplier and pretreatment chemical supplier to identify a suitable solution.

Discoloration, cloudy appearance or milky stains on aluminum surfaces often occur directly after the etching process.

• Cause:
  Milky oxidation products remain on the surface due to insufficient etching action.
  • Recommended solution:
    Increase the etching temperature, increase the chemical concentration and increase the spray pressure.
• Cause:
  Dark and insoluble etching sludge remains on the workpiece surface.
  • Recommended solution:
    Increase rinsing times, check the conductivity of the rinsing water and extend the pickling time.
• Cause:
  Insoluble alloy components from the aluminum remain in the etching bath and affect the surface appearance.
  • Recommended solution:
    Use a milder etching process by reducing concentration, treatment time and temperature.

Stains or drying marks in the conversion layer are usually caused by residues from the pretreatment process remaining on the workpiece surface.

• Cause:
  Dried pretreatment residues remain on the surface after rinsing.
  • Recommended solution:
    Increase the rinsing time and regularly check the conductivity of the rinsing water.

If the rinsing water does not form a uniform wetting film on steel or galvanized steel, this usually indicates an insufficient degreasing effect during pretreatment.

• Cause:
  Insufficient degreasing effect caused by poorly soluble oils, greases, high-temperature release agents or cured release agents.
  • Recommended solution:
    Increase the degreasing temperature, increase the chemical concentration, extend the treatment time and increase the spray pressure.
• Cause:
  Reduced effectiveness of the pretreatment chemicals caused by newly used release agents.
  • Recommended solution:
    Discuss the issue with the material supplier and pretreatment chemical supplier to identify a suitable solution.

If the phosphate layer is not properly sealed or corrosion appears after coating, the phosphating process or rinsing quality is usually insufficient.

• Cause:
  The chemical bath composition is outside the specified operating range.
  • Recommended solution:
    Check the bath values regularly and prepare a new bath if necessary.
• Cause:
  Incorrect process parameters such as temperature, treatment time or concentration reduce the effectiveness of the phosphating process.
  • Recommended solution:
    Check all process parameters and follow the recommendations of the pretreatment manufacturer.
• Cause:
  Heavily contaminated rinsing baths cause carryover of chemicals onto the workpiece surface.
  • Recommended solution:
    Check the conductivity and dripping behavior of the rinsing water and replace contaminated rinsing baths if necessary.
• Cause:
  Insufficient rinsing leaves chemical residues on the workpiece surface.
  • Recommended solution:
    Increase rinsing times and regularly inspect and clean the spray nozzles.

A phosphate layer that becomes too thick or dusty is usually caused by excessive treatment times during the phosphating process.

• Cause:
  The workpieces remain in the phosphating stage for too long, resulting in excessive layer growth.
  • Recommended solution:
    Follow the treatment times recommended by the pretreatment manufacturer and avoid unnecessary process interruptions.

An uneven or spotty phosphate layer is usually caused by insufficient cleaning, uneven pretreatment or drying of chemicals on the workpiece surface.

• Cause:
  The surface is not sufficiently degreased before phosphating.
  • Recommended solution:
    Increase the degreasing time and temperature, increase the chemical concentration and check whether new release agents are present on the workpieces.
• Cause:
  The etching effect is insufficient, resulting in an uneven surface condition before phosphating.
  • Recommended solution:
    Increase etching time, temperature and concentration or mechanically pretreat the surface by blasting beforehand.
• Cause:
  Pretreatment chemicals dry on the surface between process stages.
  • Recommended solution:
    Prevent chemicals from drying on the workpieces between the different treatment zones.
• Cause:
  Uneven spraying caused by clogged or defective spray nozzles results in an irregular phosphate layer.
  • Recommended solution:
    Check all spray nozzles regularly for clogging, wear or defects.

Bimetallic or galvanic corrosion occurs when different metals come into contact with each other in the presence of moisture or other conductive media.

• Cause:
  Electrochemical reactions occur between different metals, leading to accelerated corrosion.
  • Recommended solution:
    Never use blasting media containing iron or steel on aluminum or stainless steel. Do not use the same abrasive materials for both steel and aluminum, and avoid unsuitable material combinations such as steel rivets on aluminum or aluminum rivets on steel.

Grinding traces or sanding marks become visible when the mechanical pretreatment of the surface is too coarse or uneven before coating.

• Cause:
  The preliminary sanding or grinding process was carried out with abrasives that are too coarse.
  • Recommended solution:
    Use suitable abrasive papers or particle sizes and avoid skipping more than one grit size between sanding steps.
• Cause:
  The blasting pressure is too high or the abrasive media are too aggressive for the substrate.
  • Recommended solution:
    Reduce the blasting pressure and select a more suitable abrasive material for the workpiece surface.

Holes or air channels in the fluidized powder surface indicate uneven fluidization of the powder. This can negatively affect powder transport and coating quality.

• Cause:
  The fluidizing air volume is too low, preventing the powder from remaining evenly suspended.
  • Recommended solution:
    Increase the fluidizing air volume until the powder surface moves evenly without visible holes or air channels.
• Cause:
  The fluidizing bed is clogged, contaminated or damaged and no longer distributes the air evenly.
  • Recommended solution:
    Inspect the fluidizing bed regularly and clean or replace it if necessary.
• Cause:
  Water or oil in the compressed air causes the powder to clump and fluidize poorly.
  • Recommended solution:
    Check the compressed air quality and use suitable oil and water separators.
• Cause:
  Excessive temperatures negatively affect the flow properties of the powder.
  • Recommended solution:
    Cool the coating room or compressed air supply to maintain stable fluidization.
• Cause:
  An excessive fine fraction from reclaimed powder changes the fluidization behavior.
  • Recommended solution:
    Increase the proportion of fresh powder to improve fluidization stability.

Blisters in the fluid container or powder leaking from the container indicate excessive fluidization. This causes unstable powder movement and uneven powder feeding.

• Cause:
  The fluidizing air volume is set too high, causing air bubbles or powder fountains inside the container.
  • Recommended solution:
    Reduce the fluidizing air volume until the powder surface moves gently and evenly without blistering or powder escaping from the container.

Powder deposits inside the powder hose occur when the powder is not conveyed evenly through the hose. The accumulated powder can suddenly detach and cause visible surface defects or uneven coating thicknesses.

• Cause:
  A worn collector nozzle affects the powder flow and promotes deposits inside the hose.
  • Recommended solution:
    Inspect the collector nozzle regularly and replace worn components if necessary.
• Cause:
  The proportion of dosing air is too low, resulting in unstable powder transport.
  • Recommended solution:
    Reduce the powder quantity and increase the total air volume to improve powder transport.
• Cause:
  Unsuitable hose routing with tight bends or kinks restricts powder flow.
  • Recommended solution:
    Avoid tight bend radii and ensure smooth hose routing without kinks.
• Cause:
  The powder hose is constricted by cable ties or external pressure.
  • Recommended solution:
    Inspect the hose regularly for constrictions and remove anything that restricts powder flow.
• Cause:
  The powder hose is too long, causing unstable powder transport and deposits.
  • Recommended solution:
    Shorten the hose length or increase the total air volume to maintain stable powder transport.

If powder falls off before curing, the powder does not adhere sufficiently to the workpiece surface after spraying. This is usually caused by poor grounding, insufficient charging or incorrect application settings.

• Cause:
  Inadequate grounding prevents the powder from adhering properly to the workpiece surface.
  • Recommended solution:
    Clean the hooks down to bare metal and measure the grounding resistance to ensure proper grounding.
• Cause:
  The electrostatic charge of the powder is too low.
  • Recommended solution:
    Check the actual voltage and current settings and increase them if necessary.
• Cause:
  The powder output is too high, preventing sufficient charging of the powder particles.
  • Recommended solution:
    Reduce the powder output to improve electrostatic charging and adhesion.
• Cause:
  Excessive total air or tribo air volume creates blow-off effects on the workpiece surface.
  • Recommended solution:
    Reduce the air settings to achieve a softer and more stable powder cloud.
• Cause:
  The gun distance is too short, causing blow-off effects and insufficient powder charging.
  • Recommended solution:
    Check the spraying distance and adjust the high-voltage settings accordingly.
• Cause:
  The coating thickness is too high, reducing powder adhesion before curing.
  • Recommended solution:
    Reduce the coating thickness and apply the powder more evenly.
• Cause:
  The conveyor system runs unevenly, causing vibrations that shake the powder off the surface.
  • Recommended solution:
    Inspect the conveyor system and eliminate irregular movements or vibrations.

If powder trickles or falls off inside edges, the powder becomes overcharged during coating. This usually occurs on vertical profiles and leads to cracking or powder movement before curing.

• Cause:
  The electrostatic charge is too high or ion-leakage rings are used incorrectly.
  • Recommended solution:
    Use a current limiter below 10 µA and remove ion-leakage rings if necessary.
• Cause:
  The air velocity is too high or the spraying distance is too short, creating blow-off effects.
  • Recommended solution:
    Adjust the air settings to create a softer powder cloud and increase the spraying distance.
• Cause:
  Inadequate grounding causes unstable powder adhesion on inside edges.
  • Recommended solution:
    Check the grounding and connect profiles both at the top and bottom using grounding clamps.

Lumps in the powder carton or fluid container are usually caused by unsuitable storage conditions, excessive pressure or high temperatures. These factors negatively affect the flow behavior and processability of the powder coating.

• Cause:
  The powder is stored at excessively high temperatures.
  • Recommended solution:
    Reduce the storage temperature and sieve the powder before use if necessary.
• Cause:
  The vibration plate is operated continuously, causing unnecessary compaction of the powder.
  • Recommended solution:
    Only activate the vibration plate when required and avoid continuous operation.
• Cause:
  The temperature of the fluidizing air is too high.
  • Recommended solution:
    Check the compressed air supply and reduce the air temperature if necessary.
• Cause:
  Excessive pressure at pumps or pinch valves compresses the powder.
  • Recommended solution:
    Check the pressure settings and install screens if required.
• Cause:
  Excessive pressure during storage causes the powder to compact.
  • Recommended solution:
    Avoid stacking powder cartons or sacks on top of each other.
• Cause:
  The powder coating has exceeded its recommended shelf life.
  • Recommended solution:
    Check the expiry date on the packaging and use fresh powder if necessary.

If inside edges or cavities are poorly coated, the powder cannot penetrate sufficiently into recessed areas. This is often caused by electrostatic effects, unsuitable air settings or unfavorable part geometry.

• Cause:
  Incorrect air settings create blow-off effects and prevent the powder from penetrating into cavities.
  • Recommended solution:
    Adjust the air settings to create a soft and stable powder cloud.
• Cause:
  The powder output is too high, resulting in poor penetration into recessed areas.
  • Recommended solution:
    Reduce the powder output to improve penetration behavior.
• Cause:
  Inadequate grounding reduces the electrostatic attraction of the powder in cavities and inside edges.
  • Recommended solution:
    Check the mounting and grounding of the workpieces regularly.
• Cause:
  The voltage is too high or the electric field is too strong, creating a Faraday cage effect.
  • Recommended solution:
    Reduce the voltage, lower the current limit and use ion-leakage rings if necessary.
• Cause:
  The spacing between the components is too small.
  • Recommended solution:
    Increase the spacing between the workpieces to improve powder penetration.
• Cause:
  The workpiece geometry is difficult or impossible to coat effectively.
  • Recommended solution:
    Adapt the component design or coating setup to improve accessibility of recessed areas.

If the coating thickness is too high, the cured surface may appear uneven, wavy or show defects such as orange peel or pinholes.

• Cause:
  The workpieces are too hot during coating, causing excessive powder adhesion.
  • Recommended solution:
    Allow the parts to cool down sufficiently before coating, ideally to around 40 °C.
• Cause:
  The powder output is set too high.
  • Recommended solution:
    Reduce the powder quantity and adjust the application settings accordingly.
• Cause:
  Unfavorable workpiece geometry or mounting positions allow powder to accumulate on horizontal surfaces.
  • Recommended solution:
    Adjust the mounting position of the workpieces to prevent excessive powder accumulation.
• Cause:
  The spraying distance between gun and workpiece is too short.
  • Recommended solution:
    Increase the spraying distance to achieve a more even coating thickness.

If the coating thickness is too low, the substrate may remain visible after curing and the surface can appear rough or grainy.

• Cause:
  Inadequate grounding reduces powder adhesion to the workpiece surface.
  • Recommended solution:
    Clean the hooks down to bare metal and regularly check the grounding resistance.
• Cause:
  The electrostatic charging of the powder is insufficient.
  • Recommended solution:
    Increase the voltage setting and current limit to improve powder charging.
• Cause:
  The powder output is too low or the powder feed is unstable.
  • Recommended solution:
    Increase the powder output and check the collector nozzles for wear or blockage.
• Cause:
  Suction pipes or injectors in the powder container are clogged.
  • Recommended solution:
    Inspect and clean the suction pipes and injectors regularly.
• Cause:
  The tribo charging effect is insufficient for the selected powder coating.
  • Recommended solution:
    Check whether the powder is suitable for tribo application and increase the tribo air if necessary.
• Cause:
  Defective application equipment such as guns, cables or control units affects the powder transfer efficiency.
  • Recommended solution:
    Inspect the coating equipment regularly and replace defective components.
• Cause:
  The spraying distance between gun and workpiece is too large.
  • Recommended solution:
    Reduce the spraying distance to improve powder deposition.
• Cause:
  The powder hose material is unsuitable for the application.
  • Recommended solution:
    Use a grounded powder hose to ensure stable powder transport and charging.

An uneven coating thickness can become visible visually or only through measurement. It is usually caused by inconsistent gun movement, unstable powder feeding or poor grounding.

• Cause:
  With short-stroke systems, the gun distance or stroke adjustment is inconsistent.
  • Recommended solution:
    Measure and adjust the gun distance and optimize the stroke settings. As a rule of thumb, the stroke should correspond to the gun distance up to approximately 50 mm.
• Cause:
  With long-stroke systems, the sine curve settings are incorrect.
  • Recommended solution:
    Adjust the stroke speed and stroke height according to the conveyor speed and workpiece geometry.
• Cause:
  The powder feed or powder output is irregular.
  • Recommended solution:
    Check fluidization, powder hoses and collector nozzles to ensure stable powder transport.
• Cause:
  Manual coating is applied unevenly.
  • Recommended solution:
    Train coating personnel to maintain consistent gun movement and coating technique.
• Cause:
  Inadequate grounding reduces consistent powder deposition on the workpiece.
  • Recommended solution:
    Clean the hooks down to bare metal and regularly check the grounding resistance.

Deposits on the spray nozzle occur when powder or effect additives accumulate on nozzle components during coating. These deposits can later detach and become visible as inclusions or raised defects on the cured surface.

• Cause:
  The nozzle slot is worn and no longer distributes the powder evenly.
  • Recommended solution:
    Inspect the nozzle slot regularly and replace worn components if necessary.
• Cause:
  The nozzle attachment is worn, resulting in unstable powder flow and increased deposits.
  • Recommended solution:
    Check the nozzle attachment regularly and replace damaged parts.
• Cause:
  The powder output is too high, causing excessive powder accumulation on the nozzle.
  • Recommended solution:
    Reduce the powder quantity to achieve a more stable and even powder cloud.
• Cause:
  With baffle plate nozzles, the purge air volume is insufficient.
  • Recommended solution:
    Adjust the purge air settings to keep the nozzle clean during operation.
• Cause:
  With effect powder coatings, the electrostatic charge is too high, causing effect pigments to accumulate on the nozzle.
  • Recommended solution:
    Remove ion-leakage rings if necessary to reduce the electrostatic charge.
• Cause:
  Unsuitable powder hose material promotes sintering and deposits when using effect powder coatings.
  • Recommended solution:
    Use grounded hose material to ensure stable powder transport and reduce deposits.

Spitting on the surface appears as local powder accumulations or inclusions that become visible after curing. These defects are usually caused by unstable powder transport or deposits within the coating system.

• Cause:
  Insufficient fluidization results in unstable powder transport.
  • Recommended solution:
    Check the fluidization settings and ensure the powder surface moves evenly without holes, blisters or powder fountains.
• Cause:
  Powder deposits inside the powder hose detach suddenly during coating.
  • Recommended solution:
    Inspect powder hoses, air settings and hose routing regularly to avoid powder deposits.
• Cause:
  When using effect powder coatings, unsuitable hose material can cause sintering inside the powder hose.
  • Recommended solution:
    Use grounded hose material to ensure stable powder transport and reduce deposits.
• Cause:
  Sintered deposits on the spray nozzle detach during coating and become visible on the cured surface.
  • Recommended solution:
    Clean and inspect spray nozzles regularly and replace worn nozzle components when necessary.
• Cause:
  Uneven powder feeding causes fluctuations in powder output and visible defects on the surface.
  • Recommended solution:
    Adjust the conveying and dosing air settings to ensure stable powder transport.
• Cause:
  Kinked or loose conveying and dosing air hoses create unstable powder transport conditions.
  • Recommended solution:
    Check all hoses and connections between the injector and control unit for damage or loose fittings.

Cratering appears as circular surface defects where the substrate becomes visible. These defects are usually caused by contamination, residues or outgassing during curing.

• Cause:
  Insufficient pretreatment or chemical residues on the workpiece surface prevent proper flow of the powder coating.
  • Recommended solution:
    Check the pretreatment parameters and coordinate the process with the pretreatment supplier if necessary.
• Cause:
  Silicones or moisture on the surface disturb the wetting behavior of the coating film.
  • Recommended solution:
    Clean and dry the surfaces thoroughly and check for dripping contamination from the conveyor system.
• Cause:
  Residues from sprays, creams or other auxiliary products affect the surface tension of the coating film.
  • Recommended solution:
    Check all products used around the coating line and replace unsuitable materials if necessary.
• Cause:
  A contaminated coating plant introduces impurities into the coating process.
  • Recommended solution:
    Clean the coating plant thoroughly and regularly.
• Cause:
  Carryover from other powder coatings causes surface disturbances and craters.
  • Recommended solution:
    Clean the booth, powder circuit and conveying system carefully during color changes.
• Cause:
  Outgassing from the substrate, coating materials or trapped gases causes bubbles in the coating film.
  • Recommended solution:
    Preheat the component before coating and ensure the correct curing parameters are used.
• Cause:
  Overcoating putties or wet coatings may release gases during curing.
  • Recommended solution:
    Check the suitability of the underlying coating system and temper the component if necessary.
• Cause:
  Oil contamination in the ambient air or compressed air affects the surface quality.
  • Recommended solution:
    Inspect and maintain the compressed air filters regularly.
• Cause:
  Solvent residues from cleaning the first coating layer have not fully evaporated before recoating.
  • Recommended solution:
    Temper the component after cleaning and allow all solvents to evaporate completely before coating.

Pinholes are very fine pores or holes in the coating surface that are usually caused by trapped gases or excessive outgassing during curing.

• Cause:
  The curing temperature or heating rate is too high, causing gases to escape too quickly through the coating film.
  • Recommended solution:
    Increase the heating-up time and reduce the curing temperature if necessary.
• Cause:
  The powder coating contains excessive moisture due to unsuitable storage conditions.
  • Recommended solution:
    Check the storage conditions and dry the powder if necessary before use.
• Cause:
  The powder coating is excessively charged, resulting in an unstable coating film.
  • Recommended solution:
    Reduce the coating thickness and voltage settings and use a current limiter if necessary.
• Cause:
  Air inclusions or outgassing from the substrate create pores during curing.
  • Recommended solution:
    Temper the workpieces before coating and optimize the curing conditions.
• Cause:
  Insufficient pretreatment or chemical residues remain on the workpiece surface.
  • Recommended solution:
    Check the pretreatment parameters and contact the pretreatment supplier if necessary.

A picture frame effect appears as visible differences in gloss, structure or surface appearance around the edges of the workpiece.

• Cause:
  The voltage or spray current is too high, causing excessive powder accumulation at the edges.
  • Recommended solution:
    Reduce the voltage and limit the spray current.
• Cause:
  Excessive wrap-around causes increased powder deposition along the workpiece edges.
  • Recommended solution:
    Adjust the high-voltage settings, gun distance and total air volume.
• Cause:
  Excessive coating thickness or incorrect gun overrun and underrun create visible edge effects.
  • Recommended solution:
    Adjust the application settings according to the workpiece geometry and hanger configuration.
• Cause:
  With fine-structure powder coatings, inconsistent powder separation affects the surface appearance at the edges.
  • Recommended solution:
    Use a current limiter and ion-leakage rings to stabilize the electrostatic charging behavior.

Impurities or inclusions on the cured surface are caused by foreign particles entering the coating process during application or reclaiming.

• Cause:
  Deposits released from the cyclone contaminate the powder coating.
  • Recommended solution:
    Inspect the cyclone for sintering deposits and clean it regularly to remove granules and contamination.
• Cause:
  Dirt particles are drawn into the booth during the reclaiming process.
  • Recommended solution:
    Ensure clean room air conditions and use suitable screens during reclaiming.
• Cause:
  Dust or contamination from the surrounding environment enters the coating process.
  • Recommended solution:
    Maintain a high level of cleanliness throughout the coating area.
• Cause:
  Residual powder from previous color changes remains in the powder circulation system.
  • Recommended solution:
    Clean the booth and powder circuit more thoroughly and follow the recommendations of the plant manufacturer.
• Cause:
  Fibers from cleaning cloths, workwear or other materials become embedded in the coating surface.
  • Recommended solution:
    Use suitable cleaning materials and lint-free work clothing whenever possible.

Blisters in the coating film are visible elevations or burst bubbles that form during curing. They are usually caused by moisture, contamination or outgassing from the substrate.

• Cause:
  Water or oil trapped beneath the coating film evaporates during curing and creates blisters.
  • Recommended solution:
    Thoroughly clean and dry the workpieces before coating.
• Cause:
  Outgassing from the substrate releases gases through the coating film during curing.
  • Recommended solution:
    Ensure proper galvanization and pretreatment, temper the workpieces before coating and use outgassing-friendly powder coatings if necessary.
• Cause:
  Overcoated putties or wet coatings release trapped solvents or gases during curing.
  • Recommended solution:
    Check the suitability of the underlying coating system and temper the component if required.
• Cause:
  Blasted parts were not properly degreased before blasting.
  • Recommended solution:
    Degrease the workpieces thoroughly before carrying out the blasting process.

Edge build-ups or droplet formations occur when excessive coating material accumulates at the edges of the workpiece during melting and curing.

• Cause:
  The coating thickness is too high, resulting in excessive powder accumulation at the edges.
  • Recommended solution:
    Reduce the coating thickness and apply the powder more evenly.
• Cause:
  The curing temperature or heating rate is too high, causing excessive flow of the coating film.
  • Recommended solution:
    Check and optimize the oven temperature settings.
• Cause:
  The workpiece temperature is too high before coating.
  • Recommended solution:
    Allow the workpieces to cool sufficiently before coating.
• Cause:
  The workpiece edges are too sharp, encouraging coating material to accumulate during curing.
  • Recommended solution:
    Deburr or round off sharp edges before coating whenever possible.

Wetting impairments occur when the powder coating does not adhere or flow evenly on the substrate during melting and curing.

• Cause:
  Insufficient pretreatment reduces the adhesion and wetting behavior of the powder coating.
  • Recommended solution:
    Check the pretreatment and rinsing parameters regularly and avoid process interruptions.
• Cause:
  Oil or grease is carried over into the pretreatment process and contaminates the workpiece surface.
  • Recommended solution:
    Ensure that all pretreatment baths remain clean and properly maintained.
• Cause:
  The workpiece surface is contaminated after pretreatment.
  • Recommended solution:
    Only handle pretreated workpieces with clean gloves and avoid contamination before coating.
• Cause:
  The retention time in the oven is significantly too long, affecting the coating behavior during curing.
  • Recommended solution:
    Follow the recommended curing parameters and avoid excessive curing times.

An irregular fine structure appears when the surface texture is uneven, cloudy or streaky instead of fine and uniform. This is usually caused by unstable coating conditions or excessive electrostatic charging.

• Cause:
  The coating thickness is too high, affecting the development of the fine structure.
  • Recommended solution:
    Reduce the coating thickness and apply the powder more evenly.
• Cause:
  The electrostatic charge is too high, causing uneven structure formation.
  • Recommended solution:
    Reduce the voltage, lower the current limit and use ion-leakage rings if necessary.
• Cause:
  The powder output is uneven due to unstable powder transport or fluidization.
  • Recommended solution:
    Check the fluidization settings and air values to ensure stable powder feeding.
• Cause:
  The spraying distance is too short, resulting in visible streaks on the surface.
  • Recommended solution:
    Increase the spraying distance to achieve a more uniform surface structure.

Color deviations with solid colors are usually caused by differences in coating thickness, curing conditions or contamination during the coating process.

• Cause:
  The coating thickness is too low and the substrate remains partially visible.
  • Recommended solution:
    Increase the coating thickness to achieve complete coverage of the substrate.
• Cause:
  The surface has been over-cured, affecting the final color shade.
  • Recommended solution:
    Follow the correct curing conditions and perform oven measurements regularly.
• Cause:
  Different curing conditions lead to visible color differences between workpieces.
  • Recommended solution:
    Ensure consistent curing conditions for all coated parts.
• Cause:
  Materials with different thicknesses are cured together, resulting in different object temperatures.
  • Recommended solution:
    Check hanger configuration and oven settings to ensure uniform curing conditions.
• Cause:
  The workpieces were pretreated incorrectly and stains remain visible through the coating.
  • Recommended solution:
    Check the pretreatment process and eliminate visible substrate defects before coating.
• Cause:
  Metamerism causes the perceived color to change under different light sources.
  • Recommended solution:
    Assess colors under indirect daylight or standardized daylight lamps such as D65 lighting.
• Cause:
  Fluctuating gloss levels make the surface appear visually darker or lighter.
  • Recommended solution:
    Check the coating and curing conditions to maintain a consistent gloss level.
• Cause:
  A directly heated gas oven causes yellowing of the coating surface.
  • Recommended solution:
    Use an indirectly heated oven to avoid yellowing effects.
• Cause:
  Different substrate base colors remain visible during recoating applications.
  • Recommended solution:
    Ensure a uniform substrate color or remove the old coating before recoating.
• Cause:
  Contamination from other powder coatings affects the final color appearance.
  • Recommended solution:
    Clean the coating system thoroughly and use fresh powder if necessary.

Color deviations with effect powder coatings are usually caused by variations in application parameters, coating thickness or the distribution of metallic and effect pigments within the coating film.

• Cause:
  Batch variations between different powder batches result in visible color differences.
  • Recommended solution:
    Use powder from the same batch for the entire coating job and for all reference samples.
• Cause:
  Different application parameters influence the orientation of the effect pigments.
  • Recommended solution:
    Document all coating settings and use identical parameters for repeat jobs.
• Cause:
  The proportion of reclaimed powder is too high or inconsistent.
  • Recommended solution:
    Increase the proportion of fresh powder or coat without reclaiming if necessary.
• Cause:
  Different coating systems, plants or operators create varying effect appearances.
  • Recommended solution:
    Use the same coating system and application setup for all workpieces within the same project.
• Cause:
  Inadequate grounding affects the electrostatic orientation of the effect pigments.
  • Recommended solution:
    Clean the hooks down to bare metal and regularly check the grounding resistance.
• Cause:
  The spraying distance is incorrect, resulting in an uneven effect appearance.
  • Recommended solution:
    Follow the recommended spraying distances specified in the processing guidelines.

Color deviations compared to the master sample or color chart are usually caused by differences in coating thickness, curing conditions, application parameters or lighting conditions.

• Cause:
  Differences between powder batches result in visible shade deviations.
  • Recommended solution:
    Use powder from the same batch for the entire coating job and for all comparison samples.
• Cause:
  Different application parameters influence the orientation and appearance of the effect pigments.
  • Recommended solution:
    Document all coating settings and use identical parameters for repeat applications.
• Cause:
  The reclaimed powder content is too high or inconsistent.
  • Recommended solution:
    Increase the proportion of fresh powder or avoid reclaiming for critical color applications.
• Cause:
  Different coating plants or operators create variations in the surface appearance.
  • Recommended solution:
    Use the same coating system, application setup and operator whenever possible.
• Cause:
  Inadequate grounding affects the powder deposition and pigment orientation.
  • Recommended solution:
    Clean the hooks down to bare metal and regularly check the grounding resistance.
• Cause:
  The spraying distance is incorrect, affecting the visual appearance of the coating.
  • Recommended solution:
    Follow the spraying distance recommendations defined in the processing guidelines.

Effect fluctuations with effect powder coatings occur when the orientation or distribution of the effect pigments changes during application. This can lead to visible differences between workpieces or even within the same component surface.

• Cause:
  The high-voltage or electrostatic charging settings have been changed.
  • Recommended solution:
    Use identical application settings throughout the entire coating process and coat consistently either with or without ion-leakage rings.
• Cause:
  The fresh powder dosage is inconsistent, resulting in varying powder composition.
  • Recommended solution:
    Use automated dosing for fresh and reclaimed powder whenever possible.
• Cause:
  Coating starts with fresh powder only, while reclaimed powder is added later during production.
  • Recommended solution:
    Before starting production, feed a small amount of powder through the reclaiming system and mix it with the fresh powder.
• Cause:
  Manual coating is applied unevenly.
  • Recommended solution:
    Train coating personnel accordingly and use manual pre-coating where required.
• Cause:
  The spraying distance is too short or the powder output is too high, especially on profile sections.
  • Recommended solution:
    Increase the spraying distance and reduce the powder quantity.
• Cause:
  The powder feed is unstable due to poor fluidization or deposits in the powder hose.
  • Recommended solution:
    Check fluidization, powder hoses and air settings to maintain a soft and stable powder cloud.
• Cause:
  The powder is fed directly from the supply carton instead of a fluid container.
  • Recommended solution:
    Use a fluid container to ensure stable and homogeneous powder feeding.
• Cause:
  Separation of powder and effect additives occurs during transport or application.
  • Recommended solution:
    Reduce the high-voltage setting and lower the total air volume.
• Cause:
  Deposited or sintered powder accumulates on the electrode.
  • Recommended solution:
    Check and adjust the purging air settings regularly.

Streaks or clouding with effect powder coatings are caused by uneven powder deposition or irregular orientation of the effect pigments during application.

• Cause:
  The spraying distance is too short, resulting in uneven effect distribution.
  • Recommended solution:
    Increase the spraying distance to achieve a more uniform effect appearance.
• Cause:
  The powder output is too high, causing irregular coating thickness and visible clouding.
  • Recommended solution:
    Reduce the powder output and ensure a soft and even powder cloud.
• Cause:
  Manual follow-up coating is applied unevenly.
  • Recommended solution:
    Train coating personnel accordingly and use controlled manual pre-coating where required.
• Cause:
  The total air volume is too high, causing unstable powder application.
  • Recommended solution:
    Increase the spraying distance and optimize the air settings to maintain a soft powder cloud.
• Cause:
  Inadequate grounding affects the electrostatic deposition of the powder.
  • Recommended solution:
    Clean the hooks down to bare metal and regularly check the grounding resistance.
• Cause:
  With long-stroke systems, incorrect sine-curve settings create uneven coating patterns.
  • Recommended solution:
    Adjust the stroke height, stroke speed and conveyor speed according to the gun distance and workpiece geometry.
• Cause:
  The spray gun is defective and no longer applies the powder evenly.
  • Recommended solution:
    Inspect the coating equipment and measure the gun voltage regularly.
• Cause:
  The powder is fed directly from the supply carton instead of a fluid container.
  • Recommended solution:
    Use a fluid container to ensure stable powder feeding.
• Cause:
  The purging air or gun air settings are too high.
  • Recommended solution:
    Reduce the purging air and gun air settings to stabilize the powder cloud.

Insufficient opacity occurs when the substrate remains visible after coating. This is usually caused by low coating thickness, unsuitable application settings or visible substrate structures.

• Cause:
  The coating thickness is too low to fully cover the substrate.
  • Recommended solution:
    Increase the coating thickness and ensure the minimum recommended coating thickness is achieved.
• Cause:
  With long-stroke systems, incorrect sine-curve settings create uneven powder distribution.
  • Recommended solution:
    Adjust the stroke height, stroke speed and conveyor speed according to the gun distance and workpiece geometry.
• Cause:
  With short-stroke systems, the gun distance or stroke adjustment is inconsistent.
  • Recommended solution:
    Measure and adjust the gun distance and optimize the stroke settings accordingly.
• Cause:
  The natural color of the substrate, such as brass, steel or aluminum, remains visible through the coating.
  • Recommended solution:
    Increase the coating thickness to improve coverage.
• Cause:
  The substrate surface structure from sanding or blasting remains visible after coating.
  • Recommended solution:
    Reduce the surface roughness and prepare the substrate more evenly before coating.

Fluctuating gloss levels are usually caused by inconsistent curing conditions, coating thickness variations or changes in powder quality.

• Cause:
  The curing conditions are incorrect and the powder coating is over-cured or under-cured.
  • Recommended solution:
    Check the curing window regularly and perform oven measurements to verify the actual object temperature.
• Cause:
  Materials with very different thicknesses are cured together in the oven.
  • Recommended solution:
    Adjust the hanger configuration and verify the curing conditions by oven measurement.
• Cause:
  The powder has been stored for too long or at excessively high temperatures.
  • Recommended solution:
    Improve the storage conditions and use fresh powder if necessary.
• Cause:
  The proportion of reclaimed powder is too high.
  • Recommended solution:
    Increase the proportion of fresh powder to stabilize the surface appearance.
• Cause:
  The voltage is too low or the powder charge is insufficient.
  • Recommended solution:
    Increase the voltage and adjust the current limiter to a higher value.
• Cause:
  The coating thickness is excessive or uneven.
  • Recommended solution:
    Reduce the coating thickness and ensure a more uniform powder application.

If the surface cracks or chips, the required mechanical properties of the coating film have not been achieved. This is usually caused by incorrect curing conditions, unsuitable multilayer systems or insufficient pretreatment.

• Cause:
  The oven settings are incorrect and the coating is over-cured or under-cured.
  • Recommended solution:
    Check the curing window regularly and perform oven measurements to verify the actual object temperature.
• Cause:
  In multilayer coating systems, the coating process is not carried out correctly.
  • Recommended solution:
    Follow the applicable processing guidelines for multilayer coating systems.
• Cause:
  The pretreatment is insufficient, reducing adhesion and flexibility of the coating film.
  • Recommended solution:
    Check the pretreatment parameters regularly and optimize the cleaning and pretreatment process.

If the coating layer flakes or peels off, the adhesion between the coating film and the substrate is insufficient. This is usually caused by incorrect curing conditions, contamination or unsuitable pretreatment.

• Cause:
  The oven settings are incorrect and the coating is over-cured or under-cured.
  • Recommended solution:
    Check the curing window regularly and perform oven measurements to verify the actual object temperature.
• Cause:
  In multilayer coating systems, the coating process is not carried out correctly.
  • Recommended solution:
    Follow the applicable processing guidelines for multilayer coating systems.
• Cause:
  No suitable primer has been applied before coating.
  • Recommended solution:
    Follow the specifications in the technical data sheet and use the recommended primer system.
• Cause:
  Oils, grease or release agents remain on the surface before coating.
  • Recommended solution:
    Thoroughly clean and pretreat the surface before coating.
• Cause:
  Rust or dust remains on the substrate surface.
  • Recommended solution:
    Clean and pretreat the workpieces thoroughly before coating.
• Cause:
  Laser-cut edges were not properly pretreated before coating.
  • Recommended solution:
    Mechanically process the laser-cut edges by grinding or blasting before coating.
• Cause:
  Aluminum parts were insufficiently pretreated, for example due to poor degreasing or inadequate pickling removal.
  • Recommended solution:
    Increase the pickling removal rate above 1.5 g/m² and improve the degreasing process.
• Cause:
  The primer layer was fully cured before overcoating, reducing intercoat adhesion.
  • Recommended solution:
    Allow the primer to gel only and follow the applicable processing guidelines.
• Cause:
  A directly heated gas oven affects the intercoat adhesion.
  • Recommended solution:
    Use an indirectly heated gas or electric oven.
• Cause:
  The storage time before overcoating is too long.
  • Recommended solution:
    Carry out the overcoating process within 24 hours whenever possible.

If the conductive properties are outside the required range, the surface resistance of the coating does not meet the specified values. This is usually caused by unsuitable coating thickness, incorrect measurement methods or the wrong powder coating type.

• Cause:
  The coating thickness is too low or too high, affecting the surface resistance of the coating.
  • Recommended solution:
    Adjust the coating thickness according to the specifications and check it regularly during production.
• Cause:
  The measurement method is incorrect or does not comply with the required standard.
  • Recommended solution:
    Perform the measurement according to DIN EN 61340-2-3 using the correct electrode setup and spacing.
• Cause:
  An unsuitable powder coating has been selected for conductive applications.
  • Recommended solution:
    Use a conductive powder coating specifically designed for electrostatic discharge applications.

If the surface does not flow smoothly, the cured coating appears wavy or uneven. This is usually caused by incompatibilities, excessive coating thickness or insufficient pretreatment.

• Cause:
  The powder coating is incompatible with other powders remaining in the coating system.
  • Recommended solution:
    Clean the coating plant thoroughly and use fresh powder if necessary.
• Cause:
  The coating thickness is too high, negatively affecting the flow behavior during curing.
  • Recommended solution:
    Reduce the coating thickness and apply the powder more evenly.
• Cause:
  The pretreatment process is insufficient and affects the surface quality of the coating.
  • Recommended solution:
    Adjust the pretreatment parameters and coordinate the process with the pretreatment supplier if necessary.