| GUN & EQUIPMENT PROBLEMS |
| No powder coming out of gun | - Clogged nozzle or tip: Powder buildup, moisture-clumped powder, or debris blocking the nozzle. Remove the tip and clean thoroughly with compressed air. Inspect the electrode for powder caking around the tip.
- Air supply issue: Compressor not running, air line kinked or disconnected, regulator closed. Verify air is flowing to the gun — you should feel air at the tip even without powder loaded.
- Powder cup empty or not seated: Check that the cup has powder and is properly threaded onto the gun. On suction-feed guns, a loose cup breaks the venturi seal.
- Blocked powder path: Powder can pack and solidify inside the gun body, hose, or pickup tube — especially if moisture got into the system. Disassemble the powder path and blow out all components with dry compressed air.
- Moisture in air lines: Water in compressed air causes powder to clump and block the system. Install a water separator/filter on your air line before the gun. Drain your compressor tank regularly.
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| Pulsing, surging, or sputtering powder flow | - Worn nozzle: Over time the nozzle opening wears unevenly, creating inconsistent flow. Replace the nozzle — they are wear items.
- Kinked or pinched powder hose: On guns with external hoses, a kink restricts flow and causes pulsing. Straighten the hose or consider a larger-diameter replacement.
- Moisture in powder: Damp powder clumps and feeds unevenly. Discard damp powder. Store powder sealed in a cool, dry location below 77°F.
- Fluctuating air pressure: Compressor cycling, leaks in air lines, or an undersized compressor cause pressure drops. Use a regulator with a gauge at the gun to verify stable pressure. Most guns operate best at 5–15 PSI.
- Powder buildup inside gun: Residual powder from previous colors or moisture-caked powder inside the gun body. Disassemble and clean all internal passages.
- Pickup tube partially blocked: On cup-fed guns, the pickup tube (the tube inside the cup) can partially clog. Remove and blow out.
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| Uneven or lopsided spray pattern | - Worn or damaged deflector/diffuser tip: The deflector disk or cone that shapes the spray pattern wears over time. Replace with a new deflector — even small chips cause uneven patterns.
- Partially clogged nozzle: Powder buildup on one side of the nozzle opening causes the spray to skew. Clean or replace the nozzle.
- Wrong tip for the application: Round tips produce a cone pattern; flat tips produce a fan. Use the tip that matches your part geometry.
- Bent or damaged electrode: If the center electrode is bent, the electrostatic field is uneven. Inspect and straighten or replace the electrode.
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| Gun not charging powder (powder falls off part) | - Grounding problem — #1 cause: Verify twin grounding setup (see grounding reference box above). Both connections — controller-to-rod and rod-to-part — must be intact and making contact with bare metal. A ground clamp on painted, powdered, or rusty metal is not a ground.
- Damaged or worn electrode: The charging electrode (needle) generates the electrostatic field. If it’s cracked, heavily worn, or caked with powder, it won’t charge properly. Remove, inspect, and replace if needed.
- Electrode housing cracked: The insulating sleeve around the electrode can crack, allowing the charge to short to the gun body instead of the powder. Inspect and replace if damaged.
- kV set too low: If the voltage is set very low, the charge may be insufficient to hold powder on the part — especially on second coats or parts further from the gun. Increase kV.
- Power supply or controller failure: If the controller isn’t powering the high-voltage cascade, no charge is generated. Check that the controller is on, the cable between gun and controller is fully connected, and any indicator lights are functioning.
- Excessive humidity: Very high humidity (above 60–65% RH) reduces electrostatic charging efficiency. Dehumidify your coating area if possible, or increase kV to compensate.
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| Gun sparking or arcing | - Gun too close to part: Holding the gun too close (under 4 inches) to a grounded part can cause visible arcing from the electrode to the part. Maintain 6–10 inches distance.
- kV set too high for the distance: At very high kV settings and close distance, the electrostatic field can exceed the air gap’s breakdown voltage. Reduce kV or increase distance.
- Damaged electrode insulation: Cracked insulator allows current to path where it shouldn’t. Inspect and replace.
- Powder buildup near electrode: Packed powder around the electrode tip can create a conductive path. Clean the tip and electrode housing thoroughly.
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| Powder clumping in cup or hopper | - Moisture absorption: Powder left exposed to humid air absorbs moisture and clumps. Always keep powder sealed when not in use. Discard powder that has been open in high humidity for extended periods.
- Old or expired powder: Powder degrades over time, especially in poor storage conditions. Shelf life is typically 1 to 2 years in proper storage. If it clumps when pinched between your fingers, it’s compromised.
- Temperature exposure: Powder stored above 77°F or exposed to temperature swings can partially fuse and clump. Store in a cool, stable environment.
- Sieve the powder: Run clumpy powder through a fine mesh sieve (100–150 mesh) to break up clumps and remove debris before loading into the cup. This solves many flow issues instantly.
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| APPLICATION PROBLEMS |
| Powder won’t stick to part | - Poor grounding — #1 cause: Without a proper ground circuit, the electrostatic charge has nowhere to go and powder won’t be attracted to the part. Verify twin grounding setup: dedicated 8-foot copper ground rod with one 12–18 gauge wire to the KV80/KV100 controller ground lug, and a second wire from the rod to the part or part holder. Both connections must touch bare, clean metal.
- Contaminated surface: Oil, grease, fingerprints, moisture, or residual chemicals on the part repel powder. Degrease thoroughly, perform a water sheen test, and handle only with nitrile gloves after cleaning.
- No electrostatic charge: Gun not charging (see “Gun not charging” above). Check electrode, controller, and cable connections.
- Part already coated: Powder over a fully cured, smooth first coat will struggle to adhere electrostatically. Reduce kV by ~50%, increase distance slightly, and ensure the ground clamp is on bare metal (file through the first coat at the contact point). Consider partial cure between coats instead of full cure.
- Humidity too high: Excessive moisture in the air reduces electrostatic adhesion. Ideally keep your coating area below 60% RH.
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| Back ionization (starring, rough texture on recoats) | - What it is: Back ionization occurs when excess electrical current (microamps) builds up on an already-coated or thick-coated surface. Trapped air ions erupt through the powder, creating a “starry night” or cratered texture. It’s a current problem, not a voltage problem.
- Too much kV for the application: On second coats or thick builds, reduce kV by 40–50%. The lower voltage produces less excess charge on the surface.
- No independent µA control: Guns with independent microamp adjustment (like the KV100) allow you to reduce current separately from voltage — the most effective way to prevent back ionization. If your gun doesn’t have independent µA control, lowering kV is your only option.
- Gun too close to part: Move back to 10–12 inches. Closer distance = more concentrated charge = more back ionization.
- Film build too thick: The thicker the powder layer, the more insulating it becomes, trapping more charge. Target 2–3 mils. Use a powder comb or mil gauge to check.
- Use a corona ring: The KV100 includes a built-in corona ring that removes excess free ions from the charge cloud — dramatically reducing back ionization. If your gun doesn’t have a corona ring, this defect will be harder to control on multi-coat work.
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| Faraday cage effect (powder won’t coat inside corners/recesses) | - What it is: Inside corners, channels, and enclosed areas create a Faraday cage where the electrostatic field concentrates on the outer edges and repels powder from the recesses. This is a physics problem that every coater faces.
- Reduce kV: Lower the electrostatic charge to reduce the field intensity that causes Faraday caging. On the KV80/KV100, the adjustable 0–100kV range lets you dial down as low as needed — even to 0kV to push uncharged free powder into deep recesses.
- Reduce µA (if available): On the KV100, independently reducing microamps while maintaining some kV is the most effective Faraday strategy.
- Increase distance: Move further back (12–14 inches). This widens the spray cloud and reduces field concentration.
- Use a corona ring: The KV100’s built-in corona ring strips excess free ions from the charge cloud, reducing the Faraday effect at its source.
- Spray recesses first: Coat the hard-to-reach areas first when the part has no powder on it (maximum conductivity), then coat the flat faces.
- Hot flocking (last resort): Preheat the part and spray uncharged powder into the recesses. The hot metal melts the powder on contact. Use sparingly — it’s easy to over-apply.
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| Thin coat / poor coverage | - Poor grounding: Inadequate ground = poor transfer efficiency. Verify twin grounding setup.
- kV too low: Insufficient charge means less powder attraction. Increase kV — the KV80 delivers 0–80kV and the KV100 delivers 0–100kV, giving you plenty of headroom.
- Gun too far from part: Beyond 12–14 inches, powder disperses too much and transfer drops. Close to 6–10 inches for most work.
- Powder flow too low: Increase the powder flow/air pressure on the gun. On the KV80/KV100, adjust the flow control valve to increase output.
- Moving too fast: Slow down your gun passes. Overlap each pass by 50% for even coverage.
- Wrong tip: A round tip on a large flat part is inefficient. Switch to a flat/fan tip for broad coverage.
- Excessive reclaim powder: Over-recycled powder loses its charge-holding ability. Mix reclaim with virgin powder (no more than 30–40% reclaim) or use fresh powder.
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| Too thick / runs / sags | - Over-spraying: Too many passes, too slow, or too close. Back up to 8–10 inches and make lighter, faster passes. Target 2–3 mils.
- Powder flow too high: Reduce the flow control valve. You need less powder than you think — especially on flat surfaces.
- Hot flocking too heavy: When hot flocking, powder melts on contact and true thickness is invisible. Use very light, sweeping passes.
- Stacking passes in one area: Don’t dwell on one spot. Keep the gun moving constantly with even, overlapping passes across the entire surface.
- Result: Excessively thick coatings run and sag during cure, show orange peel, have poor chip resistance, and can trap outgassing bubbles.
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| Picture framing (thick edges, thin center) | - Electrostatic wrap concentrating on edges: The electrostatic field wraps around sharp edges, depositing more powder there. Reduce kV to lessen the wrap effect.
- Aiming at edges: Spray the center/flat areas and let the electrostatic wrap carry powder to the edges naturally. Don’t aim directly at edges.
- Too much flow: High powder volume makes edge buildup worse. Reduce flow and make controlled passes across the face of the part.
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| Excessive overspray / poor transfer efficiency | - kV too low: Insufficient charge means powder doesn’t stick and becomes waste. Increase kV.
- Poor grounding: Without proper ground, powder isn’t attracted to the part efficiently. Verify twin grounding.
- Air pressure too high: Excessive air velocity blows powder past the part instead of depositing it. Reduce air pressure — most cup guns work best at 5–12 PSI.
- Gun too far from part: Move closer (6–10 inches) for better transfer.
- Poor booth airflow: Cross-drafts blow powder off the part. Ensure booth airflow draws away from the part, not across it.
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| Color cross-contamination | - Gun/hose not cleaned between colors: Residual powder from the previous color contaminates the new color. Blow out the gun, hose, cup, and nozzle thoroughly with compressed air between every color change. Disassemble the tip to check for packed powder.
- Booth contamination: Overspray from previous colors settles on booth walls and becomes airborne during the next job. Wipe down or blow out the booth between colors.
- Dedicated cups: Use separate cups for each color. The KV80 and KV100 use universally available 17 oz cups — keep extras on hand for fast color changes.
- Reclaim contamination: Recovered overspray from one color mixed into another. Use fresh virgin powder when color purity is critical, or maintain separate reclaim containers for each color.
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| FINISH DEFECTS (AFTER CURE) |
| Orange peel (rough, textured surface) | - Film too thin: Insufficient powder doesn’t flow out to a smooth film. Increase coverage to the manufacturer’s recommended 2–3 mils.
- Film too thick: Excessive thickness causes the coating to flow unevenly. Reduce coverage.
- Undercured: Insufficient time at PMT prevents full flow-out and crosslinking. Verify cure with an IR thermometer and MEK test.
- Overcured: Excessive time or temperature can cause the surface to wrinkle. Monitor PMT and pull on time.
- Back ionization: Excess charge disturbs the powder surface before cure. Reduce kV and µA (see back ionization section above).
- Outgassing: Gasses escaping from the substrate during cure disrupt the molten powder. Outgas porous parts before coating.
- Poor powder quality: Degraded, old, or moisture-contaminated powder won’t flow properly. Use fresh, properly stored powder.
- Oven temperature uneven: Hot and cold spots cause different sections to flow differently. Map your oven and avoid extreme zones.
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| Fish eyes / craters | - Silicone contamination — #1 cause: Even trace silicone from lubricants, sprays, rags, or aerosols will cause fish eyes. Enforce a strict zero-silicone policy in your coating area. Check all degreasers, lubricants, and sprays for silicone content. DEP Purple is silicone-free.
- Oil in compressed air: Oil from the compressor pump enters the air line and contaminates the powder. Install an oil coalescing filter and water separator on your air line. Drain the compressor tank daily.
- Surface contamination: Oil, grease, wax, mold release, or residual chemicals left on the part. Degrease thoroughly and perform a water sheen test before blasting.
- Outgassing: Trapped gasses in castings or galvanized parts erupt during cure. Pre-bake to outgas before coating, or use OGF primer.
- Incompatible powders: Mixing different powder chemistries (e.g., polyester overspray landing on an epoxy job) can cause craters. Clean equipment thoroughly between different powder types.
- Contaminated powder: Powder stored near silicone-containing products, or powder cross-contaminated with another chemistry. Test with a fresh bag of powder on a clean test panel to isolate.
- Use separate air hoses: Never use the same air hoses for powder coating and oiled air tools. Oil from tool lubrication contaminates the hose permanently.
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| Pinholes (tiny holes or pits in surface) | - Outgassing: Trapped gasses in castings, galvanized parts, or previously oily parts escape during cure, leaving tiny holes. Pre-bake/outgas the part before coating. Use OGF primer on stubborn castings.
- Moisture on part: Water trapped in weld seams, bolt holes, or surface pores turns to steam during cure. Ensure parts are completely dry — bake at 250°F for 10–15 min to drive off moisture before coating.
- Film too thick: Thick coatings trap gasses that can’t escape before the surface gels. Stay within recommended mil thickness.
- Contamination: Dirt, dust, or chemical residue on the surface. Improve cleaning and prep procedures.
- Poor oven exhaust: Inadequate oven ventilation allows cure gasses to concentrate and re-deposit on parts. Check exhaust is functioning.
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| Yellowing (especially whites, clears, pastels) | - Overbaking: Too much time at temperature or too high a temperature. Whites, yellows, reds, and clears are extremely sensitive. Cure at the low end of the TDS range and pull on time. See our Curing Guide for complete overbake prevention procedures.
- Film too thick: Thick films retain heat and continue curing after removal. Stay at 2–3 mils for color-sensitive powders.
- Mixed part sizes in oven: Thin parts overbake while heavy parts are still curing. Batch similar-mass parts together.
- Poor oven exhaust: Accumulated cure gasses in the oven cause yellowing, especially around part edges. Ensure proper ventilation.
- Oven hot spots: Parts near heating elements get hotter than the dial indicates. Map your oven and hang color-sensitive parts in the mildest zone.
- Low-temp cure is your friend: If your powder offers a low-temp cure window (e.g., 350°F for 20 min instead of 400°F for 10 min), use it for whites, yellows, and reds.
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| Chipping, peeling, or delamination | - Undercured: The coating never fully crosslinked and lacks hardness and adhesion. Verify cure with an MEK solvent rub test. If it fails, the part needs more time at PMT.
- Poor surface prep: Oil, grease, rust, or mill scale left on the surface prevents bonding. Strip, re-prep, and recoat. See our Surface Prep Guide.
- No mechanical profile: Smooth, un-blasted metal gives powder nothing to grip. Sandblast to create a 2–3 mil profile before coating.
- Delamination on multi-coat: The base coat was fully cured before the topcoat was applied, so there’s no chemical bond between layers. Use partial cure between coats — full cure only on the final coat.
- Incompatible base/topcoat: Different powder chemistries don’t always bond well. Test compatibility on a sample panel before committing to production.
- Film too thick: Excessively thick coatings have poor flexibility and chip more easily than properly applied 2–3 mil films.
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| Blisters / bubbles | - Outgassing: Trapped gasses in porous metals expand during cure, pushing through the molten coating. Pre-bake castings, galvanized, and oily parts to outgas before coating.
- Moisture trapped in part: Water in weld seams, between mating surfaces, or in bolt holes turns to steam during cure. Disassemble parts where possible. Dry thoroughly — bake at 250°F before coating.
- Chemical residue: Residual pretreatment chemicals or cleaning solvents that weren’t rinsed. Rinse thoroughly after all chemical treatments.
- Galvanized parts not pre-baked: Galvanized coatings trap significant moisture. Always pre-bake galvanized parts at 400–450°F for 45–60 min before coating.
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| Runs / sags / drips | - Film too thick: Excessive powder melts into a thick liquid that gravity pulls downward. Reduce application — target 2–3 mils.
- Hot flocking too heavy: Powder melts instantly on hot metal and true thickness is invisible. Use very light, quick passes.
- Part preheated too hot: If the part is excessively preheated (above cure temp) before coating, powder over-flows. Allow the part to cool closer to cure temp before spraying.
- Vertical surfaces: Gravity affects thick coatings on vertical surfaces more than horizontal. Apply thinner coats to vertical faces.
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| Soft finish / scratches easily (undercured) | - Insufficient time at PMT: The most common cause. The cure timer must start when the part metal reaches the specified temperature — not when you close the oven door. See our Curing Guide.
- Oven temperature too low: The oven dial may not match the actual air temperature. Verify with a separate oven thermometer.
- Heavy parts, short time: Thick, heavy parts take much longer to reach PMT than thin parts. The ramp-up time is not cure time.
- Test with MEK: Rub the cured surface with MEK-soaked cloth. Significant color transfer = undercured. Return to oven for additional time at PMT.
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| Dull / low gloss / hazy (blooming) | - Undercured: Many powders don’t reach full gloss until fully crosslinked. Verify cure with MEK test.
- Overcured: Excessive heat degrades gloss, especially on hybrids and epoxies. Monitor PMT and pull on time.
- Contaminated powder: Cross-contamination with another powder chemistry can cause gloss variation. Clean equipment thoroughly between powder types.
- Blooming: A hazy, foggy residue visible on darks (blacks, dark blues). Often caused by cheap resin, undercuring, or high humidity. Can sometimes be wiped off with a damp cloth. If persistent, switch to higher-quality powder.
- Film too thin: Very thin films may not develop full gloss. Build to recommended mil thickness.
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| Color mismatch / inconsistent color | - Uneven film thickness: Thick areas look darker; thin areas look lighter. Apply even, consistent coats and check with a mil gauge.
- Overcured in some areas: Hot spots in the oven shift color in those zones. Map your oven and rotate parts if needed.
- Mixed powder batches: Different lots of the same color can have slight variation. Use one batch per job when color matching is critical.
- Cross-contamination: Even tiny amounts of another color affect the visible shade. Clean equipment thoroughly between colors.
- Different substrate metals: The same powder can look slightly different over steel vs. aluminum due to different heat absorption and surface characteristics.
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| Uneven metallic / mottled metallic finish | - Inconsistent film thickness: Metallic flakes concentrate differently at different thicknesses, causing mottling. Apply even, consistent passes.
- kV too high: High voltage can cause metallic flakes to orient inconsistently. Reduce kV and increase distance slightly.
- Back ionization: Excess charge disturbs metallic flake orientation. Reduce kV and µA. Use a corona ring if available (KV100).
- Gun too close: Concentrated spray pattern doesn’t let metallics distribute evenly. Back up to 10–12 inches.
- Reclaim powder issues: Recycled metallic powder loses flake content relative to base. Limit reclaim usage for metallics to 20–30%.
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| Powder spits / lumps / seeds / dirt in finish | - Clumped powder: Moisture or heat-damaged powder fires out as lumps. Sieve powder through 100–150 mesh before spraying.
- Dirty gun: Old powder buildup inside the gun body breaks loose and spits out. Disassemble and clean after each use.
- Environmental contamination: Dust, lint, grinding debris, or fibers from clothing landing on the part or in the powder. Keep your coating area clean. Wear lint-free clothing. Blow off the part immediately before spraying.
- Oven contamination: Debris inside the oven falls onto parts during cure. Clean the oven interior regularly.
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| Wrinkling / crinkle texture (unintended) | - Excessive film thickness: Very thick films cure unevenly — the surface skins over while the underlayer is still liquid, causing wrinkles as gasses escape. Reduce film build.
- Oven temperature too high: Extreme heat causes the surface to gel before the underlayer flows, trapping gasses. Reduce oven temperature to the lower end of the TDS range.
- Incompatible powders mixed: Two different powder chemistries accidentally mixed can create a wrinkle effect. Clean equipment thoroughly between powder types.
- Note: Some powders are intentionally formulated to produce a wrinkle/vein texture. If you didn’t intend a wrinkle finish, check that you’re using the correct powder.
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| Foaming on surface | - Film too thick: Most common with urethane and some polyester powders. Thick films trap volatile byproducts from the crosslinking reaction (Ecap in urethanes), which foam at the surface. Reduce film build to recommended thickness.
- Moisture in part or powder: Water vapor creates foam-like bubbling during cure. Dry parts thoroughly. Check powder for moisture contamination.
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| Inconsistent gloss across part | - Uneven film thickness: Different thicknesses cure at different rates and develop different gloss levels. Apply uniformly.
- Oven hot spots: Areas of the part closer to heating elements overcure and lose gloss. Map your oven and use baffles if needed.
- Mixing powder batches: Different lots may have slight gloss variation. Use single batch per job.
- Contamination: Residual powder from a previous color or chemistry affects gloss. Clean equipment thoroughly.
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| Clear coat milky / hazy / yellowed | - Film too thick: Clear coats applied too heavily lose clarity and appear milky or opaque. Clear coats are designed for thin application — typically 1.0–2.0 mils.
- Overbaked: Excess time or temperature causes yellowing and haze in clears. Cure at the low end of the TDS range.
- Poor oven exhaust: Accumulated gasses cause discoloration, especially around edges. Ensure proper ventilation.
- Contamination: Cross-contamination with colored powders creates a tinted or cloudy appearance. Use dedicated equipment for clear coat work.
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| ENVIRONMENT & STORAGE PROBLEMS |
| Moisture in air supply | - No water separator/filter: Compressed air contains water vapor that condenses as it cools. Install a water separator and oil coalescing filter on the air line between the compressor and the gun.
- Compressor tank not drained: Water accumulates in the bottom of the tank. Drain it before every session — make it a habit.
- Long air hose runs: Long hoses allow more condensation. Keep hoses as short as practical and use a dryer near the gun end if runs are long.
- High humidity days: Compressors produce more moisture in humid conditions. Consider a refrigerated or desiccant air dryer for production environments.
- Symptoms: Pulsing/sputtering powder, clumping, spitting, pinholes, craters, and poor charging are all linked to moisture in the air supply.
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| High humidity affecting coating | - Reduced electrostatic efficiency: Humid air is more conductive, which bleeds charge from the powder cloud. Increase kV to compensate (the KV80’s 80kV and KV100’s 100kV provide headroom for this).
- Powder absorbs moisture: Open containers of powder absorb atmospheric humidity. Keep containers sealed. Discard powder that feels clumpy or has been exposed for extended periods.
- Dehumidify your space: A portable dehumidifier in your coating area can dramatically improve performance on humid days. Target below 50–60% RH.
- Flash rust: High humidity causes freshly blasted steel to flash-rust quickly. Coat as soon as possible after blasting, or pre-treat with iron phosphate to buy time.
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| Degraded / expired powder | - Storage conditions: Powder should be stored below 77°F (25°C) in a sealed container, away from direct sunlight and moisture. Shelf life under proper conditions is typically 1 to 2 years.
- How to test: Pinch a small amount between your fingers. Fresh powder should be fine, free-flowing, and smooth like flour. If it clumps, feels gritty, or doesn’t disperse when dropped, it’s compromised.
- Symptoms of degraded powder: Poor flow, poor charging, pulsing, orange peel, low gloss, and inconsistent color.
- When to discard: If sieving and fresh storage don’t restore flowability, the powder has been damaged by heat or moisture and should be discarded. Don’t waste time trying to salvage badly degraded powder — the cost of rework exceeds the cost of new powder.
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