Troubleshooting tips for finishing problems
April 8, 2022 | 12:26 pm CDT
Chemcraft

Example of fish eyes. Photo courtesy of Chemcraft.

Here are some common finishing problems and how to solve them.

Problem: Bénard cells: Cell pattern in the finish; color and surface irregularities.
Solutions: Add dispersant; add silicone additive to reduce surface tension; increase application viscosity; lower application thickness; add thixotrope or thickener.

Problem: Blooming: Hazy deposit on film; oily or wax-like substance on surface; reduced gloss; mottled or non-uniform surfaces.
Solutions: Adjust catalyst level – over–catalyzation; do not use stearated materials such as lacquers and certain polyesters under acid catalyzed coatings; check formula for incompatibility; check substrate for contamination.

Problem: Blushing: Whitening of surface; lowering of gloss.
Solutions: Reduce humidity; use richer thinner; check the water level in equipment; warm lacquer to room temperature; increase the temperature of application area; slow dry time; dry waterborne stains or sealers.

Problem: Cold check; cracks in finish.
Solutions: Decrease dry film build; ensure minimum room temperature during cure; use only freshly catalyzed material; ensure correct catalyzation; ensure profiles are sanded to reduce sharp angles.

Problem: Cratering: Depressions in finish with raised edges and material at center.
Solutions: Clean substrate and equipment before application; filter material; check/clean air system and ventilation control; addition of silicone flow agent.

Problem: Crawling: Formation of beads, islands, craters or pinholes; poor wetting of substrate.
Solutions: Clean substrate before application; ensure sanding before application; addition of silicone flow agent.

Problem: Fish eyes: Depressions in the finish with raised edges and uniform material at the center; undispersed droplets in paint.
Solutions: Remove the source of contamination or incompatibility; clean substrate and equipment before application; clean air system and ventilation control; addition of silicone flow agent.

Problem: Floating: Mottled, blotchy or streaked appearance; separation and uneven distribution of pigment; the result of Bénard cell formation.
Solutions: Increase application viscosity; lower application thickness; add thixotrope or thickener; add dispersant; add silicone additive to reduce surface tension.

Problem: Orange peel: Surface bumpiness or waviness; poor leveling.
Solutions: Check and/or lower viscosity; apply correct or thicker film build; reduce dry spray or overspray; increase atomizing air; reduce fluid pressure; check correct air cap; use retarder solvent or rich thinner; eliminate excessive air movement; add silicone flow agent; apply an even stroke with a spray gun at the correct distance.

Problem: Sagging: Gravity-driven flow on vertical surfaces.
Solutions: Speed up the solvent balance; control or reduce the application of material; increase application viscosity; correct spray application, avoid overlap, use correct gun angle, speed, gun movement; apply several thinner coats; reduce drafts and application in direct sunlight; increase temperature of application area; reduce application nozzle size; reduce fluid pressure.

Problem: Tearing: Large cracks in the waterborne finish; uneven drying of the surface before the body of the paint film; poor through cure in waterborne materials.
Solutions: Decrease surface heat to finish; increase substrate temperature.

Problem: Telegraphing: Structural or surface features revealed in the finish; show-through of fingerprints, water spots or sanding marks.
Solutions: Addition of silicone flow agent; increase the viscosity of coating; addition of thixotrope; faster solvent balance.

Source: Chemcraft/AkzoNobel. For information, call 336-841-5111 or visit Chemcraft.com. More troubleshooting tips and videos in the Tools tab online at Chemcraft.

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