Catalyzed Clear Coat/Topcoat Problems
- Correct and accurate mix ratio of paint, activator and reducer.
- Selection of appropriate speed ingredients for prevailing weather conditions.
- Adequate air temperature throughout curing period.
- Sufficient air movement throughout initial curing period.
- Correct millage of products being applied.
- Correct flash times between coats.
- Quality and selection of spray equipment.
Problem: Hazing – A condition where the paint finish slightly dulls out within the first 24 hours after being applied.
- Cause: System closing too rapidly on the surface therefore preventing solvent from evaporating correctly. Solution: Extend flash times by selecting slower activators and/or reducers in warm weather.
- Cause: Evaporated solvent landing back on freshly painted surface therefore dulling paint finish. Solution: Since solvent vapor (evaporated solvent) is heavier than air and falls toward the ground there must be significant exhaust movement in the paint area to pull the solvent off the paint surface and away from the vehicle.
- Cause: Solvents laying too long on surface of vehicle therefore dulling paint finish. Solution: Select faster speed activator and/or reducer to prevent solvents from laying on paint surface during curing period. Use faster activator/reducers for cooler weather conditions. If possible improve air flow over vehicle during curing period.
Problem: Dieback – A condition where the paint surface dulls down, may show sand scratches or have a grainy appearance. This condition takes place anywhere between two (2) weeks and six (6) months after application.
- Cause: Inadequate film build. Solution: Be sure to apply the correct amount of topcoat paint. Amount of sanding and buffing should be considered in order to determine proper level of topcoat. Viscosity of topcoat should be checked to be sure it falls within recommended level.
- Cause: Topcoats, primers, sealers were not sufficiently dry before subsequent coats were applied. Solution: Be sure that flash times, dry times are strictly adhered to in order to avoid trapped solvent.
- Cause: Too much film build up of primers. Overuse of primers to fill surface defects. As primers cure out, over time, they pull down into defects and topcoat is pulled down therefore showing defect. Solution: Sufficiently repair surface defects (scratches etc.) so as not to require surface of primers. Overuse of primers will not allow primer to completely cure before topcoats are applied. Do not apply primer surfacers in heavy coats. Apply medium coats as needed with correct flash time between coats.
- Cause: Inferior quality primer and/or sealers. Topcoats penetrate down into undercoats. Solution: Use only high quality 2-component primers and sealers so as to have adequate solvent resistance and prevent topcoats from penetrating down into primers. Lacquer or acrylic primers are generally not recommended under catalyzed urethane finishes.
Problem: Solvent Pop – A condition caused by trapped solvent migrating up to the surface of the coating and then turning into vapor. One of two things will happen when solvent vaporizes before it is released, it will either blow a hole in the topcoat which is too far cured to re-flow or it will form a small blister beneath the cured paint surface.
- Cause: Using activators or reducer that is too fast for prevailing weather conditions. Solutions: Use slower activator and/or reducer combination. Slower solvents will allow coating to actually cure-through.
- Cause: Too much film build, especially prevalent when applying LOW V.O.C. and HIGH SOLIDS coatings. however, can take place when too many coats are applied. Solution: Use only the recommended number of coats with proper flash times between coats.
Solution: Use only high quality current technology spray equipment.
Quality: Older paint guns and/or cheap spray guns will spray large particle sizes therefore making it easy to over build film while trying to make coating flow newer technology spray guns will break paint up and allow coating to lay flat and flow easier. This will also allow coating to cure much faster.
Fluid Tip Selection: It is critical that the correct fluid tip nozzle set is used to break the paint up correctly. Large fluid nozzles (above 1.5mm) should not be used to apply topcoats.
Cause: Use of accelerators during warm weather condition. Accelerators cause the chemical reaction to speed up therefore risking solvent entrapment.
Solution: Do not use accelerator in temperatures above 70 degrees F. Chemical cross-linking is severely hampered at temperatures below 60 degrees F. Accelerators can be useful in these conditions.
Problem: Delamination – This is a condition where the topcoat finish, whether it be clear coat or color, becomes detached from the previously applied coating.
- Cause: Topcoat is applied beyond the recommended window period established by the color-coat manufacturer. Solution: Be sure to apply topcoat within the time frame allowed, also do not apply topcoats before the recommended flash time for color.
- Cause: Reducer used in color system flashed too fast therefore preventing color from drying through completely. Solution: Topcoat must be able to lay wet long enough to adequately adhere to color-coat. Slower solvents will allow topcoat to adhere better.
Problem: Cloudy Appearance In Clear Coat – This condition normally happens when moisture is introduced to the coating during mixing or application or after coating is applied.
- Cause: Moisture most commonly is introduced through air lines during the application process. Solution: Use a high quality inline air drying system. Also use of desiccant disposable air filters that attach to the handle of application equipment will help insure dry air.
- Cause: Vehicle being exposed to extremely high humidity and/or rain within the first 12 hours after application of coating. Solution: All vehicles should be kept in a stable low moisture environment for at least 8 hours after application of coating. Moisture will cross-link with hardener and therefore produce a cloudy appearance.
Problem: Soft Coating After Overnight Dry – Paint system remains soft and will mar or fingerprint easily after overnight dry. This condition also prevents coating from buffing.
- Cause: Improper hardener to paint mix ratio. Solution: Be sure to mix components exactly to the mix ratio recommended by coating manufacturer.
- Cause: Insufficient temperature during first 8-12 hours after application. Solution: Allow vehicle to remain in area that is kept at no less than 65 degrees F for first 8 hours after application.
Problem: Clear Coat Wrinkling or Lifting Between Coats
- Cause: Previous coat has begun chemically cross-linking before subsequent coat was applied.
Solution: Flash time between coats was too long. Be sure to apply coats within the time frame designated by coating manufacturer.
Solution: In extremely hot humid conditions use a retarding solvent to hold coating open longer and allow solvent to evaporate.