Defects in surface treatment can be caused by the substrate, coating, working conditions, and most often it is a combination of all these causes.

Reasons

• The lacquer is insufficiently levelled (oversized droplets)
• A large temperature difference between the lacquer and the surface
• Incorrect pressure when lacquering or incorrect distance from the surface
• The temperature and air velocity in the room are too high
• Drops of lacquer that are too dry fall onto the workpiece

Prevention

• Lower the viscosity, increase the pressure, and use a smaller nozzle
• Check and adjust the temperature difference between the lacquer and the surface
• Set the spray gun and follow the instructions
• Lower the temperature and air circulation rate
• Use a slow thinner, check the distance between the workpiece and the spray gun, increase the flow of the lacquer

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Excessive amount of lacquer in one coat, application of several coats of lacquer with too little intermediate drying, the lacquer is too thick
• The temperature and air circulation rate in the room are high or the evaporation time is too short
• Incorrect thinner
• Wood/substrate humidity, substrate temperature are too low
• The distance between the spray gun and the workpiece is too small, the viscosity is too high due to the low lacquer temperature

Prevention

• Adjust the application, intermediate drying time, viscosity
• Follow the instructions for use
• Lower the temperature and air velocity in the room, extend the drying time by adjusting the conveyor speed
• Increase the moisture of the wood/substrate, pre-temper the substrate
• Use the right spraying method, thin the lacquer, increase the lacquer temperature to the prescribed limit

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Insufficiently dried UV water coating before UV curing
• Excessive intensity of UV lamps

Prevention

• Increase the temperature in the dryer
• Increase the speed of the belt in UV dryer
• Reduce the intensity of UV lamps
• Extend the drying time of the coating
• Apply a thinner layer of coating

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Unsuitable viscosity of the material, the thickness of the applied material is too small or too large
• The distance between the spray gun and the element is too small, incorrect spraying angle, the pressure is too high
• Unsuitable spray nozzle size
• The temperature of the lacquer, substrate or lacquer room is too low

Prevention

• Follow the instructions for preparing the application material
• Spray in several thin layers with intermediate venting
• Check the settings of the spraying equipment
• Control and use the recommended nozzles
• Temper (heat) the substrates, material and space

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• The lacquer’s viscosity is too high and the substance is dry
• Incorrect choice of thinner or insufficient amount
• Incorrect pressure when lacquering or incorrect distance from the surface
• High air speed and high temperature in the drying room
• The wood is too porous

Prevention

• Check the suitability of the lacquer and lower its viscosity
• Use the recommended thinner in the correct amount
• Set the spray gun and follow the instructions
• Adjust the temperature and air circulation settings
• Apply insulation or a thinner lacquer layer with the first application

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• The substrate is unclean (dirt, dust, grease)
• Natural resins and waxes in the wood (pine, exotic wood, etc.), melamine film
• The base lacquer coat is too thick and the base surface is over-sanded (overly fine sanding)
• Insufficient sanding of the base/interlayer sanding
• Mismatch between the base and the final lacquer
• Droplets of the lacquer are too dry when they fall on the workpiece
• Too much time has elapsed between the sanding and the lacquering

Prevention

• Clean and degrease the surface
• Use the recommended insulation, sand the foil before applying the lacquer
• Smaller application of the lacquer, lower spray pressure
• Check the sandpaper quality (wear and tear)
• With machine sanding, keep an eye on the pressure and temperature to prevent overheating of the sanded lacquer coat
• Use compatible materials
• Use a slow thinner, check the distance between the workpiece and the spray gun, increase the flow of the lacquer
• Repeat the sanding and dust removal

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• The surface is contaminated with wax, grease, silicone (gloves, hand cream)
• Compressed air contaminated with condensate or oil residue
• Use of silicone polishing agents or sprays in the vicinity of the spray booth

Prevention

• Check the filters, clean the compressed air inlet pipe system
• Remove silicone polishing agents and use non-silicone agents

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Uneven spraying of the lacquer
• The amount of old mix added to the new lacquer is too large
• The base is damaged or the primer is over-sanded
• The lacquer is poorly mixed in the bucket
• The substrate temperature is too high (due to overheating), the lacquer temperature is too low during application

Prevention

• Check the equipment and settings
• Check the viscosity of the old material and add a new (fresh) lacquer mix
• Remove any faults (putty) on time and apply another coat of primer
• Ensure a proper mixing method – mixer
• Adjust the temperature of the substrate and lacquer

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Too much material in one coat
• The final lacquer is applied too quickly, the base coat is not properly dry
• Unsuitable combination of the base and the final lacquer
• Inadequate thinner was used

Prevention

• Check the viscosity and control the application
• Ensure that each coat is sufficiently dried before applying the next
• Use compatible materials
• Use recommended thinners

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• The lacquer is aired too slowly compared to the drying, which causes air bubbles to remain trapped in the film
• The humidity in the air and lacquer room is too high
• The final lacquer is applied too quickly
• The base lacquer has not completely wet the pores (to the bottom)
• The wood’s accessory components do not accept the lacquer (common with PE lacquers)

Prevention

• Use an anti-foaming agent and/or slower thinner
• Control the humidity, lower as required, and use a thinner adapted for such conditions
• Dry the bottom coat (primer) sufficiently before applying the next coat of lacquer
• Use a base lacquer with good wetting ability
• Use special insulation on problematic species of wood (especially exotic species such as teak, rosewood, etc.)
• Apply a layer of PU lacquer/insulation before applying the PE lacquer

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Water-based lacquer or enamel is not suitable for oak, beech, ash, alder
• Water-based lacquer is not suitable for treating wood with a large amount of resin (spruce, pine, etc.)

Prevention

• Apply a suitable lacquer or enamel for the type of wood used or use a discoloration blocker
• Use a suitable lacquer/enamel or. impregnation to block the resin

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Paraffin, wax or machine lubricants on the surface

Prevention

• Clean the surface before surface treatments
• Caution in the use of lubricants in production

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations

Reasons

• Excessive film thickness of the lacquer
• Using the wrong hardener
• Humidity is too high
• Improper drying, poor storage conditions
• The mixture pot-life has expired
• Unsuitable primer or lacquer

Prevention

• Apply a thinner layer of lacquer
• Check the hardener in the mixture
• Reduce the humidity level
• Check the drying method and storage conditions
• Use a fresh lacquer mixture
• Use a suitable primer or lacquer

Solution

• Sand the surface down to the base/substrate
• Re-apply the lacquer according to the recommendations