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Solutions for Defects in UV Wood Coatings (Part 4)

Release time:

2026-03-18 17:31

Solutions for Defects in UV Wood Coatings (Part 4)

During the application of UV wood coatings, various factors—including equipment, materials, processes, and environmental conditions—often give rise to defects such as pinholes, poor leveling, and uneven gloss. These issues not only compromise the aesthetic quality of the finished product but may also reduce its weather resistance and service life. This paper addresses the common problem of pinholes in UV wood coating applications by proposing specific remedial measures, while briefly discussing strategies for addressing other types of defects.

I. Source Control of Bubble Origins

Bubbles are the primary precursors to pinhole formation, and controlling the bubble content in the paint formulation is the first and most critical step in preventing pinholes.

1. Optimize the coating circulation system: Install buffer zones and low-velocity flow sections within the circulation system to minimize turbulence. Select low-shear-rate circulation pumps to prevent high-speed rotation from generating air bubbles. Design the return pipeline to allow flow along the vessel wall, thereby preventing the coating liquid from striking the liquid surface and entraining air.

2. Optimize the static settling defoaming process: After formulation, the coating should be allowed to stand for an adequate period to enable entrapped air bubbles to rise and rupture naturally. For high-viscosity coatings, the standing time may be appropriately extended, or vacuum degassing equipment may be used to assist in defoaming.

3. Control the stirring intensity and method: Use low-speed stirring or planetary stirring to minimize air entrainment. The stirring blades should be immersed to a sufficient depth below the liquid surface to prevent surface vortices from drawing in air.

II. Pre-treatment for Release of Base Material Gases

The air trapped within wood vessels expands and is released upon heating, serving as a major source of pinholes.

1. Strengthen substrate sealing: Apply a highly penetrative sealer as a primer to pre-treat the surface, allowing it to infiltrate the wood vessels and form a dense barrier that blocks the pathways for internal air to escape.

2. Control of preheating temperature and time: Prior to coating, the substrate should be preheated to release the air trapped in the wood vessels. Coating should be applied as soon as possible after preheating to prevent reabsorption of moisture.

3. Optimize coating structure design: Use multiple thin coats instead of a single thick coat to facilitate the complete release of entrapped gases before curing. Allow sufficient dwell time between each coat to ensure that all trapped gases have fully escaped.

III. Precise Control of Solvent Evaporation

If the thinner evaporates too quickly or at the wrong time, it can rapidly vaporize within the paint film, rupturing the surface and resulting in pinholes.

1. Select the appropriate type of thinner: Based on the coating system and the ambient temperature during application, choose a thinner with a moderate evaporation rate to strike a balance between leveling time and evaporation characteristics.

2. Control the temperature in the leveling section: Maintain the leveling temperature within an appropriate range to facilitate the orderly evaporation of solvents. Ensure adequate ventilation in the leveling section to promptly remove the evaporating solvent vapors.

3. Adjust coating thickness and curing schedule: Control the thickness of each coat appropriately to prevent excessive buildup. For thick-coat applications, adopt a staged curing process: first perform low-energy pre-curing to allow sufficient gas release, followed by full curing.

IV. Rational Use of Defoaming Additives

Introducing defoaming additives into paint formulations is an effective method for suppressing pinholes.

1. Select an appropriate defoaming agent: Choose a defoamer that is compatible with the coating system and the root cause of pinholes; if necessary, multiple defoamers can be blended for use.

2. Control the dosage of defoamer: Determine the optimal dosage through gradient testing, balancing defoaming performance with coating film properties and avoiding adverse effects such as cratering caused by overdosing.

3. Pay attention to the addition sequence and dispersion method: Defoaming agents should be added at an appropriate stage during paint formulation, and thorough dispersion must be ensured to prevent excessive stirring from degrading the active ingredients.

V. Optimization and Matching of Curing Conditions

Control of the curing process directly influences the time competition between gas escape and surface sealing.

1. Properly configure the curing energy: Based on the coating properties and film thickness, precisely set the UV lamp power, irradiation distance, and conveyor speed to achieve a dynamic equilibrium between surface curing and gas release.

2. Employ a gradient curing process: first apply low-energy irradiation to induce preliminary gelation of the coating film, thereby preserving gas-evacuation pathways; after sufficient gas release, complete the full cure with high-energy irradiation.

3. Control the temperature and humidity of the curing environment: Maintain the curing environment within an appropriate range and keep it stable to prevent excessively high temperatures that can lead to overly rapid reactions, or excessively high humidity that may cause side reactions.

VI. Conclusion

Defects such as pinholes that occur during the application of UV wood coatings not only compromise the aesthetic quality of the product but may also degrade its performance and service life. By thoroughly analyzing the root causes of these defects and implementing targeted corrective measures, coating quality and product competitiveness can be effectively enhanced. In actual production, it is essential to continuously draw lessons from experience, optimize coating processes, and refine equipment maintenance and management procedures to ensure the stability and reliability of UV wood coating quality.

Disclaimer: The above content is sourced from the internet and is provided for reference only. If any infringement occurs, please contact us, and we will remove it promptly.

Boxing Recommended Products – UV Wood Coatings
Putty primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
Sanding primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
Apply primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-02	Phosphate ester acrylate	Enhances adhesion to substrates such as metal, glass, and plastic.
B-05	Phosphate ester acrylate	Enhances adhesion to substrates such as metal, glass, and plastic.
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
B-535	Polyester acrylate	Excellent adhesion, rapid curing, good flexibility, and yellowing resistance.
B-546	Polyester acrylate	Good adhesion, fast curing, and excellent flexibility.
White primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
B-529	Polyester acrylate	Good adhesion, low shrinkage, and excellent resin compatibility.
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
Gloss topcoat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-21C	Active amine photosensitizing promoter	Low color number, antioxidant and polymerization inhibitor, and enhanced curing rate
B-301	Aromatic Polyurethane Acrylate	Fast curing, good toughness, and excellent grindability.
B-302	Aromatic Polyurethane Acrylate	Fast curing, high strength, good toughness, and excellent grindability.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-601	Aromatic Polyurethane Acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost performance.
B-609	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch resistance, and chemical resistance.
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-910A2	Aliphatic polyurethane acrylate	Low viscosity, yellowing resistance, chemical resistance, and steel-wool resistance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Matte topcoat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-21C	Active amine photosensitizing promoter	Low color number, antioxidant and polymerization inhibitor, and enhanced curing rate
B-328M	Aliphatic polyurethane acrylate	Low gloss, low viscosity, excellent wettability, and a pleasant hand feel.
B-328R	Aliphatic polyurethane acrylate	Low gloss, excellent matting, good wetting, and a fine, smooth, and silky hand feel.
B-333	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, good wetting properties, and excellent flexibility.
B-572	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-650A	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, fast curing, and good wettability.
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-910A2	Aliphatic polyurethane acrylate	Low viscosity, yellowing resistance, chemical resistance, and steel-wool resistance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Bright White Finish
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-301	Aromatic Polyurethane Acrylate	Fast curing, good toughness, and excellent grindability.
B-302	Aromatic Polyurethane Acrylate	Fast curing, high strength, good toughness, and excellent grindability.
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-601	Aromatic Polyurethane Acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost performance.
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Adherent
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-05	Phosphate ester acrylate	Enhances adhesion to substrates such as metal, glass, and plastic.
B-509B	Polyester acrylate	Good adhesion, good flexibility, and excellent pigment wetting.
B-531	Polyester acrylate	Good adhesion, impact resistance, excellent flexibility, and yellowing resistance.
B-535	Polyester acrylate	Excellent adhesion, rapid curing, good flexibility, and yellowing resistance.
B-546	Polyester acrylate	Good adhesion, fast curing, and excellent flexibility.
B-590	Polyester acrylate	Excellent adhesion, rapid curing, and good pigment wetting.
Filler type
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
B-529	Polyester acrylate	Good adhesion, low shrinkage, and excellent resin compatibility.
Color correction
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
Harden
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-301	Aromatic Polyurethane Acrylate	Fast curing, good toughness, and excellent grindability.
B-302	Aromatic Polyurethane Acrylate	Fast curing, high strength, good toughness, and excellent grindability.
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-601	Aromatic Polyurethane Acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost performance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Matte
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-328M	Aliphatic polyurethane acrylate	Low gloss, low viscosity, excellent wettability, and a pleasant hand feel.
B-328R	Aliphatic polyurethane acrylate	Low gloss, excellent matting, good wetting, and a fine, smooth, and silky hand feel.
B-329D	Aliphatic polyurethane acrylate	Low irritation, low viscosity, excellent wettability, and a pleasant feel.
B-333	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, good wetting properties, and excellent flexibility.
B-650A	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, fast curing, and good wettability.
Solid-color paint
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-519	Self-curing polyester acrylate	Self-initiated photopolymerization performance
B-530	Polyester acrylate	Low viscosity, excellent hydrophobicity, thixotropy, and improved ink misting
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
Yellowing resistance
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-431	Cycloaliphatic Specialty Acrylates	Yellowing resistance, excellent wettability, low viscosity, and fast curing
Dip coating
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
Roll coating
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-100	Bisphenol A epoxy acrylate	High hardness, high gloss, excellent chemical resistance, and high fullness.
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
Solvent-free spraying
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-251	Aromatic Polyurethane Acrylate	Fast curing, excellent flexibility, and good wetting of black ink pigments.
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
LED-UV
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-21C	Active amine photosensitizing promoter	Low color number, antioxidant and polymerization inhibitor, and enhanced curing rate
B-241	Aliphatic polyurethane acrylate	Fast curing, excellent skin feel, and yellowing resistance.
B-27	Active amine photosensitizing promoter	Low color number, benzene-free, low odor, antioxidant and anti-polymerization
B-570	Polyester acrylate	Low viscosity, benzene-free, low odor, suitable for LED UV
B-574	Polyester acrylate	Benzene-free, low odor, and VOC levels meet cigarette pack standards.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
Excimer lamp
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-241	Aliphatic polyurethane acrylate	Fast curing, excellent skin feel, and yellowing resistance.
Skin feel
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-241	Aliphatic polyurethane acrylate	Fast curing, excellent skin feel, and yellowing resistance.
B-328M	Aliphatic polyurethane acrylate	Low gloss, low viscosity, excellent wettability, and a pleasant hand feel.
B-328R	Aliphatic polyurethane acrylate	Low gloss, excellent matting, good wetting, and a fine, smooth, and silky hand feel.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
Single-item recommendation
Product Model/English Abbreviation	Product Name/Product Type	Product Features
BM2223/TPGDA	Di(propylene glycol) diacrylate	Good flexibility and low volatility
BM2224/EO-HDDA	Ethoxylated 1,6-hexanediol diacrylate	Good adhesion to plastics, good dilutability, and low volatility.
BM3231/TMPTA	Trimethylolpropane triacrylate	High crosslink density, high hardness, high gloss, and excellent wear resistance.
BM3235/PET3A	Pentaerythritol triacrylate	Fast curing, high crosslink density, high hardness, and excellent chemical resistance.
BM3380/3EO-TMPTA	Tripropylene Glycol Triacrylate	More flexible and less irritating than TMPTA.
BM6261/DPHA-80	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.
BM6263/DPHA-90	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.

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Solutions for Defects in UV Wood Coatings (Part 5)

Solutions for Defects in UV Wood Coatings (Part 3)