During the production, mixing, and application of water-based coatings, a large number of bubbles are easily generated due to factors such as raw material ratio, high-speed dispersion, and air entrainment. Many paint manufacturers choose the right water-based paint defoamer, but due to improper addition methods, problems such as incomplete defoaming, repeated foaming, coating delamination, film formation and pinholes occur, which not only waste chemicals but also affect product quality and construction efficiency. Huide Defoamer is deeply involved in the field of defoamers, and based on years of industry experience, it provides a detailed breakdown of the correct methods for adding defoamers to water-based coatings. It is suitable for various water-based coating scenarios, helping manufacturers avoid adding misconceptions and effectively achieve defoaming effects.
1、 Preparation before adding defoamers to water-based coatings
The effectiveness of adding defoamers to water-based coatings depends first and foremost on the preparation work before addition, which directly affects the subsequent defoaming efficiency and is also a detail that many manufacturers tend to overlook. By doing these two steps well, 80% of the addition problems can be reduced.
Confirm that the type of defoamer for water-based coatings is suitable for different types of water-based coatings (such as water-based latex paint, water-based wood paint, water-based industrial paint, water-based waterproof paint), and the corresponding defoamer type is different. Before adding, it is necessary to confirm that the selected defoamer is compatible with the coating system (for example, water-soluble defoamers should be preferred for water-based systems to avoid delamination caused by the use of oil-based defoamers).
Defoamer pretreatment (as needed): For high viscosity water-based coatings or when the viscosity of the defoamer itself is high, the defoamer can be diluted with deionized water or a diluent in the coating system in a ratio of 1:2~1:5, stirred evenly, and then added. This can help the defoamer disperse more quickly into the coating, avoiding shrinkage and loss of gloss caused by excessive local concentration. Diluted defoamers should be prepared and used immediately, and should not be stored for a long time to prevent failure.
2、 Core addition method of defoamer for water-based coatings
The addition of defoamers for water-based coatings needs to be adjusted according to different production and construction scenarios, with a focus on controlling the timing, amount, and mixing method of the addition. The specific operations for different scenarios are as follows, to meet the production and construction needs of various coatings.
（1） Add during the production phase (main nodes that determine the basic defoaming effect)
The production stage is the main link in the generation of bubbles, and adding them correctly can stabilize the bubbles from the source. It is divided into three key nodes, and the timing of addition can be selected as needed:
In the early stage of dispersion and grinding of water-based coating raw materials, 40% to 50% of the total addition amount is added. At this point, adding bubbles can stabilize the dispersion process in advance, avoiding the difficulty of eliminating large amounts of bubbles that are difficult to eliminate. It is especially suitable for high-speed dispersion of pigments and fillers, which can reduce subsequent defoaming pressure.
Mid stage addition (paint adjustment stage) involves adding 30% to 40% of the total amount added during the viscosity adjustment and dilution process of the coating. At this point, the coating system tends to stabilize, and the addition of defoamers can quickly eliminate the bubbles generated during the paint mixing process. At the same time, it can stabilize the regeneration of bubbles during subsequent storage and transportation, making it suitable for water-based coatings that require high film flatness (such as home latex paint and water-based wood paint).
In the later stage (finished product stage), 10-15 minutes before the completion of coating production, add the remaining 10% to 20% of defoamer for additional defoaming to ensure that the finished coating has no bubbles and a uniform texture, and to avoid floating bubbles and delamination during storage.
（2） Add during the construction phase (supplement defoaming to ensure construction effectiveness)
During the construction process of some water-based coatings (such as spraying, rolling, brushing), secondary bubbles may be generated due to mixing and construction pressure, and targeted defoamers need to be added. The specific method is as follows:
Spray coating construction: Before construction, add 0.05%~0.1% defoamer (calculated based on the total amount of coating) to the finished coating, stir evenly before spraying, which can avoid bubbles caused by high-pressure air entrapment during the spraying process and prevent pinholes and rough surfaces in the paint film.
Roll coating/brush coating construction: If bubbles are found on the surface of the coating during construction, a small amount of defoamer can be added (no more than 0.03% each time), gently stirred evenly before continuing construction to avoid excessive mixing and re entrainment of air.
Large scale construction: For large-scale construction scenarios such as walls and floors, an appropriate amount of defoamer can be added to the coating in advance, and the mixing speed can be controlled during the construction process to reduce the generation of bubbles and ensure a smooth and even paint film.
（3） Add quantity control (core misconception: more is not better)
The amount of defoamer added to water-based coatings needs to be strictly controlled. Excessive addition can cause shrinkage, loss of gloss, and decreased adhesion of the coating. Insufficient addition cannot achieve the defoaming effect. The reference amount for different scenarios is as follows (can be adjusted according to the number of bubbles):
Ordinary water-based coatings (such as water-based latex paint, water-based primer): the addition amount is 0.1% to 0.3% of the total coating amount;
High viscosity water-based coatings (such as water-based wood coatings and thick coat waterproof coatings): the addition amount is 0.3%~0.5%;
Severe bubble scenarios (such as high-speed dispersion and high solid content coatings): can be appropriately increased to 0.5%~0.8%, but not exceeding 1%, to avoid affecting the performance of the coating;
（4） Mixing method of water-based paint defoamer: gentle and uniform, avoiding secondary foaming
After adding defoamers, the stirring method is crucial. Incorrect stirring will once again draw in air, leading to defoaming failure:
Mixing speed: Control at 500-800r/min to avoid high-speed mixing (exceeding 1000r/min) and prevent large amounts of air from being mixed in;
Mixing time: After each addition, stir for 3-5 minutes to ensure that the defoamer is evenly dispersed in the coating system without local accumulation;
Attention: During mixing, avoid hitting the container wall with the mixing blade to reduce air entrapment. After mixing, let it stand for 5-10 minutes to allow residual bubbles to dissipate naturally.
3、 Common misconceptions about adding (avoid these, double the defoaming effect)
Many manufacturers use water-based paint defoamers with poor effectiveness, which is not a product issue, but rather a trap in adding them. The following four common misconceptions must be avoided:
Misconception 1: The more defoamers added, the better. Excessive addition can cause shrinkage, loss of gloss, and even affect film formation, waterproofing, and adhesion of the coating. Fine tune according to the amount added;
Misconception 2: Adding too late and waiting for a large number of bubbles to form before adding increases the difficulty of defoaming. It is necessary to increase the amount of addition, but the effect is not good. It is recommended to start adding in the early stages of production;
Misconception 3: Directly adding high viscosity defoamers without dilution leads to uneven dispersion of defoamers, excessive local concentration, and shrinkage. High viscosity defoamers need to be diluted in advance;
Misconception 4: If the mixing speed is too fast and the air is sucked in again, it will counteract the defoaming effect. Strictly control the mixing speed and time.
4、 Precautions for adding defoamers to water-based coatings
Storage: Finished coatings with added defoamers should be stored in a sealed manner, avoiding direct sunlight and high temperature environments to prevent defoamer failure. The storage temperature should be controlled between 5-35 ℃;
Construction environment: Avoid high temperature and high humidity environments during construction. High temperature can accelerate the evaporation of defoamers, while high humidity can cause bubbles to appear on the surface of the paint film, affecting the defoaming effect;
Compatibility testing: When using a new defoamer, a small batch compatibility test needs to be conducted first to confirm that there are no issues such as delamination or shrinkage before adding it in bulk.
The correct addition method is the key to the effectiveness of water-based coating defoamers, which can completely solve the problem of bubbles, ensure the quality of coating film formation, reduce raw material waste and production costs. Huide Defoamer focuses on the research and production of water-based coating defoamers. We not only provide specialized defoamers that are suitable for various water-based coatings, but also customize exclusive addition plans based on the manufacturer's production process and coating type. We provide free guidance on addition operations to help manufacturers easily solve bubble problems, improve product quality and production efficiency.
Post time: Jul-20-2026