When selecting a water-based paint defoamer, a comprehensive evaluation must be conducted based on the paint
system's characteristics, production process, performance requirements, and cost. Below are the key selection criteria
and specific recommendations:
I. Clarify Core Requirements: Matching Defoamer Type with Performance
1.Select the type based on defoaming mechanism. Water-based coating defoamers are mainly divided into three categories,
each with its applicable scenarios:
Silicone-based defoamers (e.g., polydimethylsiloxane)
Advantages: Extremely fast defoaming speed, long-lasting antifoaming effect (typically several hours to days), and broad
applicability.
Limitations: Moderate compatibility; excessive addition may lead to surface shrinkage and reduced gloss (especially in high-gloss
coatings), and may decompose and volatilize at high temperatures (>150°C).
Applicable scenarios: solvent-based coatings, thick-film systems requiring long-term defoaming (such as industrial paints), and
high-temperature baking coatings (select "heat-resistant modified silicone" for these).
Polyether defoamers (such as polyoxyethylene-polyoxypropylene ethers)
Advantages: Excellent compatibility (miscible with water and resins), minimal impact on coating gloss and adhesion, no risk of
shrinkage, and good environmental friendliness (low VOC).
Limitations: Moderate defoaming speed, relatively short bubble suppression duration (typically tens to a few hours), requiring
formulation with other components to enhance efficacy.
Applicable scenarios: latex paint, high-gloss coatings (such as water-based wood finishes), and systems with high compatibility
requirements (such as colored paints and varnishes).
Mineral oil/alkyl alcohol defoamer
Advantages: Lowest cost, direct defoaming effect, suitable for low-demand scenarios.
Limitations: Poor compatibility, prone to migration and phase separation, may affect paint leveling, requires use with dispersants.
Applicable Scenarios: General architectural coatings, primers (non-glossy, low-gloss systems).
2. Core performance indicators
Defoaming speed: Quickly defoam during mixing (choose organic silicone), slowly defoam before construction (choose polyether).
Anti foaming time: During the production process, it is necessary to prevent foaming for a long time (such as stirring and grinding
latex paint). Choose a strong anti foaming agent (organic silicon>polyether>mineral oil); If only temporary defoaming is required
before construction, the requirement for foam suppression can be reduced.
Compatibility: By conducting a "compatibility test" (adding defoamers to the coating base material to observe for turbidity,
delamination, or shrinkage), defects such as "oil shrinkage" and "flower formation" caused by poor compatibility can be avoided.
II. The selection of different types of water-based coatings (such as latex paint, water-based industrial paint, water-based wood
paint, etc.) based on the characteristics of the coating system has significant differences in the requirements for defoamers.
The recommended defoamer type for the resin system of the coating type is based on the key considerations of latex paint,
styrene acrylic, pure acrylic resin polyether (such as RK-8413), and mineral oil that needs to be resistant to electrolytes (latex
paint contains a large amount of pigments and fillers). Choosing polyether is more stable. Water based industrial paints such
as epoxy, polyurethane, acrylic organosilicon (such as RK-8405), and polyether compound high-temperature baking systems
require the selection of "modified organosilicon" (such as fluorinated or ester based). Waterborne wood paint with water-based
PU, water-based NC polyether (such as RK-3062E), and organic silicon (low addition) to avoid affecting gloss (choose low
concentration organic silicon or pure polyether). Water based paints/varnishes prioritize compatibility with amino resins,
epoxy ester polyethers, and polyether modified organosilicon to avoid affecting leveling and transparency.
III.Key auxiliary factors: environmental protection, temperature, cost, and regulations
1. Environmental Protection and Regulations
VOC and environmental certification: Low VOC or VOC free defoamers (such as polyether and modified
organosilicon) should be preferred, especially when used in food packaging, medical devices, and other fields, and must
comply with FDA, NSF, and other food contact material certifications.
Biodegradability: If used in environmentally demanding scenarios such as water-based leather and fabric coatings, choose
biodegradable polyether defoamers.
2. Temperature adaptability
Room temperature system (such as latex paint, ordinary coatings): Conventional polyether or mineral oil is sufficient.
High temperature baking system (>100 ℃): "High temperature resistant modified organosilicon" (such as treated with silane
coupling agent to reduce high temperature volatilization) should be selected to avoid "pinholes" and "residual bubbles"
caused by the decomposition of defoamers.
3. Cost balance
Low cost requirement: Mineral oils (such as white oil-based defoamers), but subject to poor compatibility issues.
Mid to high end demand: Polyether based (cost-effective) or polyether modified organosilicon (with good comprehensive
performance and moderate cost).
High end demand: Organic silicon with good performance, but at a higher price (usually 5-10 times that of mineral oil).
IV.Practical suggestion: small-scale validation+compound optimization
Trial screening
Take a small amount of coating base material, add 0.1% -0.5% defoamer (based on the total weight of the coating),
simulate production conditions (such as high-speed stirring, sanding), and observe:
Defoaming time: the time required for foam to disappear (<30 seconds is fast);
Foam suppression time: whether the foam is regenerated after 2 hours;
Appearance: Whether there are defects such as shrinkage, discoloration, and delamination.
Compound use
A single type of defoamer may not meet all needs, and can be compounded:
Polyether+mineral oil: improves compatibility and reduces costs;
Polyether+Organosilicon: Balancing defoaming speed and compatibility (such as 1:1 compounding, suitable for high
gloss coatings).
Adding method
It is recommended to pre disperse the defoamer with a small amount of water or resin before adding it to the coating system to
avoid aggregation caused by direct addition (especially solid defoamers).
The core logic for selecting water-based coating defoamers is to first clarify the coating system (resin, pigment and filler, temperature)
and performance requirements (defoaming speed, gloss, environmental protection), then verify compatibility and actual effects through
small-scale experiments, and finally balance cost and stability. For example:
High gloss latex paint → polyether (such as RK-3062E);
High temperature baking industrial paint → heat-resistant silicone (such as RK-8411);
Low cost ordinary coatings → mineral oils (such as RK-8402).
