Selection of coating additives (easy to learn)

Principles for selecting coating additives:

Avoid adding additives if possible
High efficiency
Minimal negative impact
High cost-effectiveness
Environmentally friendly

Selection method of coating additives : Coating additives are a relatively important component in coating formulations. Although the dosage is usually small (0.1%~5%), they have a significant impact on the storage stability, construction performance, film-forming effect and final paint film properties of the coating.

Main categories and functions of coating additives

Dispersants	Improve pigment dispersion and prevent sedimentation and flocculation	Polyacrylates (such as BYK-190) 、 phosphates (such as Tego Dispers 750W)
Wetting Agents	Reduce surface tension and improve substrate wetting	Silicones (such as Tego 270), acetylenic diols (such as Surfynol 104)
Defoamers	Inhibit foaming and reduce coating defects	Mineral oils; silicones (such as Tego Foamex 810 )
Leveling agents	Improve coating leveling and reduce orange peel and brush marks	Acrylates (such as BYK-358) and silicones
Thickeners	Adjust paint viscosity to prevent sagging and settling	Cellulose ethers (such as HEC), polyurethanes (such as RM-2020), bentonite (such as Bentone SD-1),
Anti-settling agents	Prevent pigment settling and improve storage stability	Anti-settling agents Prevent pigment settling and improve storage stability Fumed silica (such as Aerosil 200), polyamide wax (such as Disparlon 6900-20X)
Curing accelerators	Accelerate coating curing and improve reaction efficiency	Organotin (such as DBTDL), amines (such as DMP-30), Shurui 400 (acid catalyzed)
Light stabilizers	Prevent UV degradation and improve weather resistance	UV absorbers (such as Tinuvin 1130), HALS (such as Tinuvin 292)
Mold inhibitors	Inhibit mold growth and extend the life of the coating	Isothiazolinones (such as Kathon LXE) and benzimidazoles (such as Preventol A4)
Adhesion promoters	Improve the adhesion between the coating and the substrate	Silane coupling agents (such as KH-550), epoxy phosphates

Key factors in additive selection

Coating system (waterborne/solventborne/UV curing):

For water-based coatings, choose a water-soluble or water-dispersible additive (such as BYK-190 dispersant or Tego Wet 270 wetting agent).

For solvent-based coatings, choose an oil-soluble additive (such as BYK-161 dispersant or BYK-011 defoamer).

For UV-curing coatings, choose a photoinitiator-compatible additive (such as Tego Rad 2100 leveling agent).

Coating Type (Primer/Topcoat/Clearcoat/Basecoat):

Primer: Focus on adhesion promoters and rust inhibitors (such as zinc phosphate).

Topcoat: Focus on leveling agents, matting agents (such as silica matting powder), and weathering agents (such as Tinuvin 1130).

Basecoat: Water-based coating dispersants (such as BYK-190) and anti-settling agents (such as Aerosil 200).

Application Method (Spray/Brush/Roller):

Spraying: Requires a low-foaming additive (such as FoamStar ED 2521) and a leveling agent (such as TEGO Airex 904w).

Brush/roller coating: Requires an anti-sagging additive (such as Bentone SD-1) and an anti-splatter additive (such as Rheolate 299).

Environmental and performance requirements

Demand	Recommended additives
Highly weatherable	UV Absorber (Tinuvin 1130) + HALS (Tinuvin 292)
High gloss	Leveling agent (BYK-358) + Defoamer (TEGO Rad 2500)
Matte/Frosted	Matting powder (TS-100) + Anti-settling agent (Aerosil 200)
Antibacterial and mildew-proof	Mold inhibitor (Kathon LXE) + algaecide (Preventol A4)
High adhesion	Epoxy phosphate (BASF Irgafos 168) + silane coupling agent (KH-550)

Verify long-term stability:
Perform accelerated aging testing (e.g., 30 days at 40°C) to observe for:
Settling (adjust anti-settling agent);
Viscosity change (adjust thickener);
Decrease in defoaming properties (defoamer hydrolysis);

Another important consideration is the compatibility of additives with the binder system：
Many additives possess specific chemical structures and molecular weights to achieve their intended functions. Coating binders (such as resins) are also high-molecular-weight substances with specific structures and molecular weights. The two must be well-matched for the additive to function effectively.

Common Problems and Solutions

Common Problems	Possibility Analysis	Solutions
Craters in the coating film	Leveling or defoamer incompatibility	Replace with a more compatible additive (e.g., Tego Foamex 810)
Pigment settling	Insufficient dispersant/anti-settling agent	Add anti-settling agent (e.g. Aerosil 200)
Poor leveling	Improper leveling agent selection	Switch to a silicone leveling agent (such as BASF Efka 3030 、3031)
Excessive foaming	Wetting agent is highly foaming	Adjust defoamer (e.g., BASF MO2190、2410AC)
Poor adhesion	Insufficient substrate wetting	Add an adhesion promoter (such as BASF Lupasol SK)

Conflicts and contradictions between the properties of specific additives and other coating properties:

Anti-sagging agents – improve coating leveling
Defoamers – reduce cratering
Slip agents – improve recoatability
Coating additives – improve stain resistance (high boiling point, prone to retention)
Emulsifiers – residual emulsifiers can affect coating water resistance
Photoinitiators – residual photoinitiators can cause yellowing

When using additives, be sure to understand their negative effects. Good food doesn’t need any seasoning, so avoid it if possible! Otherwise, it can be counterproductive.