5. Raw materials: what each formulation component does
1. Polyaspartic ester resin is a key starting point
The resin supplies amine-functional sites for curing. Molecular structure, functionality, equivalent weight, viscosity and reactivity influence application and film formation. Differences between resin grades extend beyond speed: even with similar pot lives, mixed viscosity, early hardness, flexibility and color behavior can differ.
Suppliers list amine value, equivalent weight, viscosity and supply form separately because these parameters answer different questions. Covestro’s raw-material handbook illustrates this classification. Covestro polyaspartic raw-material handbook
2. The hardener does more than make the coating dry
Polyisocyanate hardeners build the film’s network, with structure and functionality affecting how it connects. HDI and IPDI are common abbreviations associated with hardener chemistry, but commercial hardeners are often derivatives or prepolymers. Polymeric industrial coating hardeners should not be confused with the corresponding monomers.
Selection must also consider viscosity, reactive-group content, free monomer and resin compatibility. Replacing a hardener without recalculating the ratio and verifying pot life and performance can disturb the formulation’s balance. Similar names or appearances do not make hardeners interchangeable.
3. Pigments affect color, hiding and stability
Coloring pigments provide color, while certain pigments also contribute to hiding, optical effects or other functions. Uniformity depends on dispersion, interactions between pigments and film thickness as well as dosage. Different colors based on the same resin may still require separate appearance and weathering assessment.
A clear topcoat is not necessarily the same colored product with the pigment removed. Clear finishes reveal haze, bubbles and changes in the underlying color more readily. Pigmented finishes must address hiding, floating, flooding and color consistency. Different development objectives usually require different formulation details.
4. Fillers have functions beyond cost reduction
Fillers can adjust rheology, mechanical behavior, texture and volume composition. Particle size, shape, surface treatment and moisture condition can influence film compactness and application. Treating every filler as adulteration, or assuming more filler is always better, misses its formulation role.
Assess whether the filler serves the application. A smooth, clear finish has different needs from a textured coating or a thicker intermediate layer. Resin–filler interfaces, loading and dispersion quality matter more than simply asking whether filler is present.
5. Small amounts of additives can change film formation
Wetting and dispersing additives help establish and maintain the dispersion of solid particles in a liquid. Defoamers and deaerators address bubbles. Leveling and surface additives adjust spreading, surface condition and aspects of feel. Rheology additives balance flow, settling resistance and sag resistance. These names describe primary functions, not identical results in every formulation.
Additives can interact. A change that improves slip may require a fresh recoat assessment; a stronger defoaming approach may introduce cratering or compatibility issues. Adding a supposedly universal additive on site is generally an unreliable repair strategy. Evaluate formulation changes through a coordinated set of tests.
6. Matte and hammered finishes require dedicated surface design
Matte finishes require control of gloss and its uniformity, potentially involving matting components, dispersion and surface microstructure. Hammered finishes require control of pattern formation and the curing window. Matting agents, texture-control components and other pigments and fillers need to work as a validated combination.
Junaimei polyaspartic matte and hammered-finish topcoats should therefore not be understood as ordinary topcoats modified on site with a powder or additive. Users should select a finished grade matched to the desired effect and follow the approved application process.
7. Solvents and reactive diluents are different
Nonreactive solvents primarily adjust application behavior and evaporate during film formation. Reactive diluents can become part of the network but also affect reaction proportions and final properties. A solvent-free formulation does not make all low-viscosity components interchangeable.
Do not improvise dilution with water, alcohol or a cleaning solvent at hand. A liquid suitable for cleaning tools is not necessarily a suitable coating thinner. Where adjustment is necessary, use only materials and methods expressly allowed for the product.