Lesson 16. Reaction‑Curing Systems (“Liquid Armor”)

We have reached the final block of our course dedicated to the skeleton of decorative material — the binder. We have studied in detail two large groups: mineral binders and film‑forming dispersions. Now, to complete the picture, we move on to the third specialized category — reaction‑curing systems.

In this lesson we will examine what reaction‑curing systems are and which types of binders belong to this group. We will also look at the specific features of working with them, defined by the chemical processes that occur during their application.

Reaction‑curing systems are binders that harden not through simple evaporation of water or solvent, but as a result of an irreversible chemical reaction. Typically, these are two‑component (2K) systems consisting of a base (resin) and a hardener. After mixing, a process begins that transforms the liquid components into an extremely strong polymer network. They are used where maximum strength and durability are required.

This group has two key representatives:

• Polyurethane resins — leaders in combining wear resistance and elasticity.
• Epoxy resins — champions in hardness, chemical resistance, and adhesion.

Regardless of whether you work with polyurethane or epoxy, the chemical reaction dictates specific rules for the craftsman:

• Pot life: After mixing components A and B, you have a strictly limited time (e.g., 30–60 minutes) to apply the material. After this, the reaction progresses so far that the mixture becomes unusable right in the bucket.
• Mixing accuracy: The proportions of components must be followed with laboratory precision. An error means the reaction will not proceed correctly, and the coating may never harden or remain sticky forever.
• Independence from air humidity: Unlike water dispersions, which require evaporation, curing of 2K systems depends mainly on temperature (the warmer, the faster the reaction).

Thanks to this curing mechanism, all coatings in this group have a unique set of characteristics: exceptional strength, high chemical resistance, monolithic structure, virtually zero shrinkage, and excellent adhesion.

It is important to understand that both polyurethane and epoxy systems can be produced in three different forms, directly affecting application method, safety, and final properties:

• Solvent‑based: The “classic” type, where resin and hardener are dissolved in volatile organic solvents (xylene, acetone, etc.). Solvent reduces viscosity and improves penetration into dense mineral substrates. After application, two processes occur: solvent evaporation and chemical curing. These options have a strong, toxic odor and require strict safety measures (ventilation, respiratory protection).
• Solvent‑free: Modern high‑tech formulations without volatile components. The entire volume of mixed material converts into solid phase, creating thick, durable coatings with virtually zero shrinkage. Environmentally friendly, odorless, but often highly viscous, making application more difficult. Ideal for self‑leveling floors and thick protective coatings.
• Water‑based: The most eco‑friendly and convenient form. Resin and hardener particles are dispersed in water. After application, water evaporates, allowing particles to come together and trigger the chemical reaction. Almost odorless, tools can be cleaned with water (before curing). Considered the safest for interior work. In strength and chemical resistance they may be slightly inferior to solvent‑free and solvent‑based analogues, but for most residential and commercial tasks their properties are more than sufficient.

In the next lesson we will examine polyurethane and epoxy resins separately to better understand their composition and application features.