In resin flooring and floor coatings, priming is not an “option,” but the foundation of durability. It is the layer that bonds the substrate to the system, stabilizes absorption, and reduces the risk of defects (bubbles, craters, delamination). Simply put: you can have the best topcoat, but without a good primer, the system has nothing to “work” on.
Why primer is mandatory
- Binds dust and strengthens the concrete surface zone after grinding/milling.
- Evens out absorption, so subsequent layers do not “disappear” in places in the substrate.
- Builds adhesion for the system (paint/coating/flooring) and improves resistance to delamination.
- Reduces the risk of pores and craters, because it seals the surface and limits concrete “outgassing.”
- Facilitates consumption control and improves the repeatability of the visual effect.
When G1 + U1 (standard conditions and typical projects)
In standard projects (stable conditions, typical temperatures, normal humidity), a classic epoxy primer of type G1 is most often used in combination with the U1 hardener as the first step of the system. Its task is always the same: to saturate, bind, and prepare the substrate for subsequent layers.
Practical conclusion: if someone asks “is primer necessary?” – the answer is yes. The question should be: what primer and what application scheme to choose for the conditions and system.
When G2 + MTB (QF): the best primer for winter and colder conditions
In winter, most problems do not stem from “worse resin,” but from conditions: lower temperature, higher humidity, and the risk of condensation (dew point). Therefore, in colder projects, we recommend a systemic approach: EPIDIAN® FLOOR QF, where the primer layer is G2 + MTB hardener (high reactivity and fast curing, a solution designed for lower temperatures).
QF system structure (simply)
- Substrate: concrete.
- Primer: EPIDIAN® FLOOR G2 + MTB hardener.
- Base layer: EPIDIAN® FLOOR G2 + U1 hardener.
- Top layer: EPIDIAN® FLOOR G2 + U1 hardener.
Winter = dew point control (this is more important than a “magic product”)
With higher humidity and falling temperatures, surface defects (clouding, cratering, tackiness) may appear. The most dangerous scenario is condensation on the substrate, i.e., reaching the dew point temperature. If micro-droplets of water form on the surface, the adhesion of the system drops. Therefore, the substrate temperature must be at least 3°C higher than the dew point temperature.
Winter instructions: priming step by step (proven, without guesswork)
- Conditions measurement: measure the substrate temperature, air temperature, and relative humidity; make sure the substrate is at least +3°C above the dew point.
- Concrete preparation: the substrate must be clean, dry, absorbent, and rough; remove cement milk, paints, grease/oils; after mechanical treatment, vacuum thoroughly.
- Mixing (QF): prepare small portions, adjusted to the pace of work; do not make a “spare bucket.”
- QF primer (G2+MTB): apply evenly with a roller/brush/float so that the primer is absorbed into the concrete and does not form puddles; consumption is adjusted to absorption.
- 1 or 2 primer layers: prime less absorbent substrates once, more absorbent substrates twice (the second layer after the first has fully cured).
- Time before the next layer: leave the primed substrate to cure and only then proceed to the base layer.
- “Winter sure-fire” option: you can sprinkle freshly primed concrete with 0.4–0.8 mm quartz sand, which facilitates the application and leveling of the base layer (remove the excess after curing).
Most common winter mistakes (and how to avoid them)
- Lack of dew point measurement: solution: measure and maintain a +3°C margin on the substrate.
- Large portions of mixture: solution: make small portions and work quickly, according to the pot life.
- “Warm during the day, cold at night”: solution: stabilize conditions during curing (without drafts and sudden temperature drops).
- Primer “in puddles”: solution: the primer must penetrate the concrete, not form local accumulations.
What to choose: G1 + U1 or QF (G2 + MTB)?
If conditions are stable and you are doing a typical project: the classic G1 + U1 scheme will most often work. If it is cold/chilly, humid, and the risk of condensation is increasing: choose the systemic QF approach with G2 + MTB primer and strict dew point control.
Related products (making it easier to complete the system)
FAQ
Can I skip the primer if the concrete is “strong”?
It is not worth it. Even strong concrete has dust and uneven absorption after treatment. Primer stabilizes the substrate and creates adhesion; without it, the risk of delamination and surface defects increases.
Why do defects occur so often in winter?
Because humidity increases, temperature drops, and it is easier to reach the dew point (condensation). In addition, resin mixtures lose “workability” faster in uncontrolled conditions.
What is the most important parameter to control in winter?
Dew point: the substrate must be at least +3°C above the dew point temperature, otherwise condensation reduces adhesion and ruins multi-layer applications.
Want to choose a primer and calculate consumption for your flooring? Write to us: surface area (m²), type of facility (garage/warehouse), concrete condition, temperature, and humidity on site. We will select the system (G1+U1 or QF: G2+MTB) and advise on a safe technology.
