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Short answer: an epoxy floor does not dry at a single moment; curing happens in successive stages, and the times depend on the product and the temperature. For example, the self-leveling epoxy DEMCO EPOX 2000 SELF is dry to the touch in 8–10 hours at 23 °C, must not come into contact with water for 24 hours after application, and reaches full cure in an average of 7 days when applied at 20–25 °C. The fast-curing DEMCO EPOX 2004 SELF/FAST, on the other hand, can be opened to traffic within 5–6 hours at 20–23 °C.
The times and conditions below are taken from the technical data sheets of DEMCO primers and floor coatings; for each value, the temperature it refers to is stated.
What does "dry" mean? The stages of curing
Two-component epoxy and polyurethane coatings do not dry in air like paint; they harden through the chemical reaction that starts when components A and B are mixed. The data sheets give the stages of this process separately:
- Pot life: the time the mix can be worked in the container. The data sheets ask you to mix only as much as you need and to keep working until all of it is used.
- Touch dry: the surface no longer feels tacky, but the floor is not yet ready for loads.
- Recoat time: when the next coat can be applied. Some data sheets also set an upper limit: with DEMCO PUR 363 SELF, the wait between coats is 10–24 hours at 23 °C; if this is exceeded, the surface is sanded.
- Foot and vehicle traffic: when people can walk on the floor and vehicles and forklifts can drive on it. Only some data sheets give this separately.
- Full cure and chemical resistance: when the coating reaches its mechanical and chemical resistance.
- First contact with water: the earliest time water, moisture and condensation may reach the surface.
Cure times in the data sheets
| Product | Pot life | Touch dry | Recoat | Full cure | Water contact |
|---|---|---|---|---|---|
| DEMCO EPOX 100 PR (primer) | 20–40 minutes | 10–12 hours | 2–4 hours (epoxy coat) | 1 week | None for the first 24 hours |
| DEMCO EPOX 114 PR – FAST (fast moisture barrier primer) | 20–40 minutes | 8–10 hours | 2–4 hours (epoxy coat) | 1 week | – |
| DEMCO EPOX 2000 SELF | 50–90 minutes | 8–10 hours | – | 1 week | None for the first 24 hours |
| DEMCO EPOX 2004 SELF/FAST | 13–20 minutes | 3–4 hours; hard dry 5–6 hours | – | 1 week | None for the first 24 hours |
| DEMCO EPOX 150 TOP COAT (epoxy topcoat) | 60–100 minutes | 5–7 hours | – | 1 week | None for the first 24 hours |
| DEMCO PUR 350 SELF (polyurethane) | 40–70 minutes | 8–10 hours | 24 hours | 1 week | None for the first 24 hours |
| DEMCO PUR 410 TOP COAT UV/S (polyurethane topcoat) | At least 4 hours | 3–5 hours | 8–24 hours | 1 week | None for the first 24 hours |
| DEMCO PUR 303 CONCRETE/W (PU concrete) | 20–30 minutes | – | At least 24 hours after the primer | Average of 7 days | – |
Pot life refers to 23 °C and a 100 ml mix; touch-dry and recoat times come from the data sheets' 23 °C drying tables. The data sheets of DEMCO EPOX 114 PR – FAST, DEMCO EPOX 2004 SELF/FAST and DEMCO PUR 303 CONCRETE/W do not state a temperature for these times. In all of these data sheets, full cure is an average of 7 days at room temperature for a product applied at 20–25 °C. If a polyurethane coat goes on top of the two primers, wait until the primer is touch-hard; according to the data sheets this takes at least 12–24 hours at 15–30 °C. A "–" means the data sheet gives no value for that stage.
When can you walk on it, and when can vehicles drive on it?
The data sheets of DEMCO EPOX 2000 SELF and DEMCO EPOX 150 TOP COAT give no separate foot or vehicle traffic time; two limits from the data sheet apply: do not touch the surface for the first 24 hours, and full cure takes an average of 7 days at 20–25 °C. In between, decide with our technical team when to open the floor to loads and traffic, based on the temperature on site.
If the floor must reopen quickly: DEMCO EPOX 2004 SELF/FAST can be opened to traffic within 5–6 hours at an ambient and substrate temperature of 20–23 °C. Because its pot life is short, it is applied quickly and spike-rolled within about 10 minutes; the data sheet specifies DEMCO EPOX 114 PR – FAST as the primer underneath.
Three PU concrete data sheets list the load stages separately for 30 °C; according to the data sheets, these are average, indicative values and may vary with site conditions.
| Product (30 °C) | Application time | Light foot traffic | Light traffic | Medium traffic | Heavy traffic | Full chemical resistance |
|---|---|---|---|---|---|---|
| DEMCO PUR 303 CONCRETE SL 23 UT/WB (topcoat) | 15 minutes | 16 hours | 24 hours | – | 48 hours | 7 days |
| DEMCO PUR 303 CONCRETE SL31 COVING/WB (leveling and coving mortar) | 15 minutes | 8 hours | 24 hours | – | 48 hours | 7 days |
| DEMCO PUR 303 CONCRETE NANO ESD/WB (antistatic) | 15–20 minutes | 12 hours | 36 hours (light vehicles) | 48 hours | 7 days | 7 days |
Application time is the time after the mix is poured onto the floor. SL31 COVING/WB must always be coated with SL 23 UT/WB once it has cured, so the final coat determines when the finished floor can be opened to traffic.
Full cure and chemical resistance
Touch dry does not mean full strength; in practice, chemical exposure and wet or machine cleaning start after full cure. For the three PU concrete products above, full chemical resistance is reached in 7 days at 30 °C. The data sheet of DEMCO EPOX 192 NOVOLAC TOPCOAT, used on floors exposed to highly concentrated acids, alkalis and solvents, gives a drying time of 24 hours and full cure in 1 week, and asks you to consult our technical team about chemical resistance conditions and prolonged contact.
First contact with water: the 24-hour rule
The data sheets of most products in the first table require that the surface is not touched and does not come into contact with water for 24 hours after application. This is the earliest point at which water contact may begin; it does not mean full resistance. Some data sheets ask for more:
- DEMCO EPOX 192 NOVOLAC TOPCOAT is protected from moisture, condensation and water for at least 24 hours.
- DEMCO PUR 303 CONCRETE NANO ESD/WB is protected from outside moisture, condensation and water for at least 4 days; the floor is covered with a breathable material such as kraft paper, not polyethylene sheeting.
- With SL 23 UT/WB and SL31 COVING/WB, the substrate and the coated surface are kept at least 3 °C above the dew point for 48 hours after application.
How do temperature and humidity affect the times?
Data sheet values refer to a specific temperature (23 °C, 20–25 °C or 30 °C). Low temperatures slow curing down; touch-dry, recoat, traffic and full cure times all get longer. High temperatures shorten the pot life, so the mix has to be used faster. The DEMCO PUR 363 SELF data sheet also states that the time between coats gets longer at low temperatures and shorter at high temperatures.
For products such as DEMCO EPOX 2000 SELF and DEMCO PUR 350 SELF, the temperature in the work area must be 15–30 °C, and the substrate must never fall below 10 °C. With SL 23 UT/WB, do not apply if the air or surface temperature will drop below +5 °C during application or curing.
The data sheets of DEMCO EPOX 2000 SELF and 150 TOP COAT and of DEMCO PUR 350 SELF, 410 TOP COAT UV/S and 303 CONCRETE/W require substrate moisture below 4%; the ambient humidity limit is 80% for these epoxies and 65% for these polyurethanes. SL 23 UT/WB and SL31 COVING/WB are not used where relative humidity is above 75%. For measurement, see Concrete moisture before epoxy.
Frequently asked questions
When can you walk on an epoxy floor?
It depends on the product. The DEMCO EPOX 2000 SELF data sheet gives no separate foot traffic time and asks that the surface is not touched for the first 24 hours. DEMCO EPOX 2004 SELF/FAST can be opened to traffic within 5–6 hours at 20–23 °C. For PU concrete, the light foot traffic time at 30 °C is 16 hours for SL 23 UT/WB and 12 hours for NANO ESD/WB.
When can vehicles drive on an epoxy floor?
Only some data sheets give this time. At 30 °C, SL 23 UT/WB withstands light traffic after 24 hours and heavy traffic after 48 hours; for NANO ESD/WB, light vehicle traffic is 36 hours and heavy traffic 7 days. For other products, decide the opening time with our technical team. For parking garages, see Parking garage flooring.
Does epoxy cure in cold weather?
It cures within the temperature range in the data sheet, but more slowly as the temperature drops. The DEMCO EPOX 2000 SELF data sheet gives a working temperature of 15–30 °C, and the substrate must not fall below 10 °C. In cool weather, every stage takes longer than the data sheet values. If heating is needed, the DEMCO EPOX 192 NOVOLAC TOPCOAT data sheet recommends electric heaters that blow warm air.
When can an epoxy floor be washed?
According to most data sheets, no water should reach the surface for the first 24 hours; for NANO ESD/WB, this is at least 4 days. In practice, wet and machine cleaning start after full cure. For details, see Epoxy floor coating maintenance and cleaning.
How many days does an epoxy floor take to cure fully?
There is no single number of days; full cure is given product by product. The data sheets of the products in the first table give an average of 7 days (1 week) when applied at 20–25 °C; for the three PU concrete products, full chemical resistance takes 7 days at 30 °C. At lower temperatures, it takes longer.
Tell us how the floor will be used, the date it must reopen to traffic, and the temperature and humidity on site in the quote form, and our technical team will recommend a product and waiting times that fit your schedule. For the application steps, see How to apply an epoxy floor coating, and browse our flooring products.
