The curing time of polyurethane waterproof coating varies depending on the type (single component or two-component) and environmental conditions, and is usually affected by the following factors:
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I. Curing time range
1. Single component polyurethane coating
- Surface drying time: about 4-8 hours (touch dry and not sticky).
- Actual drying time: 24-48 hours (completely cured).
- Relying on moisture in the air for curing, which may be extended when the ambient humidity is low.
2. Two-component polyurethane coating
- Surface drying time: 2-4 hours.
- Actual drying time: 12-24 hours.
- Curing through the chemical reaction of the main agent and the curing agent, the speed is faster.
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II. Factors affecting curing time
1. Temperature
- Temperature increase (such as above 25°C): accelerates the reaction and shortens the curing time.
- Temperature reduction (such as below 10°C): significantly prolongs the curing time, and even leads to incomplete curing.
2. Humidity
- Single-component coatings: Depends on ambient humidity (60%-80% recommended). Too low humidity will delay curing.
- Two-component coatings: Humidity has little effect, but high humidity may cause condensation on the surface, affecting the quality of the coating.
3. Coating thickness
- Too thick (such as a single layer > 2mm) will cause uneven drying inside and outside, prolong the actual drying time, and even blistering and cracking.
4. Material ratio (two-component)
- The wrong ratio of the main agent to the curing agent will destroy the reaction balance, resulting in incomplete curing or abnormal time.
5. Substrate conditions
- Porous or highly absorbent foundations (such as concrete) may absorb moisture/solvents in the coating and delay the curing of single components.
6. Ventilation conditions
- Good ventilation helps to volatilize moisture or solvents and accelerate curing; a closed environment may prolong the curing time.
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III. Construction recommendations
1. Strictly control the ratio, coating thickness and construction environment according to the product instructions.
2. In low temperature or high humidity environment, heating, dehumidification or extended curing time can be adopted.
3. Avoid contact with water or weight before complete curing to prevent damage to the coating.
By properly controlling the above factors, construction efficiency can be optimized and waterproof performance can be ensured.