A box fan blowing on drywall patching compound can potentially decrease the cure time, but the actual effect may vary depending on several factors.
Drywall patching compounds, such as joint compound or spackle, typically cure by a process of evaporation. When the compound is applied to the wall, the water or other solvents in the mixture begin to evaporate, leaving behind a hardened surface.
A box fan blowing on the patching compound can speed up the evaporation process by increasing air circulation and promoting the movement of air across the surface. This increased airflow can help carry away moisture from the compound, thus accelerating the drying time.
However, there are some important considerations:
Humidity: If the ambient humidity is already low, the fan's impact on curing time might be more significant. In areas with high humidity, the fan may not have as much of an effect, as the surrounding air is already saturated with moisture.
Thickness of Patching Compound: The thickness of the applied patching compound will also influence the drying time. Thicker layers will take longer to cure than thinner ones, and the fan's effect may be more noticeable with thicker layers.
Temperature: Higher temperatures generally accelerate the drying process. If the room is already warm, the fan might have a more substantial effect on reducing cure time.
Manufacturer Recommendations: It's essential to follow the manufacturer's recommendations regarding drying time, as excessive air circulation or temperature changes could negatively affect the quality of the patching job.
Cracking and Shrinkage: Rapid drying, especially in hot and dry conditions, can increase the likelihood of cracking and shrinkage in the patching compound, which may lead to additional repairs.
If you decide to use a fan, it's best to start with a moderate setting and observe how it affects the drying process. Too much airflow can cause other issues, such as dust settling into the compound or uneven drying.
Always refer to the specific instructions on the patching compound product label or consult with a professional to ensure you are using the best approach for your particular situation.