You should sand joint compound once it is thoroughly dry, typically after drying for 4 to 8 hours, depending on environmental conditions.
Determining Readiness for Sanding
Knowing when joint compound is truly ready for sanding is critical for a smooth finish. While a general timeframe of 4-8 hours is often cited, this can vary significantly based on:
- Temperature: Warmer temperatures speed up drying.
- Humidity: High humidity slows down the drying process considerably.
- Thickness of application: Thicker coats take longer to dry.
- Ventilation: Good airflow helps accelerate drying.
The Sandpaper Test
The most reliable way to check if joint compound is ready for sanding is by performing a simple test mentioned in the reference:
- Run a piece of sandpaper lightly over a section of the dried joint compound.
- Observe the result:
- If the sandpaper creates fine dust, the compound is dry and ready.
- According to the reference, if the surface balls up and is soft to the touch, it is not ready to be sanded. This indicates there is still moisture within the compound.
Key takeaway: Even if the recommended drying time has passed, always perform the sandpaper test. Sanding compound that is not fully dry can lead to a messy, uneven finish and gum up your sandpaper.
Best Practices for Sanding Joint Compound
- Ensure the area is well-ventilated.
- Wear appropriate safety gear, including a dust mask or respirator and safety glasses.
- Use the correct grit sandpaper for the job (typically starting with 120 or 150 grit).
Remember, patience during the drying process is key to achieving a professional-looking result when finishing drywall.
