Applying paint to new plaster requires a specific approach to ensure proper adhesion and a lasting finish. The key is to let the plaster fully dry and then apply a "mist coat" before any regular paint. Here's a step-by-step guide:
1. Ensure the Plaster is Completely Dry
- Wait: This is the most crucial step. New plaster needs adequate time to dry completely. Drying time varies depending on factors like humidity and ventilation, but generally, allow at least a week, often longer.
- Check for Uniform Color: The plaster should be a consistent, light color with no dark patches indicating dampness.
2. Prepare Your Materials
You'll need:
- Emulsion Paint: Choose a good quality emulsion paint for the mist coat and your desired topcoat color. Matte or matte finish paint are typically recommended for newly plastered walls.
- Water: For thinning the mist coat.
- Paintbrushes and Rollers: Choose appropriate sizes for the area you're painting.
- Paint Tray: For holding the paint.
- Mixing Bucket: For creating the mist coat.
- Dust Sheets/Drop Cloths: To protect your floors and furniture.
- Painter's Tape: To mask off edges and trim.
3. Mix the Mist Coat
The mist coat is a crucial primer for new plaster. It's essentially watered-down emulsion paint that helps seal the porous surface and allows the topcoat to adhere properly.
- Ratio: A typical ratio is 50% emulsion paint and 50% water. However, some may recommend a 60/40 paint/water ratio, or even 70/30, depending on the paint consistency and plaster porosity. Start with 50/50 and adjust as needed. The mixture should be milky and easily spreadable.
- Mix Thoroughly: Use a mixing stick to ensure the paint and water are fully combined, creating a consistent mixture.
4. Apply the Mist Coat
- Apply Liberally: Apply the mist coat evenly to the entire plastered surface using a roller or brush. Don't be afraid to apply it generously, as the plaster will absorb a lot of the mixture.
- Avoid Runs and Drips: While applying liberally, watch for runs or drips and smooth them out immediately.
- Allow to Dry Completely: Let the mist coat dry completely according to the paint manufacturer's instructions (typically 2-4 hours, but check the can). The wall should look evenly sealed and less porous.
5. Apply the Topcoat(s)
- Lightly Sand (Optional): After the mist coat is dry, lightly sand the surface with fine-grit sandpaper to remove any imperfections or nibs. Wipe away any dust with a damp cloth.
- Apply Topcoat(s): Apply one or two coats of your chosen emulsion paint color, following the manufacturer's instructions for drying time between coats. Use a roller for large areas and a brush for edges and trim.
- Even Coverage: Ensure even coverage with each coat for a smooth, professional finish.
Key Considerations:
- Ventilation: Ensure the room is well-ventilated during painting and drying.
- Paint Quality: Using a good quality paint will result in a better and longer-lasting finish.
- Drying Times: Always adhere to the paint manufacturer's recommended drying times.
- Testing: If unsure about the plaster's dryness, you can tape a small square of plastic wrap to the wall for 24 hours. If moisture collects underneath the plastic, the plaster is not yet dry enough to paint.
