Newly plastered walls provide a smooth, blank canvas for creative decorating. However, without proper preparation, paint may not adhere correctly leading to an uneven finish or flaking. This article explains crucial steps like allowing adequate drying time, applying a mist coat, and sanding between topcoats.
Letting plaster fully dry before painting is critical because paint won’t adhere well to damp surfaces which can cause flaking. Sealing the plaster with a mist coat is also very important because new plaster is highly porous. If left unsealed, it can absorb paint unevenly leading to a patchy finish. The mist coat acts as a primer that prepares the plaster for painting.
Follow these tips for professional-looking painted plaster guaranteed to withstand the test of time.
Step 1: Let the Plaster Dry
Fresh plaster requires ample drying time before painting can begin. Exact timing varies based on plaster type, thickness, and ambient conditions. Expect at least a few days, up to several weeks. Avoid speeding drying with heaters or dehumidifiers as this risks cracking the plaster. Test dryness by checking for a consistent light color throughout with no dark spots remaining. The plaster is ready for painting when fully dry.
Step 2: Prepare the Surface
Proper prep prevents problems down the line. Begin by sanding the plaster to smooth any imperfections for an optimal painting surface. Protect floors, furniture, and fixtures from splatter using drop cloths and masking tape. Ventilate the workspace if using strong-smelling paints.
Step 3: Apply the Mist Coat
The mist coat is a vital first step when painting new plaster. This thinned emulsion acts as a primer that seals porous plaster to prevent uneven paint absorption.
Why It’s Needed
Untreated new plaster readily soaks up paint solvent, causing the paint to dry too quickly before adhering correctly. The mist coat resolves this issue. It allows paint to bond seamlessly to the plaster.
Mixing the Mist Coat
- Choose a quality emulsion paint
- Pour required amount into a bucket
- In a separate container, measure water at a 3:1 ratio (paint:water)
- Slowly add water, stirring continuously, until milk-like consistency is reached
- Adjust ratio as needed based on paint thickness
- Mix until fully blended with no lumps
For cost savings, use a more affordable emulsion for the mist coat. The key is achieving a balance – thin enough to penetrate plaster yet thick enough to prime it.
Step 4: Apply the Mist Coat
Use a roller for large areas, switching to a brush for edges and intricate sections. Keep the roller well-coated but not overloaded. Use smooth, consistent motions, working top-down. For right-handers, paint left-to-right and vice-versa for best results.
Step 5: Sand Between Coats
Lightly sand the surface after each coat dries. This removes any plaster nibs or splatter and creates an ultra-smooth finish. Use fine grit sandpaper and clean dust before adding the next coat.
Step 6: Finish with Topcoats
Once the mist coat has dried fully (typically 24 hours), apply your topcoats. Two or more coats may be needed depending on the desired finish and paint quality. Use a V motion for even coverage and allow ample drying time between coats.
FAQ’s
How long does new plaster need to dry before painting?
New plaster can take anywhere from a few days to several weeks to dry completely depending on the plaster thickness, type, and ambient conditions. It’s important to allow adequate drying time to prevent paint adhesion issues.
Why is a mist coat needed when painting new plaster?
New plaster is porous and tends to absorb paint unevenly. A mist coat acts as a primer that seals the plaster and provides an even base for painting.
What is the ratio for mixing a mist coat?
A typical mist coat ratio is 3 parts emulsion paint to 1 part water. However, the exact ratio may need adjusting based on the consistency of the paint. Aim for a milk-like consistency.
Should you sand between coats when painting plaster?
Yes, lightly sanding between coats helps achieve a smooth finish by removing any plaster nibs or splatter. Use fine grit sandpaper and clean dust before adding the next coat.
How many topcoats are needed when painting new plaster?
The number of topcoats needed depends on the desired finish and paint quality. Typically 2 or more coats are required for best results. Allow ample drying time between coats.
Key Takeaways
- Wait for plaster to dry completely before painting
- Prepare surface by sanding and protecting flooring
- Apply a mist coat first to seal porous plaster
- Lightly sand between all coats for a smooth finish
- Allow proper drying time between coats
- Use quality brushes and emulsion for best results
Achieving a flawless painted finish on new plaster requires patience and technique. By following the steps in this guide, beginning with allowing adequate drying time and using a mist coat primer, beautiful, durable results are attainable. Proper preparation and finishing with smooth topcoats complete the process. With this approach, newly plastered walls will not just look stunning but will stand the test of time.