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How to paint on new plaster


At Mid Cornwall Decorators, our experts emphasize the importance of ensuring that new plaster and plasterboard are fully dry before painting. When working with new plaster, it is essential to apply a dilute first coat, known as a mist coat, to allow the paint to penetrate and bind to the surface. After the mist coat has been applied, we recommend following up with two full, undiluted coats to complete the job.

To determine if your diluted paint is ready for application, check the consistency. It should be similar to single cream and should not sit on the surface. If the paint is absorbed immediately by the plaster, it is at the proper consistency. If it sits on the surface, the ratio is too thick and you should add more water and mix it with a paddle whisk attached to a cordless drill. Remember to take your time and enjoy the process as you work. Paddle whisks can be purchased at most hardware stores for around £5.

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Make sure the plaster is dry

It is essential to allow new plaster sufficient time to dry before painting to achieve an even result. The drying time will depend on the room temperature, ventilation, and the thickness of the plaster. As a general rule, you should wait approximately four weeks for every 5mm of plaster depth, taking into account seasonal variations in temperature. Before beginning to paint, check that the freshly plastered surface is uniformly colored and lacks dark patches, which may indicate that the plaster has not fully dried. Additionally, newly constructed or renovated rooms may take longer to settle, so it is important to be patient and wait for any cracks to appear before starting the painting process. This will allow you to address any imperfections and ensure a smooth finish.

Make a 
mist coat

Fresh plaster is highly porous and will absorb moisture easily, which is why it is necessary to dilute the first layer of paint, also known as a mist coat. To create a mist coat, mix a cheaper emulsion paint in a similar color to your top coat with water. The ratios will depend on the specific paint you are using, so be sure to check the manufacturer's recommendations on the tin. At Mid Cornwall Decorators, we recommend a ratio of approximately three parts paint to one part water for the mist coat. Stir the mixture until you have an even, milky consistency with no water sitting on top of the paint. It is essential to use a non-vinyl, water-based paint to allow the plaster to breathe and release any excess moisture.


Allow the mist 
coat to dry 

The drying time for a mist coat typically ranges from 24 hours, but this can vary depending on the conditions in the room. After the mist coat has dried, you may choose to apply a second coat for a more solid appearance on walls and ceilings. Once the desired number of coats have been applied, you can proceed with the top coats.

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