Painting the interior and exterior surfaces of a building is an essential step not only to enhance its visual appeal but also to increase its value and protect it from natural elements. Moreover, painting helps conceal any repaired damages, giving the building a fresh and well-maintained look. This article provides a detailed procedure for painting plastered surfaces, including preparation, application, and special considerations when using cement paints.
Preparation of the Plastered Surface
Before starting any painting work, thorough preparation of the plastered surface is crucial. The surface must be cleaned adequately to remove dust, dirt, rust, grease, mortar droppings, smoke splashes, and any other contaminants. Proper cleaning ensures that the paint adheres well and lasts longer.
In addition to surface cleaning, the rooms and the entire building should be swept out and cleared of debris. An inspection by an engineer or qualified supervisor is often required to approve the prepared surface before painting begins.
Painting should never be conducted during adverse weather conditions such as hail storms or dust storms, especially when working on external surfaces. These conditions can negatively affect the paint application and drying process.
Application of Paint: Paints, Oils, and Varnishers
To achieve a smooth and uniform finish, paint must be stirred thoroughly before use and continuously stirred during application to maintain consistent texture. Paint is typically poured into smaller, manageable containers to facilitate this process.
The preferred method of applying paint is by brushing using a technique known as “crossing and laying off.” This involves brushing the surface firmly in one direction, then in the opposite direction multiple times, and finally lightly brushing at a right angle to the initial strokes. This method ensures even distribution of paint without visible brush marks, with the entire process constituting one coat.
In some cases, painting by spraying is preferred. Spray machines can be either high-pressure or low-pressure, depending on the work’s nature and location. Skilled workers add appropriate thinners to the paint to achieve the desired consistency for spraying. Spraying should be carried out only under dry weather conditions to ensure optimal adhesion.
Each coat of paint must be allowed to dry completely before applying the next. Except for the final coat, each layer should be lightly rubbed down using sandpaper or fine pumice stone to create a smooth surface. All dust must be removed before the next coat is applied. It is important that the final finish has no brush marks, paint puddles, or clogged areas, especially in corners and moldings.
Painting with Cement Paints
Cement paints require special handling and application techniques. Because cement paint sets quickly, it should be mixed only in small quantities that can be used within an hour.
Preparation of Cement Paint Mix
Mixing cement paint involves two stages. Initially, two parts of cement paint are mixed with one part water and stirred thoroughly, then allowed to rest for five minutes. After this, an additional one part of water is added and stirred again until a workable and uniform consistency is achieved.
Since cement paint is hygroscopic, exposure to air causes it to set rapidly. Therefore, lids of cement paint drums must be kept tightly closed when not in use to maintain the paint’s usability.
Application of Cement Paint
Cement paint should be applied to clean, wetted surfaces using a brush or spraying machine. The paint solution must be stirred regularly during application to maintain consistency.
To prevent premature drying and cracking, the paint should be applied on the shaded side of the building, avoiding direct sunlight. After completing a day’s work, the painted surface should be watered to aid curing.
The second coat of cement paint can be applied only after the first coat has set for at least 24 hours. Importantly, the surface of the previous coat should not be wetted before applying subsequent coats.
For new buildings, three or more coats of cement paint are recommended to achieve a uniform and durable finish. For maintenance or repainting of old buildings, one or more coats can be applied depending on the required coverage and uniformity.
Conclusion
Proper painting of plastered surfaces is a meticulous process that requires careful surface preparation, skilled application, and adherence to drying and curing guidelines. Whether using traditional paints or cement-based paints, following the correct procedure ensures a high-quality finish that enhances the building’s aesthetics, longevity, and protection against environmental damage.