How to Prepare of Newly Constructed and Plastered Walls for Painting? - HOMESLIBRO - Blogs on Home Related Solutions

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How to Prepare of Newly Constructed and Plastered Walls for Painting?


General Preparation

Let us assume that the wall has been built and cured. After the wall has dried and matured for a few months, we first apply a coat of cement primer (white). Irregularities of the surfaces can be rectified by applying putty before painting is started. For example, in ordinary house construction, we can use plaster of Paris as putty. For superior work as in showrooms, special copolymer emulsion putty which is suitable for exterior and interior and also contains the primer coat is also available in the market. They are, however, costly. It is more convenient to first apply white primer on cement-plastered walls before applying putty.


The white background obtained after applying white primer shows up the irregularities and then, the putty can be applied more effectively. This procedure also reduces the amount of putty required. The putty coat is rubbed with sandpaper to smoothen the surface. After that, one more coat of primer can be applied, and it is allowed to dry for 10 to 12 hours before applying the chosen paint as the undercoat. The following points are important in this case:


1. Oil and acrylic paints, and distempers do not fare well if there is alkalinity in the surface to be plastered or if the wall has been previously whitewashed with lime. Hence, it is essential to apply alkali-resistant primer on these whitewashed surfaces before applying the prescribed paints.


2. While painting the exterior walls, all molds, algae, moss, etc. should be removed


3. When efflorescence is seen in the brick wall, water should not be used to wash out the efflorescence. If water is used, the salt may be absorbed back into the pores and precipitated again on the outside when it dries out. Hence, the deposit should be brushed and cleaned in the dry state itself. We may use acid etching


Procedure for Painting New Buildings

As we have seen in the last section, fresh concrete, cement, and lime plaster have moisture in them. They are highly alkaline. Hence, it is preferable to paint these surfaces only after 3 to 6 months when the plaster work is completed. Even then for new works, it is considered better to use primer paint to start with. These primers are special paints for new works.

In addition, there may be pores to be filled. Hence, we use a filling-in compound or a filler coat. Thus, in all new painting works, we have the following five operations:

1.  Cleaning the surface by proper sandpapering (The sandpaper we use for different surfaces is different.)

2.  Application of primer coat

3.  Filling the small dents with a filler coat

4.  Application of the first undercoat of the paint

5.  Application of finishing coats

Thus, in addition to the main paint, we must use the primer coat and the filler coat in the new works.

 

Primer Coats

The names of some of the primer coat paints used for building works are given in Table


Procedure for Painting New Buildings


Note: The covering capacity of these primers is about 18 to 20 m2/liter per coat

 

Filler Coats

As discussed above, the third operation in painting is to fill the small dents (that are on the object) with filler coats. For example, we usually use wall putty on the walls. When using enamel paint, we generally use a paste filler coat.


The wall putty can be prepared by mixing powdered chalk (whitening) with 5% to 10% enamel paint (commercial grade) and 25% to 30% water. These are mixed well to form a homogeneous mixture.




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