• Preparation of the plaster should be in the right proportion.
• The applying consistency of the application must be right.
• The plaster durability should be high and challenging in nature.
• The ingredients of the application has to be economical.

What is External Plastering?

External plastering refers to the plastering of exterior walls covering uneven surfaces with a plastic material called plaster. The most common types of application are gypsum, lime, or cement mixed with water and sand. The recommended wall plastering thickness ranges from 15 mm to 25 mm. It may be 15 mm, 18 mm, 20 mm, and 25 mm. The 15 mm thickness is a single coat, whereas the 18 mm, 20 mm, and 25 mm is a double coat. The five main types of plastering on walls and their ingredients are explained.

Special plaster: The special applications are made with unique mixes that are required for decorating the surface of walls or for particular purposes like waterproofing, restricting shrinkage, etc.,

Waterproof plaster: The waterproof application's purpose is to protect the Masonry walls from moisture and dampness. This plaster is made of cement and sand mix in the ratio of 1:2. Pulverized alum and soft soap are added, which reacts chemically and seals the pores on the walls.

Lime plaster: The lime plaster is made by mixing equal volumes of lime and sand. In this Lime plastering method, the boiled solution of bael fruit, jugal, and roped hemp is added to the mortar to prevent the appearance of cracks on the surface.

Stucco plaster: This type of plastering is used for the decorative feature, the cement and sand mix. The application has three coatings with a thickness of 25 mm. The first scratch coat is 10 mm thick, the second brown coat is also 10 mm thick, and the finishing white coat is 4-6 mm thick. The mix ratio for the first and second coating is 1 : 3 cement and sand with 10% hydrated lime. The mix ratio for the finishing coat is 1: 2 cement sand mortar.

Composite plaster: The hybrid application is made by mixing the cement, lime, pozzolana or surki, and sand in different ratios. Also, the thickness and the number of coatings vary depending on the application area.

How to plaster the wall?

Working with the plaster is a highly technical process that the professionals or plasterers can neatly do. The dressing is manufactured as a dry powder, made into a workable paste by mixing with water before application.

1. Prepare the work surface and materials by cleaning the working tools and the walls to be free from oily dirt, dust, and other debris.
2. Make sure you lay the drop cloth around the working surface to avoid messy clean-up after the work is done.
3. Brush or roll the PVA glue in the mix ratio of 1 part glue to 4 parts of water. This helps the new plaster stick to the wall and prevent moisture escape inside the house.
4. Now, add the plaster mix to the water and not the other way around. The plunger, stirring rod, or electric drill is used for mixing it easily.
5. Keep stirring the plaster continuously to thicken it and ready to use consistency.
6. To apply the first coat, heap some fresh plaster, place it in the center of the trowel and smear it onto the wall right from the bottom corner. Then smooth the first coat by applying a consistent pressure for a uniform thickness finish.
7. Scoring the first coat using deviling float or notched trowel creates shallow grooves that help the second coat adhere better. 8. Apply the second and the final coat in the same way and make sure there are no gaps or seams.
8. For an even finish, workout the lumps, holes, lines, and inconsistencies in thickness for a smooth plastering.
9. Finally, allow the plaster to set, which depends on the various conditions like temperature, the composition of the application, and moisture in the air. It usually takes 2-5 days to harden fully.

Note that the wall should be arid before applying paint, wallpaper, or any other decorative features.