Plastering, Pointing & Painting

Introduction to Plastering, Pointing and Painting. Objective, various types, ideal characteristics, defects are briefly covered and presented.

1. PLASTERING, POINTING & PAINTING - Mohammad Aquib B.E. (Civil Engineering) R.T.M. Nagpur University, Nagpur Diploma in Civil Engineering M.S.B.T.E., Mumbai

2. PLASTERING: “Process of covering rough surfaces of walls, columns, ceilings and other building components with thin coat of plastic mortars to form a smooth durable surface.”

3. OBJECTIVES OF PLASTERING 1 . To provide an even , smooth, regular, clean and durable finished surface . 2. To preserve and protect the surfaces from atmospheric influences 4. To cover the defective workmanship, porous materials and the joints formed in the masonry works. 5. To provide a satisfactory base by applying white washing, painting, distempering . 6. In internal plastering, the basic objective is to protect from dust.

4. 1. Surface Preparation All masonry joints should be cleaned. All unevenness should be removed. Mortar drop and dust is removed with wire brushes. The surface is washed and kept wet. Application of Cement Slurry. 3. Application of Mortar 4. Finishing 5. Curing PROCEDURE OF PLASTERING

5. DEFECTS IN PLASTER 1. Blistering of plastered surface F ormation of small patches of plaster swelling out beyond plaster surface C ause due to late slaking of lime particles in plaster 2. Cracking F ormation of cracks or fissures in plaster Caused due to- imperfect preparation of background structural defects in building 3. Efflorescence Presence of whitish crystalline substance on the surface Caused due to presence of salts in plaster-making substance and building materials

6. 4. Flaking Formation of very loose mass of plastered surface Caused due to poor bond between successive coats 5. Peeling C omplete dislocation of some portion of plastered surface, resulting information of patch 6. Rust stains F ormed when plaster is applied on metal laths 7. Uneven surface Happen due to poor workmanship Continue…..

7. POINTING “Basically, finishing of mortar joints in masonry.”

8. PROCEDURE OF POINTING “Pointing consists of raking the joints to a depth of 10-20 mm and filling it with better quality mortar in desired shape.” Image courtesy Handyman

9. TYPES OF POINTING 1. Flash pointing F ormed by pressing mortar in raked joint and by finishing off flush with edge of masonry units. E dges are neatly trimmed with trowel and straight edge & extensively used. 2. Recessed pointing Pointing is done by pressing mortar back from edges by 5mm or more. Face of pointing kept vertical. 3. Rubbed, keyed or grooved pointing Modification of flush pointing Groove at its mid height Gives better appearance Flash Pointing Grooved Pointing Recessed Pointing

10. Continue…. 4. B eaded pointing Formed by steel or ironed with a concave edge Gives good appearance Liable to damage easily 5 . Struck pointing Modification of flush pointing Face of pointing is inclined, upper edge pressed inside the face by 10 mm. Drains water quickly 6. Tuck pointing Formed by pressing mortar in racked Joint, finishing flush with face. Groove or narrow channel (5 mm width, 3 mm depth) is cut in the centre w hile pressed mortar is green

11. Continue…. 7. V- Pointing Forming V-groove in flush-finishing face 8. Weathered pointing Forming V-shaped projection

12. PAINTS “ The paints are coating of fluid material and they are a pplied over the surface of timber and metals .” Paint is a liquid composition after application it is c onvert in to a solid film. COMPOSITION OF PAINT 1 . Pigment - To provide colour , hiding and control gloss. 2. Resin – T he binder to hold the pigment particles together and provide adhesion to the surface painted. 3. Solvent – To act as a carrier for the pigments and resin –the solvent may be organic Or Inorganic (such as Mineral , Chemicals or water). 4. Additives – To enhance certain properties such as ease of brushing, M ould resistance, scuff resistance, drying and sag resistance.

13. CHARACTERISTICS OF AN IDEAL PAINT: 1. Form a thin film of uniform nature 2. W ithstand the adverse environmental conditions 3. E asy application on surface 4. A ttractive and pleasuring appearance. 5. No visible cracks after drying 6. E lastic in nature (must be able to withstand change in temperature). 7. R esistance to corrosion 8 . G ood spreading or covering power 9. No visible marks of roller or brush (in the form of bubbles or stripes). 10. N o visible joints

14. TYPES OF PAINTS Paints are categorized in to seven groups: 1. Oil paints 2. Synthetic paints 3. Emulsion paints 4. Cellulose paints 5. Varnishes 6. Water paints (distemper) 7. Special paints

15. PAINTING DEFECTS 1. BLEEDING: Its an disruption and staining of the painted surface by chemical action. It happens when an incorrect paint is applied over another such as bituminous one. The remedy is to remove the old paint and renew with a like one . 2. BLISTERING : It is a common failure caused by poor adhesion or by moisture pushing off the paint. It is prevented by having a dry background , proper priming and removal of very resinous knots .

16. PAINTING DEFECTS (Continue…) 3 . BLOOMING: It is the mistiness which can appear on varnished or highly glossed surfaces. Due to the presence of moisture, draughts or frost during application or condensation on newly painted areas. Remedy is to repaint. 4. BRUSH MARKS: These may be due to the paint being too stiff, by poor workmanship or by brushing over paint which has partially set . They are removed by rubbing down with waterproof abrasive followed by repainting .

17. PAINTING DEFECTS (Continue…) 5 . CHALKING: It is the powdering of a paint film usually on exposed outside surfaces. It is a sign that repainting is necessary and may be due to poor quality paint . 6. CISSING 7. FLAKING F ailure of paint to adhere properly to a surface .   The detachment of  paint  film (the breaking of  coating)

18. Thank you!!!