Plastering TechniquesWhoever said plastering is easy is not being truthful. Plaster finishing a wall is not an easy job. There's more to plastering that just a trowel, float and your finishing compound. Professional plasterers have said that more often than not, a remarkable percentage of their work comes from botched jobs done by over-enthusiastic DIY-er. Plastering finishing is do-able as some people are really "gifted" with their eye/hand coordination. Now for those well-meaning klutz, it will be more cost efficient and certainly less stressful if you'll just pick up the phone and call for a professional plasterer.
The art of plastering has been observed in structures as ancient as the Pyramids of Egypt and the Greek and Roman ruins. Great cathedrals and palaces of the past centuries, the Gothic period in particular, had superb plastering that are still evident today. The plastering materials that they used could have been lime plaster.
Two types of plastering materials today
There are two types of plastering materials used today; cement-based and gypsum-based plastering. For the most part applying gypsum based cement on gypsum board is the easier route in skimming. Skimming is the final plastering done on a wall. Gypsum-based plastering are used in interior plastering because of its more susceptible to moisture. Cement-based plastering could both be applied indoors and outdoors.
Over the years different plastering techniques have been innovated. The old and tested method of plastering are still used today but newer methods in terms of new materials or additives are now gaining popularity especially in interior plaster finishing.
Stucco plaster finishing is still widely used in exterior treatment of walls. Stucco is actually a general term applied to all types of exterior plastering whether it be lime or cement. There are four composites under stucco and they are:
- Common stucco - It is a mixture of one part cement (or hydraulic lime) and 3 parts sand. It's plain finishing of an exterior wall.
- Rough stucco - It is a type of exterior finishing imitating stonework. The effect is done by the use of a hand float covered with rough felt. Some plasterers prefer to use brushes with stiff bristles for the effect.
- Trowelled stucco - This has a very smooth finish achieved by the use of a hand float. The finishing coat is 3 parts sand to 2 parts cement.
- Bastard stucco - This surface is almost like the common finish but this is laid instead on two coats with a skimming float, cleaned then trowelled.
Roughcast plaster finishing is a type of coarse finishing where cement, pebbles, shells, and sand are mixed together with water and then thrown at the wall with a trowel. The idea is to cover the wall evenly with the mixture for a rough but finished look. This finishing used to be a popular exterior finishing at the turn of the 20th century. It is now more commonly used in country homes.
Modern stucco is exterior cement plastering. It is a mixture of cement, lime, sand and water in a proportion that is most suitable for the plasterer. Additives are put into the mixture for more flexibility. There are also synthetic stuccos that are out in the market today. They are called by many names and types but they are all basically cement-based stucco plastering. There are three essential coats for cement-based plastering: the scratch coat; the brown coat and the final coat. The scratch coat is the foundation coat and needs to be scratched for the second finer coat to adhere. The brown coat is finer but the third and final coat still needs to be applied for that smooth and finished look. The final coat can be colour coat where the sand and cement are mixed with a coloured component or the final coat could be finished off with an application of paint or any acrylic-based finish.
Interior plastering is different from exterior plastering. There are two types of plastering used for the interior: drywall and plastering. Drywall is a form of sheet rock that is somewhat greenish in colour. It is actually a method of constructing interior walls by making use of gypsum boards. The drywall boards are 4 feet by 8 feet s and are screwed to the wall studs to form the wall. In between the edges of drywall sheets are seams. These seams are covered with mesh tape after which the screws and the seams are covered with drywall plaster to conceal them for a finished look. The drywall can either be painted on or wallpapered for the final finishing touch.
Veneer plastering is different. Instead of covering just the seams, the whole wall is plastered with a thin very workable compound. The surface could be ply board, drywall or even cement. The interior wall material does not really matter as the veneer plastering will cover it anyway. Veneer plastering can be smooth, textured or sponged. The finishing depends on the owner's preference or the architect's design.
There are different methods of veneer plastering. The most notable are the varied faux finishes that are available in depots today. Gaining more popularity is the Venetian plastering where manufacturers claim that your walls will have that authentic "old world" ambiance. Venetian plastering is a type of textured plastering that has the colour ingrained in the plaster itself. It is more commonly known as "aged" plaster.
Plastering is not an easy task but if you have the tenacity to take up the art, then you'd be able to do small areas in no time at all. Tip: practice.
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