The profession of a plasterer involves a tradesman who works with plaster, this consists of forming layers of plaster on an interior or exterior wall or someone who plasters decorative mouldings or either ceilings or walls. The art of plastering has been used in building construction for centuries.
Nowadays plastering walls and ceilings require few tools and less materials are needed. The materials involved within the workman are laths, lath nails, lime, sand, hair, plaster of Paris and a variety of cements, amongst other materials to form colouring washes.
Depending on the type of plastering you want different ingredients are used.
For fine plasterers sand work, special sands are used such as, silver sand or fine foundry; these ingredients are used when the customer wants a light colour or a fine texture. Specifically in medical centres one part barium is added to two parts cement and five of sand, these are used where the walls need to block x-rays.
When you decide to render or coat a concrete surface a splash coat of one part cement to one of san in liquid form is either thrown with a trowel or sprayed on the surface. This is needed if you want to provide a better key for the render, even better; it prevents the porous concrete from sucking the water from it. Taking into account external work – Portland cement has proven to be the most effective concrete due to its sturdiness, durability and weather resistance. If a plasterers job involves plastering a wall such as a squash wall which needs to be particularly strong and needs to prevent against cracking, sizing is mixed with the plaster before the application, this creates flexibility and surface bond strength making the wall suitable for the activity.
The first coat of render is from ½ to ¾ inches this, and is mixed, dependant on the surface to be covered in the proportions of from one part of cement to two of sand to one part to six of sand. Half a shovel of lime is usual added to the mixture to make it pliable. After dampening the surface to be coated, two horizontal bands of render called screed are applied, one at around head height and the other just above floor level, these are then marked for vertical/ horizontal alignment, finished, then allowed to partially dry. In a process similar to laying concrete, the wall is then rendered to a slightly higher level than the screeds and using a straight edge, the plasterer used the screeds as guides removing the excess render and leaving a rough flat surface. The render is then finished with a float to fill or remove larger imperfections. For some applications where a stronger key is required the surface is scored by later use of a float with nails protruding from the base. If the render is to be the finished surface then a float with a sponge attached to the base is then used on the wall until the surface is blemish free.
Due to many walls being uneven, some may run out of plumb with means that there will be a large variation in render thickness, to solve this problem, a thin ‘scratch’ render coat is first applied then a second coat will be added as a finish as described above. Once you have left that for a day the render would have dried out, but just before you add the final plaster coat a trowel is used to scrape together any loose sand grains that maybe on the surface, this has to be done otherwise it will spoil the plaster finish.
When you are ready to add the finishing or setting plaster coat, which is about 3/16 inches is worked with a hand trowel on the surface on the rendering, but you have to make sure that it is well wetted. The plaster is applied in two coats because it slows down the drying process of the second coat. Afterwards, once it has dried you will still need to go back to the wall, wet it and work at it for some time so it can produce a thin watery layer which gives the wall a ‘polish’ effect. This usually takes two or three passes to achieve the finished look.
Nowadays plastering walls and ceilings require few tools and less materials are needed. The materials involved within the workman are laths, lath nails, lime, sand, hair, plaster of Paris and a variety of cements, amongst other materials to form colouring washes.
Depending on the type of plastering you want different ingredients are used.
For fine plasterers sand work, special sands are used such as, silver sand or fine foundry; these ingredients are used when the customer wants a light colour or a fine texture. Specifically in medical centres one part barium is added to two parts cement and five of sand, these are used where the walls need to block x-rays.
When you decide to render or coat a concrete surface a splash coat of one part cement to one of san in liquid form is either thrown with a trowel or sprayed on the surface. This is needed if you want to provide a better key for the render, even better; it prevents the porous concrete from sucking the water from it. Taking into account external work – Portland cement has proven to be the most effective concrete due to its sturdiness, durability and weather resistance. If a plasterers job involves plastering a wall such as a squash wall which needs to be particularly strong and needs to prevent against cracking, sizing is mixed with the plaster before the application, this creates flexibility and surface bond strength making the wall suitable for the activity.
The first coat of render is from ½ to ¾ inches this, and is mixed, dependant on the surface to be covered in the proportions of from one part of cement to two of sand to one part to six of sand. Half a shovel of lime is usual added to the mixture to make it pliable. After dampening the surface to be coated, two horizontal bands of render called screed are applied, one at around head height and the other just above floor level, these are then marked for vertical/ horizontal alignment, finished, then allowed to partially dry. In a process similar to laying concrete, the wall is then rendered to a slightly higher level than the screeds and using a straight edge, the plasterer used the screeds as guides removing the excess render and leaving a rough flat surface. The render is then finished with a float to fill or remove larger imperfections. For some applications where a stronger key is required the surface is scored by later use of a float with nails protruding from the base. If the render is to be the finished surface then a float with a sponge attached to the base is then used on the wall until the surface is blemish free.
Due to many walls being uneven, some may run out of plumb with means that there will be a large variation in render thickness, to solve this problem, a thin ‘scratch’ render coat is first applied then a second coat will be added as a finish as described above. Once you have left that for a day the render would have dried out, but just before you add the final plaster coat a trowel is used to scrape together any loose sand grains that maybe on the surface, this has to be done otherwise it will spoil the plaster finish.
When you are ready to add the finishing or setting plaster coat, which is about 3/16 inches is worked with a hand trowel on the surface on the rendering, but you have to make sure that it is well wetted. The plaster is applied in two coats because it slows down the drying process of the second coat. Afterwards, once it has dried you will still need to go back to the wall, wet it and work at it for some time so it can produce a thin watery layer which gives the wall a ‘polish’ effect. This usually takes two or three passes to achieve the finished look.