Floats are used during the plastering process to make sure that every part of the wall is as flat and smooth as possible – known as floating.For more information see How to float plaster?
Floating plastered ceilings
A float is often used to make sure a ceiling is as flat as possible. If plastering a whole room, do the ceiling before the walls in case of any drips.Ceiling plaster should be thinner than on the walls – about 2mm for the first coat, and 1.5mm for the second. A damp sponge float will help stop the plaster drying out too quickly, which tends to be the biggest problem with ceilings.
Floating render
The plaster on external walls is called render, also known as stucco. Render may be floated in order to:
Magnesium floats are designed to smooth over and flatten newly laid concrete surfaces. For more information see: How to float concrete.
Finishing pointed walls
Sponge floats can be used to achieve a good finish on outside walls that have been freshly pointed (where gaps between bricks or stones have been filled with mortar). You can use them to add mortar to any remaining crevices, smooth over ridges and remove excess material.
Grouting tiles
Rubber and sponge floats are a popular choice for grouting wall and floor tiles. For more information see: How to grout tiles with a float?
Keying plastered walls
You can use a use a wooden float with screws or nails driven into it, called a devil float, to key the wall before applying the final coat.Keying involves making shallow scratches all over the wall to create a good gripping surface for the top layer of plaster. For more information see How to key a wall with a float?