What sandpaper grit sizes are available?
What sandpaper grit sizes are available? |
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A sandpaper’s grit size means the size of the particles that are embedded in the sandpaper. The particles are measured in micrometers. A micrometer, also known as micron, is one millionth of a metre, or one thousandth of a millimetre. | |||||||||||||||||||||
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Grit size can be measured in terms of two standards, which are the Coated Abrasive Manufacturers Institute (CAMI) and the Federation of European Producers of Abrasives (FEPA). Both standards separate grit sizes into two categories: macro grits and micro grits. | |||||||||||||||||||||
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Macro grits |
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Macro grit sizes of sandpaper can be categorised into the following sub-types. | |||||||||||||||||||||
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Extra coarseExtra coarse grits are larger in size and are used for the fast removal of all kinds of materials, especially the initial sanding of an object, such as a hardwood floor. The average diameter of an extra coarse grit would be between 530 and 1815 micrometers. |
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CoarseCoarse grits are designed for the rapid removal of unwanted material. The average diameter of a coarse grit is between 336 and 425 micrometers. |
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MediumMedium grits are designed for the gentle removal of varnish or sanding bare wood in preparation for a finish. The average diameter of a medium grit is between 190 and 265 micrometers. |
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FineFine grits are not suitable for removing varnish or paint from wood. They are often used for sanding bare wood in preparation for a finish. They are also used to remove water stains from wood. The average diameter of a fine grit is between 115 and 162 micrometers. |
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Very fineVery fine macro grits are only used for the sanding of bare woods. The average diameter of a very fine macro grit would be between 66 and 100 micrometers. |
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There are various levels of grit available within the sub-types of macro grit, and these are classified differently by the CAMI and FEPA standards. Below is a table demonstrating how each standard classifies the sizes. | |||||||||||||||||||||
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Micro grits |
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Micro grit sizes of sandpaper can be categorised into the following sub-types. | |||||||||||||||||||||
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Very fineVery fine micro grit sandpapers are used for a sanding finish between consecutive coats, for example between a coat of paint and a varnish. The average diameter of a very fine micro grit is between 40.5 and 58.5 micrometers. |
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Extra fineExtra fine grits are designed for the initial polishing of wood. The average diameter of an extra fine grit is between 25.8 and 36 micrometers. |
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Super fineSuper fine grits are ideal to be used for the final sanding finish on a workpiece. Their average diameter is between 15.3 and 23 micrometers. |
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Ultra-fineUltra-fine grits can be used for the final sanding and polishing of thick layers of varnish and paint, in order to give a workpiece that finishing touch. Their average diameter is as small as 8.4 and 12.6 micrometers. |
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There are also various levels of grit available within the sub-types or micro grit, and these are classified differently by the CAMI and FEPA standards. Below is a table demonstrating how each standard classifies the sizes. | |||||||||||||||||||||
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What grit size should you choose? |
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When using sandpaper, it is best to start with a coarse to medium size grit if you need to remove any unwanted coatings such as varnish or paint. Macro grits are also used to even out a rough surface. | |||||||||||||||||||||
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For final sanding, you should move on to a finer grit size to give your workpiece a smoother finish. Don’t be tempted to skip straight from a coarse grit to a fine one during sanding, as this could actually cost you time rather than saving it. | |||||||||||||||||||||
