Sandpaper
This article's lead section may be too short to adequately summarize the key points. (December 2023) |
Sandpaper, also known as glasspaper or as coated abrasive, is a type of material that consists of sheets of
In the modern manufacture of these products, sand and glass have been replaced by other abrasives such as aluminium oxide or silicon carbide. It is common to use the name of the abrasive when describing the paper, e.g. "aluminium oxide paper", or "silicon carbide paper".There are many varieties of sandpaper, with variations in the paper or backing, the material used for the grit, grit size, and the bond.
Sandpaper is produced in a range of grit sizes and is used to remove material from surfaces, whether to make them smoother (for example, in painting and wood finishing), to remove a layer of material (such as old paint), or sometimes to make the surface rougher (for example, as a preparation for gluing). The grit size of sandpaper is usually stated as a number that is inversely related to the particle size. A small number such as 20 or 40 indicates a coarse grit, while a large number such as 1500 indicates a fine grit.
History
This section lists events whose chronological order is ambiguous, backward, or otherwise incorrect.(December 2023) |
The first recorded instance of sandpaper was in 13th-century China when crushed shells, seeds, and sand were bonded to parchment using natural gum.[2][3]
Glass paper was manufactured in London in 1833 by John Oakey, whose company had developed new adhesive techniques and processes, enabling mass production. Glass frit has sharp-edged particles and cuts well whereas sand grains are smoothed down and do not work well as an abrasive. Cheap sandpaper was often passed off as glass paper; Stalker and Parker cautioned against it in A Treatise of Japaning and Varnishing published in 1688.[5]
In 1921, 3M invented a sandpaper with silicon carbide grit and a waterproof adhesive and backing, known as Wet and dry. This allowed use with water, which would serve as a lubricant to carry away particles that would otherwise clog the grit. Its first application was in automotive paint refinishing.[6]
Backing
In addition to paper, backing for sandpaper includes cloth (
Fitting
A quick change system is commonly used with disc type coated abrasives. A plastic or metal hub is bonded to one of the faces, which is threaded. This then mates directly to the sander/grinder or to a mandrel that can be mounted in a sander, grinder, or drill. The advantage is that the disc can be quickly replaced when needed. Quick change discs range in sizes from 50 millimetres (2.0 in) to no upper limit.
Abrasives
Common substrates are
Types of abrasive materials include:
- Glass: No longer commonly used.
- Flint: No longer commonly used.
- Garnet: Commonly used in woodworking.
- Emery: Commonly used to abrade or polish metals.
- Aluminium oxide: The most common in modern use, with the widest variety of grits, lowest unit cost; can be used on metal (i.e. body shops) or wood.
- Silicon carbide: Available in very coarse grits all the way through to microgrits, common in wet applications.
- Alumina-zirconia: (An aluminium oxide–zirconium oxidealloy), used for machine grinding applications.
- Chromium(III) oxide: Used in extremely fine micron grit (micrometre level) papers.
- Diamond: Used for finishing and polishing hard metals, ceramics and glass.
- Ceramic aluminium oxide: Used in high pressure applications, used in both coated abrasives, as well as in bonded abrasives.
Sandpaper may be "stearated" where a dry lubricant is loaded to the abrasive. Stearated papers are useful in sanding coats of finish and paint as the stearate "soap" prevents clogging and increases the useful life of the sandpaper.
The harder the grit material, the easier the sanding of harder surfaces like hardwoods such as
Emery
Emery cloth is a type of coated abrasive that has
Emery was considered a suitable abrasive for
Both emery cloth and paper are still sold in hardware and
Emery is rated on the average grit size, glued to the backing. Common sizes are, from coarse to fine: 40, 46, 54, 60, 70, 80, 90, 100, 120, 180, 220, 320, F, and FF. A 46 or 54 grade cloth is used on roughly filed work, while 220 to 320 grit cloth will give a good polish.[8]
By the successive use of progressively finer mesh emery paper, near-mirror finishes can be obtained. Water or oil is often used as a lubricant and to float the abrasive debris and worn abrasive away from the work, preventing the build-up of debris in the emery paper. The paper will lose effectiveness if too much debris builds up, a condition known as "clogging", or "loading".
Originally, emery paper was made from milled emery rock, bonded or
Emery cloth has the abrasives bonded to a fabric instead of a paper. The cloth is more tear resistant, flexible, and costly.
Crocus
Crocus cloth is an abrasive sheet similar to sandpaper or emery cloth but covered with a layer of very fine loose iron oxide particles rather than with bound grains of abrasive. It is intended for final metal and gemstone finishing and is available in various grades (particle sizes). Federal Specification P-C-458 described this material in detail, although the specification was cancelled in 1989.[10]
Wet and dry papers
Abrasive papers and cloths with a waterproof backing allow the use of a lubricant, typically water, which can both decapitate rough surfaces when used dry and produce a semi-polished satin type finish when wet. Super-fine grades can produce a "key" adhesion surface appropriate for spray painting in critical decorative applications such as automotive bodywork repair[11][12]
Bonds
This section needs additional citations for verification. (September 2022) |
Different adhesives are used to bond the abrasive to the paper.
Sandpaper can be either closed coat or open coat.[13] Approximately 90% to 95% of the surface is covered with abrasive grains with a closed coat. Closed coat sandpaper is good for hand sanding or working with harder materials. In comparison, 50% to 70% of the surface is covered with abrasive grains with open coat sandpaper. The separation between particles makes the sandpaper more flexible, which prevents the sandpaper from clogging. However, the gaps in grit coverage limits the sandpaper's ability to perform even polishing jobs. Open coat sandpaper is better for softer materials.
Wet and dry sandpaper is more effective used wet because clogging is reduced by particles washing away from the grinding surface.[14]
Shapes
Sandpaper comes in a number of different shapes and sizes:
- Sheet: usually 9 by 11 inches (23 by 28 cm), but other sizes may be available
- Belt: usually cloth backed, comes in different sizes to fit different belt sanders.
- Disk: made to fit different models of disc and random orbit sanders. May be perforated for some models of sanders. Attachment includes pressure-sensitive adhesive (PSA) and "hook-and-loop" (similar to Velcro).
- Rolls: known as "shag rolls" by many contractors
- Sponge: for tight places
Grit sizes
This section needs additional citations for verification. (September 2022) |
Grit size refers to the size of the particles of abrading materials embedded in the sandpaper. These measurements are determined by the amount of the abrasive material that can fit through a square inch filter.[15] Several standards have been established for grit size. These standards establish not only the average grit size, but also the allowable variation from the average. The two most common are the United States CAMI (Coated Abrasive Manufacturers Institute, now part of the Unified Abrasives Manufacturer's Association) and the European FEPA (Federation of European Producers of Abrasives) "P" grade. The FEPA system is the same as the ISO 6344 standard. Other systems used in sandpaper include the Japanese Industrial Standards Committee (JIS), the micron grade (generally used for very fine grits). Cheaper sandpapers may sometimes only use descriptive nomenclature such as "coarse", "medium" and "fine" without referring to any standard.
See also
References
- ISSN 0161-7370.
- ^ Casey, Don (May 3, 2016). "Know How: Sandpapers and Sanding". Sail Magazine. Retrieved 1 February 2019.
- ISSN 0161-7370.
- ISBN 978-0-393-30868-6. Archivedfrom the original on 2014-06-27.
- ^ Stalker & Parker (1971) [1688]. A Treatise of Japaning and Varnishing. Tiranti.
- ISBN 978-0-87351-238-1. Archivedfrom the original on 2014-06-27.
- ^ Dwivedi, Kamal (17 June 2021). "What is Difference Between Emery Paper and Sandpaper?". Mechical. (blog). Retrieved 2023-03-10.
- ISBN 0-8311-2635-3.
- ^ Parker, John W.; Strand, West (1835). Minerals and Metals; Their Natural History and Uses in the Arts. Society for Promoting Christian Knowledge. p. 208.
- ^ "P-C-458 C Cloth Abrasive Crocus".
- ^ 3M™ Wetordry™ Sandpaper
- ^ "Abrasive Wet and Dry Paper". The Polishing Shop. Retrieved 2023-03-10.
- ^ "What is the Difference Between Open and Closed Coat Abrasives?". Red Label Abrasives. Retrieved 2020-07-07.
- ISBN 1558709436.
- ^ "Sandpaper Grit". Empire Abrasives. Retrieved 13 April 2020.
Further reading
- Dresdner, Michael (1992). The Woodfinishing Book. Taunton Press. ISBN 1-56158-037-6
- Flexner, Bob (2005). Understanding Wood Finishing — How to Select and Apply the Right Finish. Fox Chapel Publishing. ISBN Hardcover:978-1-56523-548-9. ISBN Paperback:978-1-56523-566-3