View source for Sandpaper

{{Short description|Abrasive material used for smoothing softer materials}}
{{Redirect|Sanding|the fish known as sanding|Pseudaphritis urvillii}}
{{Lead too short|date=December 2023}}
[[File:Schleifpapier verschiedene Sorten.jpg|thumb|upright=1.35|Sheets of sandpaper with different grit sizes (40 (coarse), 80, 150, 240, 600 (fine))]]

'''Sandpaper''', also known as '''coated abrasive''' or '''emery paper''', is a type of material that consists of sheets of [[paper]] or [[cloth]] with an [[abrasive]] substance glued to one face.<ref>{{Citation | last = Hill | first = Ray | title = PS guide to sandpaper and other coated abrasives | journal = Popular Science | volume = 211 | issue = 1 | page = 106 | date = July 1977 | url = https://books.google.com/books?id=LAEAAAAAMBAJ&pg=PA106 |issn=0161-7370}}.</ref> In the modern manufacture of these products, sand and glass have been replaced by other abrasives such as aluminium oxide or silicon carbide.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 [[house painter and decorator|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 [[adhesive|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 ==
The first recorded instance of sandpaper was in 13th-century [[China]] when crushed shells, seeds, and [[sand]] were bonded to parchment using [[natural gum]].<ref>{{cite journal |last1=Casey |first1=Don |title=Know How: Sandpapers and Sanding |journal=Sail Magazine |date=May 3, 2016 |url=https://www.sailmagazine.com/diy/know-sandpapers-sanding |access-date=1 February 2019}}</ref><ref>{{Citation | last = Parker | first = Jerry | title = How to choose the right coated abrasive | journal = Popular Science | volume = 180 | issue = 4 | page = 159 | date = April 1962 | url = https://books.google.com/books?id=LCEDAAAAMBAJ&pg=PA159 |issn=0161-7370}}.</ref>

[[Shark]] skin ([[placoid scales]]) has also been used as an abrasive, and the rough scales of [[coelacanth]]s are used for the same purpose by the natives of [[Comoros]].<ref>{{Cite book|url=https://books.google.com/books?id=Ex2Nr3lLzM0C&pg=PA60|title=Living Fossil: The Story of the Coelacanth|first=Keith Stewart|last=Thomson|publisher=W. W. Norton & Company Limited|year=1992|isbn=978-0-393-30868-6|url-status=live|archive-url=https://web.archive.org/web/20140627025033/http://books.google.com/books?id=Ex2Nr3lLzM0C&pg=PA60|archive-date=2014-06-27}}</ref> Boiled and dried, the [[Equisetum hyemale|rough horsetail]] plant is used in Japan as a traditional polishing material, finer than sandpaper.

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.<ref name="Stalker & Parker 1688">{{cite book |first1=John |last1=Stalker |first2=George |last2=Parker |year=1971 |orig-year=1688 |title=A Treatise of Japaning and Varnishing |url=https://archive.org/details/treatiseofjapann0000stal |url-access=registration |location=London |publisher=Alec Tiranti |oclc=1947744}}</ref>

Glass paper was manufactured in [[London]] in 1833 by [[John Oakey (inventor)|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.

In the United States, a major development in the history of coated abrasives was the work of [[Henry Hudson Barton]]. After emigrating from England in 1846, Barton married into a Philadelphia sandpaper manufacturing family. Drawing on his knowledge of gem minerals, he began experimenting with [[Gore Mountain Garnet|Adirondack garnet]] as an abrasive. Barton went on to establish mining operations at [[Gore Mountain (New York)]], in 1878, creating what became the world’s oldest continuously operating garnet mine. Garnet from Barton Mines was widely adopted in coated abrasives and further developments in sandpaper and remains a significant abrasive mineral today.<ref>{{Cite conference |last1=Kelly |first1=William M. |last2=Hill |first2=Mary Louise |date=1995 |editor-last=Garver |editor-first=J.I. |editor2-last=Smith |editor2-first=J.A. |title=Geology and Mining History of Barton Mines Corporation, Gore Mountain Mine |url=https://www.nysga-online.org/wp-content/uploads/2019/06/NYSGA-1995-B9-Geology-and-Mining-History-of-Barton-Mines-Corporation-Gore-Mountian-Mine.pdf |conference=Field Trips for the 67th Annual Meeting of the New York State Geological Association |location=Schenectady, NY |publisher=New York State Geological Survey / Union College |pages=405–412}}</ref>

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.<ref>{{Cite book|chapter-url=https://books.google.com/books?id=NxNlGsE7EVwC&pg=PA234|title=Minnesota in a Century of Change: The State and Its People Since 1900|first=Kirk|last=Jeffrey|editor-first=Clifford Edward|editor-last=Clark|publisher=Minnesota Historical Society Press|year=1989|isbn=978-0-87351-238-1|page=234|chapter=The Major Manufacturers: From Food and Forest Products to High Technology|url-status=live|archive-url=https://web.archive.org/web/20140627122427/http://books.google.com/books?id=NxNlGsE7EVwC&pg=PA234|archive-date=2014-06-27}}</ref>

== Backing ==
[[File:SCSandpaper.jpg|thumb|left|320 grit silicon carbide sandpaper, with close-up view]]

In addition to paper, backing for sandpaper includes cloth ([[cotton]], [[polyester]], [[rayon]]), [[PET film (biaxially oriented)|PET film]], "fibre", and rubber. Cloth backing is used for sandpaper discs and belts, while PET film is used as backing for extremely fine grits. Fibre or [[Vulcanization|vulcanized]] fibre is a strong backing material consisting of many layers of polymer impregnated paper. The weight of the backing is usually designated by a letter. For paper backings, the weight ratings range from "A" to "F", with A designating the lightest and F the heaviest. Letter nomenclature follows a different system for cloth backings, with the weight of the backing rated J, X, Y, T, and M, from lightest to heaviest.<ref>{{Cite web |title=What are the different types of backings used in coated abrasives? |url=https://www.preferredabrasives.com/faq/different-types-backings-used-coated-abrasives/ |archive-url= |archive-date= |website=preferredabrasives.com}}</ref> A flexible backing allows sandpaper to follow irregular contours of a workpiece; relatively inflexible backing is optimal for regular rounded or flat surfaces. Sandpaper backings may be glued to the paper or form a separate support structure for moving sandpaper, such as used in sanding belts and discs. Stronger paper or backing increases the ease of sanding wood. The harder the backing material, the faster the sanding, the faster the wear of the paper and the rougher the sanded surface.

== Fitting ==

[[File:Quick Change Disc.jpg|thumb|Examples of sanding discs using a quick-change mounting system]]

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]] or [[angle 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 are available in sizes of about {{convert|50|mm}} and larger.

== Abrasives ==
[[File:Emery cloth sheet - 01.jpg|thumb|Emery cloth sheet whose component [[abrasive]] is aluminium oxide]]
[[File:Assorted coated abrasives.JPG|thumb|Assorted coated abrasives]]

Common substrates are [[paper]], cloth, vulcanized fiber, and [[plastic]] films and come in grit sizes range from very coarse (≈2&nbsp;mm) to [[Ultrafine particles|ultrafine]] (sub[[micrometre]]). The [[international standard]] for coated abrasives is [[ISO 6344]].<ref>{{Cite web |title=ISO 6344-3:2021 |url=https://www.iso.org/standard/78219.html |access-date=2025-09-12 |website=ISO |language=en}}</ref> Sandpaper and [[emery cloth]] are coated abrasives for hand use, usually non-precision. Other coated abrasive forms include sanding cords, pads, belts, and discs. Variants are available for use by hand or as components for [[power tool]]s such as [[sander]]s, [[die grinder]]s and [[belt sander]]s.

Types of abrasive materials include:<ref>{{Cite web |last=Abrasives |first=Red Label |title=Abrasives 101|url=https://www.redlabelabrasives.com/pages/sandpaper-buying-guide |access-date=2025-09-14 |archive-url=https://web.archive.org/web/20250914163527/https://www.redlabelabrasives.com/pages/sandpaper-buying-guide?srsltid=AfmBOooVjSCdp0W5g5bNSC_23WdPQWFj1id4TszZX-Te5BSQ0XU-5Mlm|archive-date=14 September 2025|website=Red Label Abrasives |language=en}}</ref><ref>{{Cite web |title=What are the different types of abrasive grain? |url=https://www.preferredabrasives.com/faq/different-types-abrasive-grain/ |access-date=2025-09-14 |website=Preferred Abrasives |language=en-US}}</ref>

* [[Glass]]: No longer commonly used.
* [[Flint]]: No longer commonly used.
* [[Garnet]]: Commonly used in [[woodworking]].
* [[emery (mineral)|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.
* [[Zirconia toughened alumina|Alumina-zirconia]]: (An aluminium oxide–[[zirconium oxide]] alloy), 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.
* [[Aluminium oxide|Ceramic aluminium oxide]]: Used in high pressure applications, used in both coated abrasives, as well as in bonded abrasives.

Sandpaper may be "[[stearic acid|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 [[hickory]], [[pecan]], or [[wenge]]. The grit material for polishing [[granite]] must be harder than granite.

=== Emery ===
[[File:320 emery cloth.JPG|thumb|320 grit emery cloth]]

Emery cloth is a type of coated abrasive that has [[emery (rock)|emery]] glued to a [[cloth]] backing. It is used for hand metalworking. It may be sold in sheets or in narrow rolls, typically 25 or 50&nbsp;mm wide, often described as "emery tape". The cloth backing makes emery cloth stronger in tension than paper, but still allows a sheet to be conveniently torn to size. Emery (largely displaced by improved products such as aluminium oxide and silicon carbide) is used for scrubbing highly abraded and rough surfaces to a smooth and shiny finish, notably in watchmaking.<ref>{{Cite web|title=What is Difference Between Emery Paper and Sandpaper?
| website= Mechical | publisher= (blog)
| date= 17 June 2021
|url=https://www.mechical.com/2021/06/difference-between-emery-paper-and-sand-paper.html|access-date=2023-03-10|first=Kamal|last=Dwivedi}}</ref> [[Emery paper]], more commonly seen, has a paper backing and is usually a finer grit.

Emery was considered a suitable abrasive for [[fitter (occupation)|fitting]] work and the final adjustment of steel parts for a perfect fit. It had the advantage that, unlike harder abrasives, it was not considered to embed abrasive traces in the polished components afterwards. Emery was also used for cleaning, as a means of removing rust from polished steel components.

Both emery cloth and paper are still sold in hardware and [[do it yourself]] stores, but have been largely supplanted by the increased use of machine grinding to precision size, which has minimized or eliminated the need for hand-fitting; the widespread availability of powered hand tools employing sanding and grinding accessories such as [[flapwheel]]s; and a shift to other forms of abrasive, such as [[aluminium oxide]], [[aluminium alloys|aluminium zirconia]] and [[silicon carbide]].

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 [[polishing (metalworking)|polish]].<ref name="Machinery's Handbook, 1440">{{cite book |last1=Oberg |first1=Erik |title=[[Machinery's Handbook]] |last2=Jones |first2=Franklin D. |last3=Horton |first3=Holbrook L. |last4=Ryffel |first4=Henry H. |publisher=Industrial Press Inc. |year=2000 |isbn=0-8311-2635-3 |edition=26th |place=New York |pages=1440 |ref=Machinery's Handbook}}</ref>

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 [[Sizing|sized]] to paper often with an [[Adhesive#Natural adhesives|animal glue]] for water resistance.<ref>{{cite book |last1=Parker |first1=John W. |title=Minerals and Metals; Their Natural History and Uses in the Arts |last2=Strand |first2=West |publisher=[[Society for Promoting Christian Knowledge]] |year=1835 |page=208}}<!-- IS "STRAND WEST" AN AUTHOR? --></ref> Today, [[Adhesive#Synthetic adhesives|synthetic adhesives]] are used in place of natural glues and [[Silicon carbide#Abrasive and cutting tools|silicon carbide]] (SiC) is often substituted for emery, silicon carbide being slightly [[Mohs scale of mineral hardness|harder]], and more durable with less tendency to fracture than corundum. The use of natural emery papers is rare today generally being replaced with silicon carbide or pure aluminium oxide papers.

Emery cloth has the abrasives bonded to a fabric instead of a paper. The cloth is more tear resistant, flexible, and costly. [[Emery board]]s have applications similar to emery paper or cloth. It also has a use in modelling. For [[OO gauge|00 scale]] modelling, the fine grades of emery paper can have the appearance of a [[Asphalt concrete|tarmac]] surface.

=== 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.<ref>{{Cite web |title=P-C-458 C Cloth Abrasive Crocus |url=http://everyspec.com/FED_SPECS/P/P-C-458C_43809/}}</ref>

== 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.<ref>{{Cite web |url=https://www.3m.com/3M/en_US/p/d/b40071145/ |title=3M™ Wetordry™ Sandpaper |access-date=2022-09-05 |archive-date=2022-09-05 |archive-url=https://web.archive.org/web/20220905091340/https://www.3m.com/3M/en_US/p/d/b40071145/ |url-status=dead }}</ref><ref>{{Cite web|title=Abrasive Wet and Dry Paper|url=https://www.thepolishingshop.co.uk/abrasives/wet-dry-abrasive-paper|access-date=2023-03-10|website=The Polishing Shop}}</ref>

== Bonds ==
{{More citations needed section|date=September 2022}}
Different adhesives are used to bond the abrasive to the paper. [[Hide glue]] is still used, but this glue often cannot withstand the heat generated during machine sanding and is not waterproof. Waterproof sandpapers or wet/dry sandpapers use a resin bond and a waterproof backing.

Sandpaper can be either ''closed coat'' or ''open coat''. 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 when used wet because clogging is reduced by particles being washed away from the grinding surface.<ref>{{cite book |last1=Stack |first1=Jim |title=Box by box |date=2006 |publisher=Popular Woodworking Books |location=Cincinnati, Ohio |isbn=1558709436}}</ref>

== Shapes ==
{{Unreferenced section|date=April 2022}}

Sandpaper comes in a number of different shapes and sizes:

* Sheet: usually {{convert|9|by|11|in|cm}}, but other sizes may be available
* Belt: usually cloth-backed, comes in different sizes to fit different [[belt sander]]s.
* 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 fastener|hook-and-loop]]" (similar to Velcro).
* Rolls: known as "shag rolls" by many contractors
* Sponge: for tight places

== Grit sizes ==
[[File:Liivapaber-karedusindeksid.jpg|thumb|Grit sizes]]

Sandpaper grit is the size of the abrasive particles attached to the sandpaper. All grits are defined by a size distribution of the abrasive particles. For coarser grits ("macrogrits"), this distribution is determined by measuring the fractions of abrasive particles that pass through a series of successively finer test sieves, whereas for finer grits ("microgrits"), sedimentation-based techniques are used.<ref>{{Cite book |last=Linke |first=Barbara S. |title=Life Cycle and Sustainability of Abrasive Tools |date=2016 |publisher=Springer International Publishing AG |isbn=978-3-319-28345-6 |series=RWTHedition Ser |location=Cham}}</ref> This system is in place to maintain consistency across different companies.<ref>{{cite web |title=What is Sandpaper Grit? Your Complete Guide to Understanding Abrasive Particles |url=https://benchmarkabrasives.com/blogs/sanding/what-is-sandpaper-grit |access-date=31 July 2025 |website=Benchmark Abrasives |date=31 July 2025 }}</ref> The particle size of a grit is roughly equal to 2/3 inch divided by "grit size" number.<ref>{{cite web | url=https://de.wikipedia.org/wiki/Schleifpapier | title=Schleifpapier }}</ref> For example, "100 grit" sandpaper has particle size near 0.160&nbsp;mm (0.0064&nbsp;inch). Several standards have been established for grit size and permissible tolerances. The two most prevalent standards 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.<ref name="Rochester">{{cite web |last=Roche |first=James |title=Grit Size Comparison Chart |url=https://www.cs.rochester.edu/u/roche/rec.wood.misc/grit.sizes.html |url-status=live |website=}}</ref> The FEPA system is the same as the [[ISO 6344]] standard. Other systems used in sandpaper are those defined by the [[Japanese Industrial Standards Committee]] (JIS) and 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 ==
* [[Grain size]]
* [[Lapping film]]
* [[Sanding block]]
* [[Steel abrasive]]

== References ==

{{reflist}}

== Further reading ==
* Dresdner, Michael (1992). ''The Woodfinishing Book''. Taunton Press. {{ISBN|1-56158-037-6}}.
* Flexner, Bob (2005). [https://archive.org/details/isbn_9780762106219/mode/2up ''Understanding Wood Finishing: How to Select and Apply the Right Finish''] {{registration}}, rev. and updated ed. Fox Chapel Publishing. {{ISBN|978-1-56523-548-9}} (hardcover), {{ISBN|978-1-56523-566-3}} (paperback).

== External links ==
{{commons category}}

* [http://www.fepa-abrasives.org Federation of European Producers of Abrasives]
* [http://www.sizes.com/tools/sandpaper.htm sizes.com on sandpaper]
* [http://www.fine-tools.com/G10019.htm Conversion Chart Abrasives - Grit Sizes]

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