Sandpaper types of grit: table of sandpaper markings. Sanding paper for wood and metal

Skins by base type

Even in a small city, walking through hardware stores, you can find several dozen different samples of sandpaper. They will differ not only in grain size, but also in the method of applying the abrasive material, the type of filler and binder, as well as the abrasive material or mixture thereof used. However, in practice, the type of substrate on which the abrasive is applied is of primary importance.

The cheapest and most quickly consumed sandpaper is made on paper. It has few advantages: in addition to its low price, paper is convenient if you need to quickly tear off a fresh piece of paper for work. The abrasive from such sandpaper crumbles quite quickly, especially in fractured areas, but the paper base makes it easier to process raised surfaces.

Fabric-based skin has a slightly higher cost, but is much more durable. In many households you can find half a dozen scraps of cloth sandpaper lying around, which have been successfully used from time to time for several years and have not lost their abrasive qualities.

There are also some drawbacks: epoxy-impregnated fabric is rough, and the surface being treated is less noticeable underneath. Also, fabric sanding belts tend to stretch, although this mainly applies only to consumables for machine processing.

Finally, there is a third type of sanding paper – soft-backed sanding paper. This includes foam or polyurethane sandpaper, used for finishing textured wood and plaster parts, and fiber sandpaper. The latter, although it has similar properties in terms of pressing against the part, is used for attachment to a working tool with Velcro, for example, on rotary grinders.

Base

Abrasive paper can be made on different materials:

  • The bulk of products with abrasives are produced on a paper basis. To increase the strength of the paper web to tearing, abrasion, and bending, it is impregnated with polymers and resins. Thanks to these compositions, the product also acquires moisture-resistant properties. But still, paper is a fragile object and is not suitable for intensive long-term work. Fine grain is applied to it. Наждачная бумага: основа, виды зернистости, таблица маркировки
  •  Fabric-backed sandpaper is more resistant to abrasion and wear. The grain holds just as well, the canvas additionally has elasticity and resistance to moisture, intensive work with various materials, even with a sander, for which they produce velcro attachments. Наждачная бумага: основа, виды зернистости, таблица маркировки
  •  Combined fabric-paper fabric (two-layer) combines the best properties of previous materials. The product is elastic, resistant to abrasion, bending, and moisture. Coarse-grained sandpaper is produced on a combined basis.

On sale you can find paper with a sponge base. This type allows dust to pass through well, is not afraid of moisture, and is suitable for manual and mechanical work for a long time.

Sandpaper with coarse grain (coarse-grained – macrogrid)

  • The roughest work. Removing burrs and rust. (grain 1000 microns
    500 microns
    ) New GOST:
    P22, P24,P30, P36 (hereinafter the sequence is given in order of decreasing grain, i.e. P22
    — largest grain ( 1000 microns
    ), P36
    — smallest ( 500 µm
    )) Old GOST:
    80-P, 63-P, 50-P (hereinafter in order of decreasing grain, i.e. 80
    — largest grain ( 1000 microns
    ), 50
    — smallest ( 500 µm
    ))
    1. Rough woodwork. Pre-grinding of various surfaces ( 500 – 250 microns
      )
    2. New GOST:
      P40, P46,P54, P60
    3. Old GOST:
      40-P, 32-P, 25-P
  • Removing a layer of varnish, paint or drying oil. Elimination of uneven plaster. Intermediate grinding ( 250 – 100 µm
    ) New GOST:
    P70, P80,P90, P100 Old GOST:
    20-P, 16-P, 12-P, 10-P
    • Final sanding. ( 50 – 105 µm
      )
    • New GOST:
      P120, P150,P180, P220
    • Old GOST:
      20-P, 16-P, 12-P, 10-P

Sandpaper with fine grain (fine-grained – microgrid)

    1. Fine grinding ( 60 – 40 µm
      )
    2. New GOST
      : P240, P280,P320, P360
    3. Old GOST
      : 5-P, 4-P.
    • Polishing, “wet” grinding (using lubricants and cooling liquids). ( 40-20 microns
      )
    • New GOST
      : P400, P500,P600, P800
    • Old GOST
      : M40, M28, M20
  • Grinding of metal, plastic, ceramics. Finishing processing of any type of wood, leather products.

    ( 20-14 µm
    )

    New GOST
    : P1000, P1200

    Old GOST
    : M20

    1. Ultra-fine grinding, polishing of corrosion-resistant steels, production of micro-sections. ( 14-3 µm
      )
    2. New GOST
      : P1500, P2000, P2500
    3. Old GOST
      : M14, M10, M7, M5

It is also useful to understand what types of sandpaper are divided into in addition to the size of the abrasive grain and how this affects its functionality and cost.

Types of sandpaper grit

Depending on the abrasive crumb fraction, base material and purpose, the entire range of produced abrasive cloth can be divided into several modifications.

Based on grain size, the following types of sanding cloths are distinguished: fine-grained and coarse-grained. The table shows the grit values ​​of the most commonly used sandpaper:

Initial sanding, correction of minor surface defects

GOST R 52381-05 GOST 3647-80 Grit size, microns Scope of application
Coarse
Р22 80-N 800-1000 Pre-cleaning
Р24 63-N 630-800
Р36 50-N 500-630
Р40 40-N 400-500 Wood roughing
Р46 32-N 315-400
Р60 25-N 250-315
Р80 20-N 200-250 Initial sanding Correction of minor surface defects
Р90 16-N 160-200
Р100 12-N 125-160
Р120 10-N 100-125
Р150 8-N 80-100
  • Treatment of hardwood before final sanding
  • Sanding soft wood
  • Removing old paint
Р180 6-H 63-80
Fine sandpaper
Р240 5-H; M63 50-63 Finish sanding of hardwood Intermediate sanding
Р280 4-H; M50 40-50
Р400 M40; N-3 28-40
  1. Surface polishing
  2. Sanding for painting
  3. Wet grinding
Р600 M28; N-2 20-28
Р1000 M20; N-1 14-20 Sanding ceramics, plastics and metals Wet sanding
Р1200 M400 10-14 Polishing, deglazing
Р1500 M10; N-0 7-10
Р2000 M7; N-01 5-7
Р2500 M5; N-00 3-5

As can be seen from the grit table, the range of application of sandpaper is quite wide:

  • Carpentry and furniture industries;
  • Mechanical engineering and industrial production;
  • Manufacturing of non-standard equipment and instrumentation;
  • Car repair and painting;
  • Construction and finishing works.

This is far from a complete list, and the ways of using sandpaper in everyday life cannot be described at all due to its endless variety.

The most common are three forms of produced sanding cloths:

As for the release form, the most common are sheet and roll. In addition, there are ready-made ring modifications for scraping and hand grinders, disk pads for electric drills and some other varieties.

Types of grain size by material

The abrasive is made on different bases:

  • Silicon carbide (carborundum) is suitable for working with hard surfaces of metal and plastic.
  • Pomegranate grains are hard and soft at the same time: such abrasive paper is able to remove unevenness from the surface of the wood and seal the fibers, so that the paint or varnish coating applies evenly.
  • Ceramics are used to make coarse sandpapers used for smoothing wood.
  • Aluminum oxide is a material of considerable price, but its service life is impressive for its “compatriots”: soft crystals break during grinding, smoothing the surface, but in their place smaller particles with the same sharp edges are formed.
  • Diamond sandpaper is the most durable and expensive. It hardly wears out and is used mainly for machine processing of products in industry.

Manufacturing

Sandpaper production was first started in China in the 13th century. Craftsmen glued river sand of various sizes, crushed shell rock, and plant seeds to parchment using agar-agar or starch glue. Later they came up with the idea of ​​using crushed glass as an abrasive, hence the appearance of “glass paper.”

Serial production of sandpaper began in London in 1833, then began to spread throughout the world, technology improved, and today we see a variety of types of this product.

Production stages:

  1. The paper base or fabric is impregnated with polymers, most often rubber latex.
  2. Glue heated to 30…500C is applied to the prepared base.
  3. The abrasive of the required fraction is applied using the bulk method.
  4. The semi-finished product is sent to the oven for drying. The temperature depends on the type of glue, grain fraction and other factors.

In this way, you can make low-quality sandpaper at home using thick cardboard, crumbs from an abrasive wheel or crushed glass, sand.

Abrasives used

Several base abrasives are used to create the surface layer of sandpaper. In addition, each of them has many varieties, differing from each other in physical, chemical and technological characteristics. The main abrasives used to make sandpaper:

  1. Electrocorundum. An artificial material containing up to 99% aluminum oxide. Quite inexpensive and therefore the most common among abrasives. In addition to normal and white, a number of varieties are produced with the addition of titanium, chromium, zirconium compounds, etc.
  2. Silicon carbide. Compared to electrocorundum, it is more fragile, but exceeds it in hardness, therefore it is used mainly for metal work. Available in two types: green and black, which differ slightly in cutting properties.
  3. Garnet. A natural mineral, it is inferior in hardness to all others, but is self-sharpening well. The main application is grinding products made of soft materials.
  4. Elbor. Synthetic abrasive material based on boron nitride. It is somewhat inferior in hardness to diamond, but has better heat resistance.
  5. Diamond. Has the highest hardness. Diamond sandpaper is used for processing hard alloys and finishing tools.

In addition, sandpaper based on natural corundite (emery) and glass powder is still produced. The latter, in accordance with regulations, is used for grinding commutators of electric motors and generators.

How to choose sanding paper grit

Specialists from the technological department of the Belgorod Abrasive Department have developed recommendations for selecting grinding tools, depending on what material needs to be processed and what operation is being performed. Recommendations can be found in Table 2.

Table 2.

Р40, Р60, Р80

self-fastening sanding sheets and discs

Р100, Р120

self-fastening sanding sheets and discs

Р120, Р150, Р180

Table 2 shows the most common uses of sandpaper;

Flexible grinding tools are actively used in more than 50 segments. In addition to wood and metal, the materials processed can be stone, rubber, leather, glass, and plastic.

When selecting a tool, you can independently refer to our recommended tables, or contact the sales department specialists of BAZ OJSC and receive detailed information on the products.

Recommended articles:

Composition and scope of application of sanding paper.

Grinding grain: types, properties and applications.

Marking of abrasive soft material

Any sandpaper has its own code, which carries basic information about the material. The code contains the following information:

  • type of abrasive applied;
  • type of base material;
  • type of binder;
  • method of applying abrasive particles;
  • characteristics of the base;
  • water resistance.

It is interesting to note that before 2005, there was some confusion in the world regarding the labeling of sandpaper. Previously, GOST was used to record the markings of abrasive sanding material. Thus, according to this regulatory document, the grain size of the sanding material was recorded directly in the markings.

Thus, the size of abrasive particles could be seen on the material, which was indicated in tenths of microns. According to the new world standard, in the marking of grain size it is customary to record the number of individual sieve wires through which the abrasive is sifted per unit area (inch). Thus, it turns out that the smaller the abrasive particles on the sandpaper, the higher the number in the marking.

It should also be remembered that previously (until 2005) the grit size of sandpaper was marked on the back of the material with the letters “H” and “M”. However, you can now see the letter “P” on the back of the sandpaper.

The grit size of sandpaper is shown in Table 1. The full marking includes many letters and numbers that are not related to the grit size.

Table 1 – Grit and markings of abrasive sandpaper

Sandpaper grit types:

  • coarse-grained;
  • fine-grained.

Coarse-grain sandpapers include materials with an abrasive size from 63 to 1000 microns. The group of soft, fine-grained abrasive material includes sandpaper with grain from 3 to 63 microns.

Marking of sandpaper depending on its purpose: table

Depending on the specifics of the work, coarse sandpaper is divided into several main groups:

Operation to be performed Grit Tool
Processing of MDF boards, chipboards
calibration Р30, Р36, Р40, Р50 endless tapes
intermediate grinding Р50, Р60, Р80 endless ribbons
final sanding Р100, Р120, Р150 endless ribbons
Processing of furniture parts and doors from MDF
pre-sanding before priming Р80, Р100, Р120 self-fixing products
sanding after priming Р150, Р180, Р220, Р240 self-fixing products
sanding after painting Р320, Р400 self-fixing products
Processing of gypsum fiber and gypsum particle board
grinding Р24, Р30, Р36, Р40, Р60, Р80, Р100 endless tapes
Processing of furniture panels and furniture parts
calibration Р36, Р40, Р60, Р80 endless tapes
intermediate grinding Р100, Р120 endless tapes
fine grinding Р150, Р180, Р220 endless tapes
Processing of parquet boards
calibration Р80 endless tapes
intermediate grinding Р120 endless tapes
fine grinding Р150, Р180, Р220 endless tapes
Processing of rolled steel sheets
rough grinding, descaling Р24, Р30, Р36, Р40, Р50, Р60 endless tapes
intermediate grinding Р80, Р100, Р120 endless tapes
fine grinding Р150, Р180, Р220, Р240 endless tapes
polishing Р320, Р360, Р400, Р500, Р600, Р800, Р1000, Р1200 endless tapes
Stainless steel pipe processing
weld cleaning P40, P60, P80, P100, P120 endless tapes
pre-grinding, matting Р150, Р180, Р220, Р240 endless tapes
grinding Р280, Р320, Р360, Р400 endless tapes
fine grinding/polishing Р500, Р600, Р800, Р1000, Р1200 endless tapes
Carbon steel pipe processing
removal of scale, rust Р40, Р60, Р80 endless tapes
fine grinding Р100, Р120, Р150, Р180 endless tapes
Wire processing
grinding Р40, Р60, Р80, Р100, Р120, Р150 endless tapes
Processing of medical instruments, cutlery
rough grinding, deburring Р60, Р80, Р100 endless tapes
fine grinding Р100, Р120, Р150, Р180 endless tapes
Machining of radiators and aluminum parts
rough grinding, deburring Р40, Р60 endless tapes
fine grinding Р80, Р100 endless tapes
General metalworking
rough grinding Р36, Р40, Р60 flap wheels, self-fixing grinding discs
intermediate grinding Р80, Р100, Р120 flap wheels, self-fixing grinding discs
fine grinding Р150, Р180, Р220 flap wheels, self-fixing grinding discs
polishing Р240, Р320, Р360, Р400, Р500, Р600, Р800 flap wheels, self-fastening grinding discs
Paintwork treatment
preparing metal for coating

removal of old coating, rough leveling of putty

grinding rough scratches and marks on the surface of the prepared material;

pre-grinding, putties smoothing out marks from the previous abrasive, completing leveling;

preparation for applying filling primer; self-fastening sanding sheets and discs
final sanding of putty Р180 self-fastening sanding sheets and discs
surface preparation for priming Р220, Р240, Р320 self-fastening sanding sheets and discs
rough ground grinding Р400 self-fastening sanding sheets and discs
final ground grinding Р600, Р800 self-fastening sanding sheets and discs
sanding the primer when painting in dark colors Р1000 self-fastening sanding sheets and discs
sanding after painting, removing paintwork defects Р1000, Р1200, Р1500 self-fastening sanding sheets and discs
sanding paintwork after P1500 or immediately after painting Р2000, Р2500 self-fastening sanding sheets and discs

Marking Types of work
Р22; Р24;Р36 Preparatory work: removing rust Elimination of large surface defects
80-N; 63-N; 50-N
Р40; P46; Р60 Rough surface treatment
40-N; 32-N; 25-N
Р80; P90; P100; Р120 Pre-grinding
20-N; 16-N; 12-N; 10-N
Р150; Р180 Final grinding and finishing
8-H; 6-H

Fine-grained sandpaper is also marked according to specific uses:

Marking Types of work
Р240; Р280 Sanding hardwood
5-H; M63
Р400; Р600 Polishing surface preparation for painting
M28; M40; 2-H; 3-H
Р1000 Grinding of ceramic surfaces, plastics and metals
M20; 1-H
Р1200; P1500; P2000; Р2500 Polishing and deglazing
M14; M10; M7; M5; N-0;N-00; N-01

When purchasing sandpaper, other markings may be found on the reverse side. Each of them carries a certain meaning, for example, the type of abrasive powder, the method of its attachment, the characteristics of the adhesive mixture and the type of base and its mechanical properties. Let’s look at the basic notation.

  1. The name “P” indicates the abrasive structure of the material;
  2. The letter “L” denotes the form of release, in this case – sheet; The numbers “1” and “2” indicate the purpose of the abrasive cloth: 1 – for grinding soft surfaces, 2 – metal and other hard and especially hard materials;

    Resistance to moisture is indicated by the symbols “L1”, “L2” or M;

    The designation “P” indicates that exposure to moisture and dampness is extremely undesirable.

In addition to these designations, special attention must be paid to the properties of the abrasive particles themselves.

Sandpaper grit marking Marking of abrasive paper by grain size is regulated by domestic GOST 3647 and GOST 52381 and international standards FEPA P. The latter designation is more often found on the back of the product. It should be noted that GOST data and the values ​​of international standards overlap with each other.

Specialists from the Belgorod abrasive plant have developed recommended grain sizes according to GOST and FEPA P.

Conditional compliance with the grain size of the grinding grain according to GOST 3647, GOST 52381, FEPA P

Table 1.

P360, P400, P500

25-N

P600, P800

20-N

M20

16-N

P80

M14

12-N

P100

M10

P120

M7

P150

M5


P3000

GOST
3647,
GOST 52381
FEPA
P
GOST
3647,
GOST 52381
FEPA
P
100-N P20 6-H P180
80-N P24 5-H P220
63-N P30 M63 P240, P280
50-N P36 4-H P320
40-N P40 M50 Р320
32-N P50 M40
P60
M28
P1000, P1200
P1500

10-N

P2000, P2500
8-N
Conventionally, three categories of sanding paper grain size can be distinguished: Coarse grain.

Used for rough processing of material and cleaning it from paint and varnish. This skin has coarse and large grains. A coarse-grained grinding product is used when it is not necessary to smooth the surface, but to clean off the top layer. The sandpaper leaves deep scratches on the surface; further processing with less grainy sandpaper is needed. Grit numbers from P20 to P80. Medium grain. Used in intermediate processing. Cleans and smoothes the surface. The treated surface becomes smooth and even. This type of sandpaper leaves less deep scratches than coarse-grained sandpaper. Numbers from P80 to P180.

Fine-grained.

This sandpaper is used at the last stage of processing to sand the surface before painting. Zero-grit sandpaper, 0 or zero, also falls into this category. Numbers from P180 to P3000.

The above grit categories are just a generalized gradation. When choosing a grinding product, other parameters are important so that the result of the work meets expectations.

Depending on the conditions of use of the tool, the following must be observed:

Operations performed.

The material being processed and the degree of its processing (roughness). Characteristics of equipment and its condition, conditions of use. The latter include cutting speed, material feed, and load. Product consumption standards. Product characteristics: design, grain size, geometric dimensions, design features.

Abrasive material

I wasn’t too lazy to photograph the underside of the skin that the birdhouse was processing.

Resin bonded line – abrasive material, grinding material (according to the English – Russian dictionary of mechanical engineering and production automation)

If you look at the back of your sandpaper, you will most likely see a similar simple inscription aluminum oxide, which means aluminum oxide (in common parlance, electrocorundum). A possible option is silicon carbide or ceramic abrasive.

  • The first is a brittle material and is used for processing wood, alloy steel, and cast iron.
  • Second ( silicon carbide
    ) has high hardness and is designed to work with glass, plastic, and metal.
  • As a rule, this knowledge is enough for the general consumer to do housework, but for the sake of general development we suggest covering the topic more broadly:

Sandpaper

Sandpaper

is a well-known and widely used product. It is used in almost all areas related to production and repair.

Sandpaper is an abrasive material used for polishing work. It can correct surfaces with scratches and corrosion, and can be used for roughing and finishing.

Varieties of bases for sandpaper

Paper base

is the most popular because it has low cost and good grinding performance. Its main disadvantage is that it wears out quite quickly. Most fine grain skins are created on this basis.

Fabric base

more durable than paper base. Has excellent elasticity. Some manufacturers endow such paper with water-repellent properties by impregnating it with a special substance.

Combination foundation

was created by combining paper and fabric bases. This combination is universal. Has excellent abrasive properties. On this basis, skins with large grains are made.

Velcro base

is used as an abrasive pad for a sander.

Types of abrasive material for sandpaper

Powdered abrasive particles are applied to the sanding side of the paper. Abrasive materials are substances with increased hardness. They are made from natural or synthetic raw materials.

Garnet abrasive

is of natural origin. It is made by grinding pomegranate into a sandy mass. Paper with this abrasive is quite flexible. It has sharp grains and perfectly seals porous formations on the surface. Prepares the surface well for subsequent painting.

Silicon Carbide Abrasive

are colorless crystals and are a synthetic analogue of the natural mineral mussanite. Made by fusing silicon with carbon. Sometimes iron is added to its composition, which gives a dark pigment. Sandpaper with this abrasive is durable and sands most surfaces.

Ceramic abrasive

has increased rigidity. The raw material for this abrasive is a ceramic binder consisting of borosilicate frit, feldspar, liquid glass and other components. Effective for roughing.

Electrocorundum abrasive

is a crystalline aluminum oxide. It is distinguished by wear resistance due to the fact that particles of this raw material are subject to destruction during operation and form new edges. Polishes metal and wood surfaces well.

Sandpaper Markings

Abrasive paper is classified according to various standards. The most common is FEPA (ISO 6344

), it is international. In Russia, GOST R 52381-2005 is relevant, it is similar to the FEPA marking. The letter P in these standards indicates the degree of grain size. Grit refers to the number of abrasive particles per square inch.

In some former Soviet republics, USSR standards are still used (GOST 3647-80

). According to this marking, the number symbolizes the grain size in tens of microns. After it it is customary to put -N (10-N, 40-N). In the case when the size is indicated in microns, then M is placed before the number – micro (M14, M20).

Applications

Emery is used in many areas of production:

  • Many people find non-standard ways to use sandpaper in everyday life. For example:
  • Sharpening needles and scissors
    . It is enough to pierce the sandpaper with a needle several times to make it much sharper, and to sharpen the blades of scissors you need to cut the sandpaper 3-5 times.
  • Cleaning joints between tiles
    . It can be very difficult to remove dirt with cleaning products from between the tile seams. To do this, you need to bend a sheet of fine sandpaper in half and grout.
  • Cutting board update
    . Wooden cutting boards develop knife marks over time. These places can become a breeding ground for microorganisms. Using sandpaper you can sand the surface of the board.

When choosing sandpaper, you should pay attention not only to the price, but also to the characteristics:

  • Grit
    . How to choose the right sandpaper? The types of grain for metal or wood are determined depending on the purpose of the work: removing an old layer of paint, polishing or grinding.
  • Material – base
    . If leveling the surface will be done manually, there is no point in spending money on expensive products. A paper base may be quite sufficient.

So, the sandpaper must match the material that is supposed to be processed. To accurately select the right option, you should pay attention to the information indicated on the back of the sheet. If you study the basic markings, you will not have any difficulties with the choice, and you will be pleased with the quality of the work.

Areas of application of abrasives in accordance with the type of abrasive material

  • Electrocorundum normal
    (93-96% Al2O3 – for example 16A) such skins are intended for malleable cast iron, hardened and non-hardened steels, and wood.
  • White electrocorundum
    (Al2O3 no more than 99% – for example 25A) – for processing heat-resistant and alloy steels.
  • Silicon carbide
    (for example 64C) – finishing processing of metal, cast iron, bronze, aluminum, plastic, marble, granite, glass, wood.
  • Flint
    (for example 81K) – for processing wood, plywood, leather.
  • Glass
    (for example 71C) – for processing wood, plywood, felt, felt.
  • Garnet
    — for processing hard deciduous wood (oak, beech, etc.).
  • Elbor
    — for polishing precision surfaces and hard-to-machine steel parts.
  • Diamond
    — for polishing and fine honing of precision parts made of carbide and cast iron.

Popular manufacturers

On the Russian market, sandpaper is represented by two types of brands. The first are manufacturers of hand and power tools who sell various types of sandpaper under their own brands as consumables for their own products.

The second group includes enterprises specializing in the production of tools, including abrasive ones. For example, Fit sandpaper is offered by a well-known Canadian brand specializing in sales of all types of hand and power tools.

Among Russian manufacturers, the most famous is the Belgorod Abrasives Plant, and among foreign ones – the Finnish company Mirka and the famous international corporation 3M. The lion’s share of sandpaper on the Russian market is imported. It is mainly supplied from China under various brand names, although such a well-known brand as Mirka produces its sandpaper in Taiwan. Against this background, 3M looks the best, having built its own plant in Volokolamsk in 2008.

Grit definition

нулевая наждачка

Each type of sandpaper is assigned its own designation. The number next to the letter “P” indicates the size of the abrasive fraction. The higher this number, the finer the grain.

Маркировка наждачки

Please note! Paper marked P600 or more is considered fine-grain sandpaper. Used for final surface treatment and polishing.

In addition to the grain size designation, the material is sometimes marked depending on its special properties. For example, the letter “M” is characteristic of waterproof materials, and “P” excludes contact with moisture. Sheet metal is designated by the letter “L”.

Additionally, markings “1” or “2” may be present, the first of which indicates use for soft materials, and the second for hard materials.

Tips for sanding metal

When cleaning and grinding steel and cast iron, it is recommended to use sandpaper with abrasive grain made of electrocorundum on a waterproof base made of rigid or flexible (depending on the task) cotton fabric. In general, sandpaper type KK19XW with a grit appropriate for the type of sanding will be suitable.

It is recommended to process aluminum and its alloys with high-density paper-based sandpaper (220–270 g/m²) with electrocorundum grain, for example, such as KP13E. Copper alloys have different viscosity and brittleness. And if the same sandpaper is suitable for bronze as for ferrous metals, then more viscous brass is sanded with sandpaper with grains of white or zirconium electrocorundum on a cotton or polyester waterproof base.

If we missed anything important in the description of the features of using sandpaper when processing metals and other materials, please add our information in the comments to this article.

Old Gost

The old markings will look different. Standard sandpaper is marked first with a number indicating the grain size, and then with the letter “P”, “N” or “D”. These letters indicate the quality of the abrasive used to create the sandpaper.

Fine-grained skins are marked differently. The letter “M” is placed first, followed by the size of the abrasive in micrometers (µm).

Госты наждачки1

Table of grain size, purpose and markings

Sanding before painting

Wet sanding

P600

M28/H-2

M20/H-1 ​​

14-20
Grinding of metal, plastics, ceramics Wet grinding

P1200

M14

P2000

M7/N-01

5-7

M5/N-00
3-5

GOST R 52381-2005 (Russia) GOST 3647-80 (USSR) Grain size (µm) Appointment
Coarse
P22 80-H 800-1000 Roughing
P24 63-H 630-800
P36 50-H 500-630
P40 40-H 400-500 Rough woodwork
P46 32-H 315-400
P60 25-H 250-315
P80 20-H 200-250
  • Primary grinding
  • Surface smoothing
  • Removing small irregularities
P90 16-H 160-200
P100 12-H 125-160
P120 10-H 100-125
P150 8-H 80-100
  1. Preparing hard wood for sanding
  2. Final sanding of soft wood
  3. Sanding old paint for painting
P180 6-H 63-80
Fine grain
P240 5-H,M63 50-63 Final sanding of hardwood Sanding between coats
P280 4-N,M50 40-50
P400 M40/N-3 28-40
  • Polishing final coats
20-28 P1000

10-14 Even finer grinding, polishing Removing gloss, stains, micro-scratches
P1500

M10/N-0

7-10

P2500

Release form

The finished product is available in several forms. Available in the form of sheets or rolls. The leaf shape is characteristic of large fractions that are difficult to bend or roll. Fine-grain paper is available in roll form.

In addition to these forms there are also:

abrasive mesh; abrasive wheels; sanding belts. The form can be intended for installation in a specific mechanism for processing parts and have a specific appearance.

Sandpaper release form

Abrasive paper is used not only for manual sanding, but also for machine sanding, so it comes in a wide variety of forms.

  1. Leaf. Typically sold in 280×230 sheets. Some brands offer sets of 4-6 sheets in different grits. This type of sandpaper is used in oscillatory sanders, whose pad is usually 280 mm long and 93 or 115 mm wide.
  2. Rolled. Most often, sandpaper is sold in rolls 5 m long and 93 or 115 mm wide, which corresponds to the width of a hand holder or the base of an oscillating sander. In addition, in stores you can find rolls of sandpaper several tens of meters long and up to a meter wide. This material is intended for cutting into rolls of smaller width or individual sheets.
  3. Disc and triangular. These forms of sanding sheets are used in orbital and delta sanders and are available in two types: for fastening with clips and self-adhesive (“Velcro”). As a rule, both forms have 6–8 holes on the surface to remove dust from the surface being processed (see photo below – in the foreground).
  4. Tape. In stationary and manual belt sanders, sandpaper is used in the form of a continuous belt rotating between several rollers. Depending on the type of equipment, its length can range from tens of centimeters to several meters.
  5. Cylindrical. This shape is used in drum machines and for grinding using cylindrical equipment. Наждачка в рулонах

In addition, sandpaper is an integral part of flap brushes. In this case, it is used in the form of many narrow lamellas of abrasive paper, fixed at one end along the entire circumference of the central sleeve (see in the photo above – left in the background).