Sanding paper (sandpaper) – classification, marking and basis, application and GOST. – Tool Mecca

Main classification

The most important characteristic is the grain size of the material, which determines the scope of its application – roughing, grinding, polishing. According to current international standards and those adopted in Russia since 2005, grain size is determined by the number of grains per square inch.

Accordingly, the more grains are placed per unit area, the smaller their size. According to this standard, the grain size of the material is reflected by the letter P and a number from 12 to 2500. According to the old GOST 3647-80, often used in the CIS countries, the number indicates the grain size in tens of microns with the letter –H at the end (6-N, 16-N, 32-N, etc.). The smallest grains are measured in microns and are designated M, for example M40.

https://www.youtube.com/watch?v=iGTEEmhxj2M

You can study the scope of application, marking and grain size according to various standards in the table below

Purpose of sandpaper, grit and markings.
Appointment Marking according to GOST 3647-80 Marking according to ISO-6344 Grain size, microns
Coarse
Very rough work 80-N P22 800-1000
63-N P24 630-800
50-N P36 500-630
Rough work
40-N P40 400-500
32-N P46 315-400
25-N P60 250-315
Primary grinding 20-N P80 200-250
16-N P90 160-200
12-N P100 125-160
10-N P120 100-125
Final sanding of soft wood, old paint for painting 8-N P150 80-100
6-H P180 (P 220) 63-80
Fine grain
Final sanding of hardwood, sanding between coats 5-N,M63 P240 50-63
4-Н,М50 P280 40-50
Final polishing, sanding between coats, wet sanding M40N-3 P400 28-40
М28Н-2 P600 20-28
Grinding of metal, plastics, ceramics, wet grinding M20N-1 P1000 14-20
Even finer grinding, polishing M14 P1200 10-14
M10/N-0 P1500 7-10
M7N-01 P2000 5-7
М5Н-00 P2500 3-5

The type of abrasive is also an important indicator. The most widely used is electrocorundum, characterized by resistance to high pressure and good cutting properties. It can be produced with the addition of chromium oxide, which increases the abrasive properties and strength of the material. It can be recognized by its characteristic ruby ​​color.

Among other grain materials, we note the following:

  • Silicon carbide. Stronger than electrocorundum, but more fragile. Thanks to this, the crystals split under pressure and form new faces, thereby renewing the surface.
  • Garnet. A relatively soft mineral, used mainly for wood processing.
  • Elbor and diamond. Superhard materials. Rarely used due to high cost.

Table of sandpaper grit types

Application

Grain size, microns

ISO 6344 marking

Marking GOST 3647-80

Fine grain

Finishing hardwood

50-63

R 240

5-N, M63

40-50

R 280

4-N, 50M

Sanding before painting, wet leveling

28-40

R 400

M40/N-3

20-28

R 600

M28/N-2

Plastic, glass, ceramics

14-20

R 1000

M20/N-1

High gloss polishing of all types of materials

10-14

R 1200

M14

7-10

R 1500

M10/N-0

5-7

R 2000

M7/N-01

3-5

R 2500

M5/N-00

Coarse grain

Corrosion removal, burr treatment

800-1000

R 22

80-N

630-800

R 24

63-n

500-630

R 36

50-N

Rough woodwork

400-500

R 40

40-N

315-400

R 46

32-N

250-315

R 60

25-N

Stripping wood fibers, removing plaster, putty

200-250

R 80

20-N

160-200

R 90

16-N

125-160

R 100

12-N

100-125

R 120

10-N

Removing protective coatings

80-100

R 150

8-N

63-80

R 180

6-H

How to choose sandpaper

For grinding machines, are there special sandpapers of various shapes (circle, triangle, rectangle) with a Velcro base? Such paper does not lose its shape for a long time and is suitable for long-term and continuous use. They are very easy to replace and are available for free sale in any construction department.

The most common type is paper-based sandpaper. This is what is most often found in home workshops. The paper base goes through special stages of processing and impregnation to maximize strength and moisture resistance.

The mesh for grouting putty is marked identically to paper: the larger the number, the smaller the abrasive particle. The degree of sanding is chosen depending on what subsequent action will be performed on the putty. The walls are sanded manually or using special machines. For manual application, use a kind of grater, onto which a piece of mesh is attached and evenly passed over the desired area.

Sandpaper on a sponge will help you reach hard-to-reach areas. It also makes it easier to clean parts of complex shapes. The sponge can be hard or soft. The hard one is used for flat surfaces, the soft one for curved surfaces.

Marking of sandpaper depending on its purpose: table

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

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 Hardwood sanding
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, you may find other symbols on the back 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;
  3. 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;
  4. Resistance to moisture is indicated by the symbols “L1”, “L2” or M;
  5. 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.

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 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.

Base

Abrasive paper can be made on different materials:

  • The bulk of products with abrasive 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 one allows dust to pass through well, is not afraid of moisture, and is suitable for manual and mechanical work for a long time.

Old Gost

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

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 wood work. 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

Release form

Наждачная бумага или шлифовальная шкурка- виды, типы, зернистость1

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 with fine grain (fine-grain – 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 fluids). ( 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 microns
    )

    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.

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.

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.

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:

Types of grain size by material

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.

Marking

Sandpaper markings indicate the fraction and concentration of the abrasive. Domestic GOST 3647-80 determines the number of grains of different sizes per 1 square unit, but this classification is considered outdated.

Today, sanding paper complies with international ISO standards; this designation can be found on the back of the product. It should be noted that the data of the old GOST and the values ​​of international standards overlap with each other.

Their correspondence can be seen in the table.

The main difference between the old and new standards is the different movement of numbers in the markings:

  • In GOST 3647-80, the values ​​of grain size and density decrease, which is quite logical;
  • In the new ISO 6344 standard (GOST 52318-2005), the product number increases with decreasing value in the marking.

What is the difficulty?

Today in stores you can find sanding paper marked both according to Russian GOST and the standards of other countries.

The confusion is that domestic markings on the skin can be made according to the new GOST of 2005 (focused on European standards) and according to the GOST of the 80s, approved by the Ministry of Machine Tool and Tool Industry of the USSR.

The two categories of standards are inverse. In the old GOST 3647-80, a decrease in marking numbers meant a decrease in grain size. In the new GOST, the abrasive grain decreases, but the number in the marking, on the contrary, increases.

In addition, there is no unity among global manufacturers. The USA and Canada, Europe and Turkey, Japan, China adhere to their own standard.

Explanation

Type of binder: M – flesh glue; C – synthetic resin; K – combined ligament.

In the old GOST, the sixth letter indicated the class of the abrasive – the number of defects. And no more than 0.5%; B – no more than 2%; B – no more than 3%.

Therefore, the number of defects (A) on the working surface of our example is no more than 0.5%.

or (new European standard using German VSM sandpaper as an example)

Example: KK X P150

Electrocorundum abrasive ( K
) on fabric ( K
) and hard ( X
) basis with grit P150
(75-106 microns).

Russian GOST marking

Mirka Abrasive Roll

When purchasing sandpaper, you should always pay attention to the markings. It contains information about the product. On sale you can find skins marked with both the new GOST and the old one.

How to determine sandpaper grit

Sandpaper grit is a measure of how many abrasive particles fit onto a square inch of substrate. The grain size is indicated in the markings of the specific sandpaper. There are three classes of sandpaper based on grain size:

  • large (from 12 to 80);
  • average (from 80 to 160);
  • fine (from 160 particles).

Coarse sandpaper is used for primary processing of materials, cleaning surfaces from dirt, etc. Fine-grained is used for polishing and fine cleaning.

The medium one is considered universal and can perform the functions of both large and small with equal efficiency. But this efficiency is much lower.

It is best to use this type of sandpaper to remove scratches on the surface.

Tips for using sandpaper

Try to avoid direct contact with water. This way the product may lose its properties, and it will be difficult to achieve the desired effect.

The mesh is easy to clean due to its large mesh. While working, periodically shake off dust or tap it on a nearby object or palm.

Use a flexible sander or sponge to easily get into dents or deep holes.

Don’t forget to have sandpaper in your pantry. It can come in handy at any time, both in the house and in the car.

While working, protect the skin of your hands: wear disposable protective gloves to avoid damaging your fingers. Remember, the material tends to heat up with prolonged friction!

Cloth sandpaper

Today, the most common base fabrics are cotton and polyester. Fabric-based abrasives most often have water-resistant properties due to a special resin-based impregnation.

L1, L2 and M – moisture-resistant paper.

Such sandpapers have a higher safety margin compared to paper ones.

The manufacturer may indicate 1 or 2 in the first digit marking.

  • 1
    — the sandpaper is intended for materials of low hardness (putty, primer, paint, enamel, soft wood, plastic)
  • 2
    – for hard metal alloys.

Sandpaper markings: grit table, types of abrasive

Although the blade itself is not difficult to manufacture and contains only two main components, understanding the markings of sandpaper is not always easy. This is due to the fact that there is no single standard even in the Russian Federation, not to mention the CIS and global manufacturers. Despite this, to make the right choice, you need to be able to decipher sandpaper symbols.

Currently, the widest range of abrasive components is used for the manufacture of grinding materials. In addition, there are several base options. Below we will consider the criteria by which you need to choose sandpaper for a particular type of work.

Sandpaper for wood

Wood is considered a softer material, so sandpaper should be selected differently. For processing wooden products, abrasives from:

are used

  • grenade;
  • ceramics;
  • aluminum oxide.

Moreover, each type is used at a certain stage of part manufacturing. Ceramics is used during the formation of the product, as it has high hardness and durability. Garnet and aluminum oxide are used at the stage of painting and leveling the surface.

For wood, choose coarse-grained paper with noticeable gaps between the abrasive particles. The base can be any and depends on the intensity of use.

Sandpaper for metal

For metal, it is best to use sandpaper with silicon carbide abrasive. This material is considered strong enough to handle hard surfaces. It can easily cope with rust, old paint or simply dirt.

You can choose any base, but it is preferable to choose a combination one. Increased strength and the possibility of impregnation will allow you to choose a universal sandpaper for processing.

Attention! When choosing sandpaper for metal, you need to make sure that the number “2” is present in the marking. This means that the sandpaper can be used for hard materials.

Grit table

Соответсвие зернистости и материала

Types of grit and sandpaper markings

instrument.guru > Manual > Types of grit and markings of sandpaper

Sandpaper grit (table)

Grit – the ratio of the amount of abrasive material applied to a square of the surface of the base. This is the main indicator of the use of sandpaper. The more abrasive is placed per unit area, the smaller the grain size. And the less abrasive, the larger the crystal.

According to the grain size, sandpaper is divided into three categories:

Sandpaper is also classified according to the substances that make up the abrasive. Among them:

Paper based

The bulk of all sandpapers are paper-based sandpapers. Paper is considered a convenient, cheap, but short-lived material. Intensive work with sandpaper will inevitably lead to abrasion of the base.

The service life is somewhat extended by a special impregnation that is applied to the paper during production. Impregnation is a type of polymer or rubber. Treated paper has increased strength and elasticity properties.

In addition, the abrasive adheres much better to the impregnated surface.

Full explanation of sandpaper markings

So, we already understand something and can try to read what the manufacturer had in mind.

For example, this marking (old GOST)

Example: 2 830×50 S2G 24A 40-NMA GOST 5009-82.

Abrasive for processing hard metal alloys

    , in a roll (830 mm by 50 m) on a fabric basis – twill (S2G), from electrocorundum (24A), with a grain size of 40 microns (40-N), on flesh glue (M).

    Application

    • Sandpaper for wood in carpentry is necessary when preparing the surface for painting or varnishing.
    • In construction, sagging on plaster and putty, and wood fibers are cleaned with sandpaper before use. The sandpaper also helps get rid of paint smudges.
    • Car repair: stripping old paint, preparing the surface for puttying, matting the gloss.
    • In the production and repair of furniture and in many other industries.

    Paper-based sandpaper

    This sandpaper has a fairly low wear resistance coefficient. Along with a low safety margin, paper-based emery, as a rule, does not have water-resistant properties.

    P1, P2, PZ… to PI – non-water-resistant paper.

    This greatly narrows the scope of application, but also reduces the market value.

    Fine grain

    Fine-grained abrasive paper is used for:

    • final grinding and polishing of the product;
    • finishing work;
    • polishing with lubricating fluids, etc.

    The small size of the abrasive allows you to remove the smallest dirt and irregularities from the surface. The most convenient processing is at the last stage of manufacturing.

    Types of sandpaper grit: table, markings

    Sandpaper is a two-component material used for surface finishing of various materials. There are a large number of varieties of sandpaper, each of which is designed for specific jobs. Selecting the right sandpaper is considered the key to proper processing of the product.

    Coarse grain

    Coarse sandpaper can be used in the following cases:

    • rust removal and rough surface work;
    • primary sanding of wood;
    • removing the top layer of the applied coating;
    • smoothing out uneven plaster, etc.

    Rough processing is considered the main task of coarse sandpaper.

    What is sandpaper and what is it also called

    Sandpaper is an abrasive crumb of one or another fraction, fixed to a paper or fabric base using special mastics or other adhesives.

    Other names can be found less frequently: sandpaper, sandpaper, sanding paper, sanding paper, etc., but the essence does not change at all.

    Sandpaper. marking. Grit table. let’s decipher Russian GOST and foreign standards

    Sandpaper is an abrasive material applied to a fabric or paper base and is an indispensable assistant for a wide range of home craftsman projects.

    Let’s look at the symbols with which the manufacturer informs us about the types of sandpaper and the permissible areas of its use.

    Sanding paper. grit and classification

    All sanding papers are characterized by several basic parameters by which they are classified:

    • grain size (coarse or fine);
    • type of abrasive application (open or continuous filling);
    • the material from which the base is made (paper, fabric or a combination of materials).

    Closed or continuous fill

    If you need to process any hard material, it is better to use sandpaper with a continuous coating of abrasive. The absence of gaps makes processing more convenient and the sandpaper itself more durable.

    Continuous filling is used for metal parts, as well as polymers or ceramics.

    Semi-open or open fill

    Sandpaper with this type of abrasive application is characterized by the presence of large gaps between the particles. These gaps can take up 50% of the entire surface of the paper. This sandpaper is used for processing soft materials that do not leave behind lumps from the removed layer.

    Half-open or open sandpaper

    The base is half closed. The gaps between the particles cover 40 to 60% of the base area. This abrasive is used for processing soft and friable materials.

    No lumps are formed during operation, which prevents clogging of empty spaces with waste.

    Sandpaper grit

    This parameter of abrasive paper displays the number and size of particles of abrasive substance per unit area, is the main characteristic of the sandpaper and determines the possibility of its use for certain needs.

    Type of abrasive application

    The characteristics of sandpaper also depend on how the abrasive was applied to the substrate. There are two types of application. For different types of processing, one of them will be preferable.

    Base material

    The base is an equally important characteristic that indicates the purpose of the skin. Preferences depend on the purpose of use. The abrasive can be made on three types of material:

    Skin base

    When making sandpaper, abrasive is applied to the base. The base can be made of various materials, the most common of which are paper and fabric.

    Areas of application of abrasive cloths

    Abrasive sandpapers are used in a huge number of different jobs. The main areas of application are divided depending on the grain size of the abrasive.

    Sandpaper with a closed or continuous abrasive layer

    Characterized by complete coverage of the base with abrasive material and is designed for use on hard surfaces.

    How to choose?

    When choosing, you should pay attention not only to the cost, but also to the characteristics of the product.

    What is sandpaper

    Sanding paper is a combination material that consists of: