How many reams of paper are there in a box?

Whiteness

Instrumental determination of the whiteness of materials is a technically complex task. There are too many influencing factors that have technical uncertainty. There is, for example, the problem of maintaining and checking standards, the stability of light sources – they all “age” and it is almost impossible to find two with the same characteristics, there is a problem of the sensitivity of measuring instruments when measuring paper of different colors, etc.

Measurements in the visible part of the spectrum are also affected by invisible, short-wave, ultraviolet radiation. Strictly speaking, to evaluate the optical characteristics of a material, it is necessary to determine its entire reflection spectrum. However, in practice it is more convenient to compare two numbers when comparing samples, which does not allow for comparison of continuous spectra.

  • white

    ( Brightness

    ), as the reflectivity of waves in the range of 457 nm;
  • b

    CIE quality

    ( Whitness

    ), calculated from chromaticity coordinates;
  • CIE lightness

    , defined in chromaticity coordinates L

    , a

    *
    , b

    *
    .

Standard whiteness (Brightness) of paper is the coefficient of diffuse reflection of the surface of the paper when illuminated by a specific light source, measured at a wavelength of 457 nm.

Whiteness is measured by photometers and spectrophotometers. So whiteness is measured according to the standards of different countries and according to the international standard. When measured according to GOST 30113, which coincides with the ISO 2470 standard, whiteness can exceed 100 percent.

When measuring whiteness (as with other color measurements), it is important to specify the lighting source under which the measurements are taken. As a rule, four such sources are used: “A”, “B”, “C”, “D65”. Source “A” reproduces the conditions of average artificial lighting with incandescent electric lamps, “B” – a direct sunlight lamp, “C” – a fluorescent mercury lamp, “D65” – daylight.

Since measurements using this method are carried out in a narrow range of the spectrum (about 457 nm), and the human eye sees the entire spectrum from 400 to 700 nm, the correlation with visual assessment is not always good.

CIE whiteness (Whitness), calculated from chromaticity coordinates and color coordinates (for this, the CIE-Tint value is determined; the value gives an impression of the degree of whiteness of a sample containing OOB and tint dye elements.

Disadvantages of this measurement system: 

  • As an official test, it can only be used to compare samples tested with the same spectrophotometer at the same time. This is due to differences in devices and light sources;
  • The sample to be measured must be sufficiently white. Newsprint, for example, gives erroneous results. The dark blue tint overestimates the CIE whiteness values.

CIE lightness, determined in conjunction with the a* and b* chromaticity coordinates. And represents the difference between black and white. For perfect white L = 100. For perfect black – 0.

As an illustration of the differences in determining the whiteness of paper depending on the method and instruments used, we present slightly processed data from a report given at the Paper Industry Technical Association (PITA) conference in Manchester in October 1997 by A. Tyndall ( Clariant company) “Production and measurement of whiteness”.

Measurements of the same paper sample were made with three spectrophotometers:

  • Elrepho 2000 using a computer program from Clariant;
  • Datacolor Spectraflash 500;
  • Minolta CM-2002

Paper for office equipment Snegurochka (a4, grade c, 80 g/sq.m, 500 sheets) – favorable price – buy the product paper for office equipment Snegurochka (a4, grade c, 80 g/sq.m, 500 sheets) in the Komus online store


wrote on September 16, 2022

It’s hard to remember when my acquaintance with Snegurochka began. Of course, what attracted me first was the design. The paper is really snow-white and pleasant to the touch. When printing, the letters and characters on it do not blur, the image is clear. The manufacturer stated that toner consumption is reduced – I confirm that I have to refill the cartridge less often. The Snow Maiden accompanies me both at work and at home. I have a son, he uses paper in his creativity. It’s easy to draw on. Everyone knows how difficult it is to color pictures with colored pencils, but here the creative process brings real pleasure. The lines lie smoothly, softly, and the results are simply masterpieces. I have been keeping children’s works for several years now. Looking at them, you might think they were made just yesterday. The paper does not yellow at all, the drawings look great. I would like to note the environmental friendliness of the products. I think it is important that the production does not harm the environment. This is very important in the modern world. It is fashionable to list the advantages of the Snow Maiden endlessly and add something new every time. The achievement received – Product of the Year – speaks about its quality.
#I choose the Snow Maiden order 44607532.


wrote on September 15, 2022

Working as a teacher at school, I have to deal with “paperwork” every day.
When choosing paper, I am guided by the most necessary needs for my work: printing assignments, tests, writing something down, or giving paper to children for crafts.
Over the course of a couple of years, I have tried many different brands and types of paper, so I can confidently act as an expert)
My choice fell on paper of the “Snow Maiden” brand, which satisfies all of the above.
“Snegurochka” brand paper meets standards for density and thickness, which ensures stable operation of the printer, without jamming, thereby saving my time and being able to print directly during the lesson.
Since this paper is C grade, it is a budget option for consumables.
And, of course, I am confident in its composition and environmental friendliness, which is important when choosing for children, since it is certified according to FSC and EU Ecolabel environmental standards.
Thus, I do not buy a “pig in a poke”, but choose the time-tested brand “Snegurochka” and recommend it to everyone!


wrote on September 15, 2022

I have been a fan of the “Snow Maiden” paper for several years now.
Mondi has taken paper production in Russia to a completely new level. Paper “Snow Maiden” The A4 sheet format suits me not only for the printer, but also for creating various crafts, such as airplanes, cranes, etc.) I love to create on and from paper.
Therefore, the number of sheets in a pack is very important for me, small packs run out quickly, and in “Snegurochka” there are 500 of them.
Since I don’t strive for premium-class work, I’m quite happy with paper grade C.
Moreover, “Snegurochka” has good indicators: whiteness is 146%, and the brightness of the paper 96% gives a wonderful contrast with black and gray shades. The 91% opacity of the paper allows drawings to be translated well under the influence of bright light and at the same time not to show through under normal conditions.
The international standard for office paper is provided with a density of 80 g/m2, you can safely use it on any printer anywhere in the world and be sure
that she will not get stuck at the most inopportune moment, because… its thickness is only 106 microns.
“Snegurochka” is convenient to order by box; in one box you will receive 5 packs of paper. And most importantly, by purchasing certified products, you receive a guarantee,
that it comes from responsibly managed forests.
“Snegurochka” is certified according to environmental standards FSC and EU Ecolabel and
complies with the national standard of the Russian Federation GOST R 57641-2022. It seems to me
that thanks to this particular standard, my airplanes fly further and longer than others)
#I choose the Snow Maiden
Order number: 44597601


wrote on September 14, 2022

Quite often I have to deal with printing information on paper, for work or school, several times a week my printer is in working mode. For good printing results, not only a good printer is important, but also paper. My choice, more than five years ago, fell on A4 paper “Snegurochka” produced by Mondi Business Paper (the world’s largest manufacturer of paper and pulp products) in Russia, the company is represented by “Mondi Syktyvkar LPK”, which is where “Snegurochka” paper is produced. The technical characteristics of the paper suit my requirements (simple printing and photocopying), the price and availability of purchase are also a factor in my loyalty to the brand. “Snow Maiden” paper is bright, white and smooth, and this is not surprising, because it complies with GOST R 57641-2022. This standard applies to xerographic paper for office equipment (hereinafter referred to as paper), intended for black-and-white and color printing on dot matrix, inkjet, laser, fax machines and copying on duplicating equipment, incl. in double-sided printing mode (duplex), as well as for printing publishing products. In addition, it is certified according to the environmental standards of SC and EU Ecolabel (paper produced without the use of chlorine during the bleaching process of recycled cellulose. I admit that there is an alternative paper that suits my needs, but I choose the Snow Maiden.

В зависимости от формата и плотности

Размер, см
Плотность A4

LA3

La2 50×70 52×72 62×94 64×92 70×100 70×102 72X108 70 4,37

8,73

17,39 24,50 26.21 40,80 41,22 49.00 49,98 54,43 75 4,68

9,36

19,91 26,25 28.08 43,71 44,16 52,50 53,55 58,32 80 4,99

9,98

20,44 28.00 29,95 46,62 47,10 56,00 57,12 62,21 90 5,61

11,23

22,45 31,50 33,70 52,45 52,99 63,00 64,26 69,98 100 6,24

12,47

26,55 35.00 37,44 58,28 58,88 70.00 71,40 77,76 115 7,17

14,35

28,69 40,25 43.06 67,02 67,71 80,50 82,11 89,42 120 7,48

14,97

30,66 42.00 44,93 69,94 70,66 84,00 85,68 93,31 130 8,11

16,22

32,43 45,50 48,67 75,76 76,54 91,00 92,82 101,09 135 8,42

16,84

35,22 47,25 50,54 78,68 79,49 94,50 96,39 104,98 150 9,36

18,71

37,42 52,50 56,16 87,42 88,32 105.00 107,10 116,64 170 10,60

21,21

42,41 59,50 63,65 99,08 100,10 119,00 121,38 132,19 190 11,85

23,70

47,05 66,50 71,14 110,73 111,87 133.00 135,66 147,74 200 12,47

24,95

49,90 70.00 74,88 116,56 117,76 140.00 142,80 155,52 205 12,79

25,57

51,35 71,75 76,75 119,47 120,70 143,50 146,37 159,41 215 1З, 41

26,82

53,05 75,25 80,50 125,30 126,59 150,50 153,51 167,18 220 13,72

27,44

54,65 77.00 82,37 128,22 129,54 154,00 157,08 171,07 225 14,03

28.07

56,32 78,75 84,24 131,13 132,48 157,50 160,65 174,96 235 14,66

29,31

58,07 82,25 87,98 136,96 138,37 164,50 167,79 182,74 240 14,97

29,94

60,44 84,00 89,86 139,87 141,31 168,00 171,36 186,62 250 15,59

31,19

62,38 87,50 93,60 145,70 147,20 175,00 178,50 194,40 255 15,90

31,81

77,90 89,25 95,47 148,61 150,14 178,50 182,07 198,29 270 16,84

33,68

82,49 94,50 101,09 157,36 158,98 189,00 192,78 209,95 275 17.15

34,30

84,01 96,25 102,96 160,27 161,92 192,50 196,35 213,84 285 17,78

35,55

87,07 99,75 106,70 166,10 167,81 199,50 203,49 221,62 300 18,71

37,42

74,84 105.00 112,32 174,84 176,64 210.00 214,20 233,28 315 19,65

39,29

96,23 110,25 117,94 183,58 185,47 220,50 224,91 244,94 320 19,96

39,92

97,76 112.00 119,81 186,50 188,42 224,00 228,48 248,83

350

21,83 43,66 87,32 122,50 131,04 203,98 206,08 245,00 249,90 272,16

375

2Z, Z9 46,78 114,56 131,25 140,40 218,55 220,80 262,50 267,75 291,60

400

24,95 49,90 122,20 140.00 149,76 233,12 235,52 280,00 285,60 311,04

405

25,26 50,52 123,73 141,75 151,63 236,03 238,46 283,50 289,17

314,93

Единицы измерения в 1с – учет в штуках и упаковках

Часто возникает ситуация, когда товар на&nbsp the enterprise receives it in boxes (rolls, etc.), and ships it to customers in pieces (meters); In order to reflect such operations in 1C, you need to create two (and possibly more) units of measurement for the item.

To do this, you need to open the nomenclature card through the “Main Menu” – “Nomenclature Directories” (double-click on it with the mouse or click the “Change” button). This will open the item card:

Справочник Номенклатура

Fig.1.

The main difficulty when creating units of measurement is the need to indicate the conversion factor from the new unit of measurement to the base one.

Please note that postings in the quantity part for accounting and tax accounting are formed in the base unit of measurement.

For example, the base unit of measurement is set to “piece”, and there are also two more units of measurement “packaging” and “box”. The conversion factor for a box is set to 1000, which means that 1 box contains 1000 pieces. And for packaging the conversion factor is 100, i.e. one package contains 100 pieces. In this case, the 1C UPP program is able to freely count not only packages and boxes into pieces, but also packages into boxes; for this, it will calculate the ratio 1000/100 and receive the correct answer that one box contains 10 packages.

Thus, it is recommended to establish the base unit of measurement that will correspond to the minimum possible unit of measurement (or the unit in which balances will be recorded in accounting and tax accounting).

For example, for Paper Ballet it is convenient to select pieces as the base unit. You can change the base unit of measurement in the nomenclature card:

Базовая единица измерения

Fig.2.

After you are convinced that the basic unit of measurement specified in the nomenclature is correct, you need to go to the “Units of Measurement” tab (it may not be completely visible). On the “Units of Measurement” tab there is a list of units of measurement for this item.

Закладка Единицы измерения

Fig.3.

In order to add a new unit of measurement, you must use the “Add” button. A dialog for editing units of measurement will appear. In this dialog, you must select a unit of measurement according to the classifier. In the classifier that opens, select the unit of measurement that you want to add. After selecting the “By classifier” and “Name” fields will be filled in:

Справочник Единицы измерения

Fig.4.

Because in this example, the base unit of measurement is set to “Pieces”, and the added unit of measurement is also “Pieces”, then the conversion factor from “Pieces” to “Pieces” will be equal to one. Therefore, in the “Contains (pieces)” field, you must set the unit.

After the unit of measurement has been set according to the classifier and the conversion factor has been set, the new unit of measurement must be saved by clicking on the “OK” button. A new unit of measurement will appear in the list:

Две единицы измерения

Fig.5.

The unit for storing balances is highlighted in bold (in this unit it will be possible to generate management reports, for example, “Goods in warehouses”).

Since in the example the base unit of measurement was changed from packages to pieces, it is necessary to edit the conversion factor for the “Packages” unit of measurement. To do this, you need to double-click on it with the mouse, or click the “Change” button. In the dialog that opens, in the “Contains (pieces)” field, you need to indicate the number of pieces in one package, this will be the conversion factor:

Пересчет единиц измерения

Fig.6.

For example, the conversion factor is 100.

After finishing changing the units of measurement, the item card must be closed by clicking the “OK” button.

You can check how units of measurement work in any document, for example “Receipt of goods and services”. Let’s create a new document “Receipt of goods and services” and add to it an item for which two units of measurement are set:

Поступление товаров и услуг в доп.единице измерения

Fig.7.

If the unit of measurement is set to “pack”, then the coefficient takes on a value equal to 100. When changing the unit of measurement from packaging to pieces, the coefficient in the document will change its value to 1:

Смена единицы измерения

Fig.8.

When posting a document, the quantity taken into account will be recalculated from the specified units of measurement into units of storage of balances. You can specify the required units of measurement in the “Goods in warehouses” report by clicking on the “Settings” button in the report indicators.

Пересчет количества

Fig.9.

Товары на складах

Fig. 10.

Example with the unit of measure “Boxes”:

Номенклатура в коробках

Fig.11

Поступление в коробках

Fig. 12.

Товары на складах в коробках

Fig. 13.

Do you still have questions about the program? The SITEK company will take care of solving 1C problems: consultations
on work in the program,
improvements
, 1C update
and other services are provided by qualified specialists in the shortest possible time.

___________________________________________________________________________________

Date of article writing 08/10/2022

Number of sheets in a stack, pack

Number of sheets per stack/pack:

The table shows by calculation, depending on the mass of 1 square meter and the paper format, the number of sheets in 1 ton of paper. The accuracy of these data depends on the accuracy of the estimate of the mass of 1 m square of paper and the variations in sheet sizes.

41091.39

30525.03

26397.76

24420.02

16958.35

16650.02

38156.29

28344.67

26455.03

22675.74

20408.16

19078.14

18896.45

15460.73

80

23148.15

22546.9

16693.38

16534.39

90

36370.25

29677.11

20041.69

19065.05

17636.68

14697.24

12247.7

12025.01

26709.4

19841.27

18037.52

15873.02

14285.71

10822.51

120

27277.69

16534.39

15432.1

15031.27

13227.51

11128.92

11022.93

140

23380.87

12883.94

12256.1

9448.224

7873.52

7730.365

20458.27

16693.38

12400.79

10724.09

9920.635

8928.571

6889.33

6764.069

14838.56

11022.93

10288.07

7936.508

7419.278

200

16366.61

9259.259

9018.759

8579.272

6677.35

6613.757

5511.464

5411.255

13929.03

11365.7

7301.508

6754.475

4690.608

4605.324

Number of sheets in 1 ton of paper per paper format (cm)
Weight 1 m 2
paper (g)
47×65 52×72 60×84 60×90 63х88 62×94 70×90 70×100 72×104 70×108 84×108 84×110
60 54555.37 44515.67 33068.78 30864.2 30062.53 28597.57 26455.03 23809.52 22257.83 22045.86 18371.55 18037.52
65 50358.81
28490.03 27750.03

21978.02 20545.69 20350.02

70 46761.75

25767.88

24512.21

15747.04

40916.53 33386.75
24801.59

21448.18 19841.27 17857.14

13778.66 13528.14
22045.86 20576.13
15873.02 14838.56

100

32733.22

18518.52

17158.54

13354.7 13227.51 11022.93

22257.83

14298.79

11904.76

9185.773 9018.759
19078.14 14172.34 13227.51

11337.87 10204.08 9539.072

160
11574.07
11273.45 8346.688
8267.196
180 18185.12
10020.84 9532.525 8818.342

7348.618 6123.849 6012.506

13354.7 9920.635

7936.508

7142.857

235

8443.094 7880.221
7675.54

6079.027 5682.851 5628.729

Useful articles » weight of writing instruments This article provides examples of various postal items and their weight, which are most often used in sending letters (written correspondence) With the help of this article you can calculate the weight of a letter, accurate to hundredths of a gram*.

*Attention! The average weights of items were taken as an example.
Weight deviations between manufacturers may vary, both up and down. The exact weight depends on the material and brand of the product, the manufacturer’s specifications, the measuring device and environmental indicators.

How much does the envelope weigh (without window):

Format Size (mm) Density Weight (grams)
Envelope E65/DL 110×220 80g/m2 4.52 g.
Envelope C5 162×229 80g/m2 6.78 g.
Envelope C4 229×324 90g/m2 14.77 g.
Marked envelope E65/DL with letter A 110×220 90g/m2 4.92 g.
Marked envelope E65/DL with letter D 110×220 90g/m2 4.75 g.

How much does a piece of paper weigh:

Name Format Size (mm) Density Weight (grams)
A5 sheet of paper 148.5×210 80g/m2 2.45 g.
A4 sheet of paper 210×297 80g/m2 4.90 g.
A3 sheet of paper 297×420 80g/m2 9.80 g.
Sheet of notebook paper A5 148.5×210 65g/m2 1.95 g.
Double sheet of A4 notebook paper 210×297 65g/m2 3.91 g.
Sheet of paper “block cube” – 90×90 90×90 80g/m2 0.65 g.

How much does a form, order, invoice and other documents weigh:

Cash receipt order

195×135

1.34 g.

Format Size (mm) Weight (grams)
Cash receipt 44×44 0.14 g.
Cash receipt 80×80 0.29 g.
A6 sales receipt 105×148 0.55 g.
Waybill A5 format 148.5×210 1.32 g.
A5 invoice 148.5×210 1.13 g.
How much does a self-adhesive label weigh:

A4 sheet / Cells per sheet

Size of 1st cell

Weight with backing

Weight without backing

1/1

210×297 mm

8.80 g. 5.60 g.

1/2

210×148 mm

4.40 g.

2.80 g.

1/4 105×148 mm 2.20 g. 1.40 g.

1/8

105×74 mm

1.10 g.

0.70 g.

1/10

105×57 mm

0.88 g. 0.56 g.

1/12

105×48 mm

0.73 g.

0.46 g.

1/18 70×49.5 mm 0.48 g.

0.31 g.

1/21

70×42.3 mm

0.42 g.

0.26 g.

1/21 70×37 mm 0.36 g. 0.23 g.

1/40

48.5×25.4 mm 0.22 g. 0.14 g.

How much does a form, order, invoice and other documents weigh:

Name Size (mm) Weight (grams)
File insert for documents A4 30 microdistrict. 234×305 3.79 g.
File insert for documents A5 30 microdistrict. 215×170 1.95 g.
Sheet of postage stamps with backing 200×304 11.98 g.
One postage stamp with backing 44×29 0.29g.
Branded business card 90×50 1.34 g.
Sticky Note Notes 76×76 0.44 g.
Adhesive bookmark small 12×45 0.03 g.
Large adhesive bookmark 25×45 0.09 g.

How much do fastening elements for documents weigh:

Name Parameters Weight (grams)
Round eyelet D4.8, long. legs 4.6 0.11 g.
Stapler staple No. 24/6 0.04 g.
Stapler staple No. 23/10 0.08 g.
Copper-plated paper clip 28 mm 0.38 g.
Metal paper clip 41 mm 11.9 g.
Metal paper clip 25 mm 4.33 g.
Bank elastic band D60 mm, thickness 1.5 mm 0.62 g.

How many reams of paper are there in a box?

Today I wanted to consider a seemingly simple question: how many packs are there in a box of A4 paper. A4 format is the most common size, widely used in offices of companies, factories and other enterprises. A4 paper is used for printing all kinds of documentation. This is perhaps her main
purpose.

сколько пачек в коробке бумаги А4

A pack of A4 paper may contain a different number of sheets, depending on packaging: 100, 250 or 500 sheets. Accordingly, number of packs
in the box may vary. The most common option is to pack 500 sheets per pack. This is how they are packaged at manufacturing plants. And a smaller number of sheets may already be obtained as a result of repackaging, for retail buyers who do not need large volumes of paper.

Don’t forget about paper weight

. Density can also be called paper thickness; the lower the density, the thinner the pack is, that is, the quantity in the boxes will vary. Standard Density
paper for correct operation of printers is 75-80 g/m 2
.

So we come close to the question of interest. Packs of 500 sheets and density 80 – 70 g/m 2
(as we have already found out, the most common characteristics) are sealed in boxes of five pieces
.

пачка бумаги А3

If we take other characteristics: at paper density 60

g/m 2
and a quantity of 500 sheets, six pieces are packed in boxes. Packs of 100 sheets are packed in quantities of 10 units per box. Such boxes are most often used for colored paper, mixes, Pastel and Supermix. Due to their high cost

, the number of sheets is reduced to one hundred or 250 pcs. in a pack and can mix several colors in each at once. This packaging turns out to be more convenient
and beneficial for the final retail buyer.

By the way, packs of A3 paper are also packaged mainly five pieces in one box. And the A5 format (half the size of A4) is sealed in boxes identical in size to the A4 format, but ten units each. I think it’s now very clear to you how many packs of paper one box contains.

Structure and properties of paper

The correct choice of paper according to its properties allows you to obtain the required quality of a specific printing product. The first indicator is the mass of one square meter (g/m2). According to the accepted classification, the weight of 1 m2 of printed paper can range from 40 to 250 grams.

Geometric:

smoothness, thickness and weight of 1 m2, density and porosity; Optical: optical brightness, opacity, gloss; Mechanical (strength and deformation): surface strength to plucking, breaking length or tensile strength, fracture strength, tear resistance , delamination resistance, rigidity, compressive elasticity, etc. Sorptive: wet strength, hydrophobicity, ability to absorb printing ink solvents.

All these indicators are closely dependent on each other. The degree of their influence on the assessment of the printing properties of paper is different for different printing methods.

Paper is often classified according to its surface finish. This can be unfinished paper – matte, machine-smooth paper and glazed (aka calendered) paper, which is further processed in supercalenders to give it high density and smoothness.

Geometric properties of paper

Smoothness

of paper, that is, the microrelief, the microgeometry of its surface determines the “resolution” of the paper: its ability to transmit the finest colorful lines, dots and their combinations without breaks or distortions. This is one of the most important printing properties of paper.

The higher the smoothness of the paper, the greater the completeness of contact between its surface and the printing plate, the less pressure needs to be applied when printing, the higher the image quality. The smoothness of paper is determined in seconds using pneumatic instruments or using profilograms, which give a visual representation of the nature of the paper surface.

Different printing methods place different smoothness requirements on paper. Thus, calendered printing paper should have a smoothness of 100 to 250 seconds, while offset paper of the same degree of finishing can have a smoothness much lower – 80-150 seconds.

Gravure printing paper has an increased smoothness, which ranges from 300 to 700 sec. Newsprint cannot be smooth due to its high porosity. The application of any coating layer significantly improves the smoothness of the surface – be it surface sizing, pigmentation, light or simple coating, which, in turn, can be different: one-sided and two-sided, single and multiple, etc.

Surface sizing is the application of a thin layer of sizing agents to the surface of the paper (coating weight is up to 6 g/m2 in order to ensure high strength of the paper surface, protecting it from plucking out individual fibers with sticky paints, as well as to reduce paper deformation when moistened to ensure accurate ink matches during multi-color printing, especially important for offset and lithographic printing, where the paper is wetted with water during the printing process.

Pigmentation and paper coating differ only in the mass of the applied coating. Thus, it is believed that the weight of the coating layer in pigmented papers does not exceed 14 g/m2, and in coated papers reaches 40 g/m2. The chalk layer is characterized by a high degree of whiteness and smoothness.

High smoothness is one of the most important characteristics of coated papers. Their smoothness reaches 1000 seconds. or more, and the relief height does not exceed 1 micron. The smoothness index not only ensures optimal interaction between paper and paint, but also improves the optical properties of the surface that perceives the colorful image. The high smoothness of coated paper allows printing with good imprinting at small thicknesses of the ink layer.

The reciprocal of smoothness is roughness

, which is measured in micrometers. It directly characterizes the microrelief of the paper surface. As a rule, paper technical specifications indicate one of these two values.

An important geometric characteristic of paper, along with the thickness and weight of 1 m2, is bulk

. It characterizes the degree of paper compaction and is very closely related to such optical characteristics as opacity. That is, the fluffier the paper, the more opaque it is at the same grammage. Plumpness is measured in cm3/g. The bulk of printed papers ranges, on average, from 2 cm3/g (for loose, porous papers) to 0.73 cm3/g (for high-density calendered papers).

{In practical application, this means that if you take a plumper paper of a smaller grammage, then at the same opacity, there will be more sheets in a ton of paper}

Porosity

directly affects the absorbency of the paper, that is, its ability to accept printing ink and may well serve as a characteristic of the structure of the paper. Paper is a porous-capillary material, and a distinction is made between macro- and microporosity.

Macropores, or simply pores, are spaces between fibers filled with air and moisture. Micropores, or capillaries, are tiny spaces of indefinite shape that penetrate the outer layer of coated papers, as well as those formed between filler particles or between them and the walls of cellulose fibers in uncoated papers.

There are also capillaries inside cellulose fibers. All uncoated, not too compacted papers, such as newsprint, are macroporous. The total pore volume in such papers reaches 60% or more, and the average pore radius is about 0.16-0.18 microns. Such papers absorb paint well due to their loose structure, that is, a highly developed inner surface.

Coated papers are microporous, otherwise capillary papers. They also absorb paint well, but under the influence of capillary pressure forces. Here the porosity is only 30%, and the pore size does not exceed 0.03 microns. The remaining papers occupy an intermediate position.

{In fact, this means that when printing on offset paper, both the solvents contained in the paint and the color pigments penetrate into the pores. Thus, the concentration of pigment on the surface is low and it is impossible to achieve rich colors.

Optical properties of paper

A special place in the structure of the printing properties of paper is occupied by optical properties, that is, whiteness, opacity, gloss (gloss).

Optical brightness

is the ability of paper to reflect light diffusely and evenly in all directions. High optical brightness for printed papers is highly desirable, since the clarity and readability of the publication depends on the contrast of the printed and white areas of the print.

With multicolor printing, the color accuracy of the image and its correspondence to the original are possible only when printing on sufficiently white paper. To increase optical brightness, expensive high-quality papers add so-called optical brighteners – phosphors, as well as blue and violet dyes, which eliminate the yellowish tint inherent in cellulose fibers.

This technological technique is called tinting. Thus, coated papers without optical brightener have an optical brightness of at least 76%, and with optical brightener – at least 84%. Printed papers containing wood pulp must have an optical brightness of at least 72%, but newsprint may not be white enough. Its optical brightness averages 65%.

Another important practical property of printed paper is its opacity

. Opacity is especially important when printing on both sides. To increase opacity, a composition of fibrous materials is selected, the degree of grinding is combined, and fillers are introduced.

The optical properties of paper also include its gloss

or glossy. Gloss, or gloss, is the result of the mirror reflection of the light falling on it by the surface of the paper. Naturally, this is closely related to the microgeometry of the surface, that is, to the smoothness of the paper. Typically, as smoothness increases, gloss also increases.

Most consumers of printed materials prefer glossy papers, but gloss is not always needed in publications. Thus, when reproducing text or line illustrations, paper with minimal gloss is used, for example, machine-smooth paper. And various brochures, labels, and reproductions of paintings look great on high-gloss paper.

Mechanical properties of paper

The next group of printing properties is the mechanical properties of paper, which can be divided into strength and deformation. Deformation properties manifest themselves when the material is exposed to external forces and are characterized by a temporary or permanent change in the shape or volume of the body.

Basic technological operations of printing are accompanied by significant deformation of paper, for example: stretching, compression, bending. The normal (uninterrupted) flow of technological processes of printing and subsequent processing of printed products depends on how the paper behaves under these influences.

Softness

of paper is related to its structure, that is, its density and porosity. So, large-pored newsprint can be deformed under compression up to 28%, and for thick coated paper the compressive deformation does not exceed 6-8%. For letterpress printing, it is important that these deformations are completely reversible, so that after the load is removed, the paper completely restores its original shape.

Otherwise, traces of reverse relief are visible on the print, indicating that serious changes have occurred in the structure of the paper. If the paper is intended for embossing, then the goal, on the contrary, is residual deformation, and the indicator of quality is its irreversibility, that is, the stability of the embossing relief.

For offset printing on high-speed rotary machines, the strength characteristics of the paper are very important, namely: tensile strength, fracture strength, resistance to plucking, and moisture resistance. Durability

of paper depends not on the strength of individual components, but on the strength of the paper structure itself, which is formed during the papermaking process. This property is usually characterized by breaking length in meters or breaking force in newtons. So for softer printing papers, the breaking length is at least 2500 m, and for hard offset papers, this value increases to 3500 m or more.

Papers intended for flat-sheet printing should have minimal distortion when wet

, since according to the conditions of the printing process technology, they come into contact with moistened surfaces. Paper is a hygroscopic material. With increasing humidity, its fibers swell and expand, mainly in diameter; the paper loses its shape, warps and wrinkles, and when dried, the reverse process occurs: the paper shrinks, as a result of which the format changes.

High humidity sharply reduces the mechanical tensile strength of paper; the paper cannot withstand high printing speeds and breaks. Changes in paper humidity during multicolor printing lead to ink misregistration and color rendition problems.

To increase moisture resistance

During production, hydrophobic substances are added to the composition of the paper pulp (this operation is called sizing in the pulp) or sizing agents are applied to the surface of the finished paper (surface sizing). Offset papers are highly sized, and especially those that, during use, are subject to sudden changes in climatic conditions or are sealed in many ink runs, for example, cartographic papers.

Sorption properties of paper

Finally, we come close to one of the most important properties of printed paper – its absorbency. Correct assessment of absorbency means meeting the conditions for timely and complete fixation of paint and, as a result, obtaining a high-quality print.

Absorbency

paper, primarily depends on its structure, since the processes of interaction between paper and printing ink are fundamentally different. Before talking about the features of this interaction in certain cases, it is necessary to once again recall the main types of structures of modern printed papers.

If we depict the structure of paper in the form of a scale, then at one of its ends there will be macroporous papers consisting entirely of wood pulp, for example, newspaper. The other end of the scale, accordingly, will be occupied by pure cellulose microporous papers, for example, coated ones.

Macroporous papers accept paint well, absorbing it as a whole. The paints here are low viscosity. Liquid paint quickly fills large pores, absorbing to a sufficiently large depth. Moreover, its excessive absorption can even cause “piercing” of the print, that is, the image becomes visible from the defensive side of the sheet.

Increased macroporosity of paper is undesirable, for example, in illustration printing, when excessive absorption leads to loss of saturation and glossiness of the paint. Microporous (capillary) papers are characterized by the mechanism of the so-called “selective absorption”, when, under the action of capillary pressure forces, predominantly a low-viscosity ink component (solvent) is absorbed into the micropores of the surface layer of the paper, and the pigment and film former remain on the surface of the paper.