Storage of Documents as a Function of Sustainability

Abstract

Sustainability is a premise that has been implemented in all technologies, industries, and service activities to have as little impact on the environment as possible. Typography as a profession made its contribution by creating eco fonts. In each country, the law regulates the lifespan of the storage of everyday business documents. One of the ways to reduce the impact on the environment is to reduce the consumption of ink, which can be achieved by printing the document with more sustainable fonts. By using the mentioned fonts when creating documents, the user should not notice a visual difference, and the document should have the same level of readability. Earlier research on ecological standards was only related to the environmental acceptability of materials, i.e., inks or printing substrates. Using eco fonts, each ink can have a reduced environmental impact. The more environmentally friendly fonts, Ryman Eco and Ecofont Sans, were tested in this experiment. Arial as a standard sans serif font and Times New Roman as a standard serif font were used as reference fonts. In the research, coverage data of different document samples created with different types of typeface and spacing are interpreted to investigate the possibility of saving ink. As eco fonts have been used since the end of the previous and beginning of this century, some stored documents are certainly ready for waste management, which is almost always recycled. By recycling document samples, the optical characteristics of laboratory paper sheets obtained by chemical deinking flotation were investigated. Another aim of the investigation is to provide insight into the quality of recycled fibres after the recycling process.

1. Introduction

Most documents are only stored for a short time, but some may need to be kept permanently. The storage time of a document or file may be determined by the legal framework or business entity. Important state documents or files are kept in the state or business archives, and the others eventually undergo the cutting process to preserve the secrecy of the information they contain. The valuable raw material thus obtained, paper, is involved in the recycling process. The paper recycling process ensures circular management of resources, from cradle to cradle, which contributes to increasing the sustainability of business processes [1,2].

Energy consumption contributes to the greenhouse effect, and the paper industry accounts for approximately 6% of the total industrial energy consumption and 2% of direct CO₂ emissions of all industries [3]. The production of recycled paper uses fewer resources, such as energy (28–70%) and water, and reduces the emission of carbon dioxide and wastewater compared to paper made from virgin fibres [4]. The deinking process is based on the separation of ink particles from cellulose fibres and paper suspension. The effectiveness depends on the technique and conditions in printing, the type of ink and printing substrate, the age and environmental conditions of the print, and other factors [5,6]. Impurities in the paper pulp can include particles of ink, additives in paper making, fillers, bleaches, and short cellulose fibres. There are various deinking methods, and the most common one is chemical deinking flotation, which usually uses chemicals such as peroxides, caustic soda, and surface-active substances that can contribute to water pollution, but to a lesser extent than when creating paper from virgin fibres. Alternative deinking procedures can be enzymatic or ultrasonic, but their efficiency is not always high [7,8]. In addition, excessive use of cellulases and hemicellulases can cause depolymerization, which leads to the extrication of quality cellulose fibres that could still be used and high BOD in wastewater (Biochemical oxygen demand) [6]. The low efficiency and high cost of the wastewater treatment process can indicate low economic profitability.

Recognizing paper recycling methods as a sustainable raw material source, the environmental friendliness of documents and files can be increased by the thoughtful use of fonts [9]. Typographical elements, design, and font size can contribute to lower ink consumption, and not using big spacing between lines can contribute to reduced paper consumption [10]. By studying the life cycle of the product it can be concluded that lower consumption of ink will contribute to lower consumption of raw materials and less pollution of air, water, and soil in the phase production of the inks, and low-er coverage of prints will reduce the amount of separate ink particles and additives in phase deinking flotation [11].

The ink for the printer consists of resin, pigments, and additives. In the process of printing, nano-sized particles (semi-volatile organic compounds), volatile organic compounds (styrene, benzene, chlorobenzene, toluene, ethylbenzenes, styrene, xylenes), gases (nitrogen dioxide, sulphur dioxide, carbon monoxide), metals (lead, nickel, arsenic, iron, zinc, titanium, chromium, nickel, manganese), benzene, ammonia, and ink particles are emitted into the air [12,13,14]. From the above, it is evident that the emissions have a global effect on the environment through the greenhouse effect due to CO₂ emissions, as well as a local effect through acid rain (NO₂ and SO₂), winter smog (SO₂), and photochemical smog (VOC and NO₂) [15,16,17,18]. In addition to locally affecting the air, it also affects water pollution due to the effects of metals and ammonia. Ammonia in aquatic organisms can cause altered behaviour and differences in swimming and feeding activity due to oxidative stress. Aquatic organisms have a lower capacity for antioxidant defence, which can cause increased oxidative tissue damage [19]. Metals in the water medium often settle to the bottom, where they often remain for a long time and influence reactions in the sediment. Bottom sediments provide a food source for benthic fauna and minerals for benthic flora; therefore, metals are directly or indirectly toxic to the aquatic fauna and flora [20,21]. Aquatic organisms, through the process of biomagnification, enable the transition of metals into an organic form that is more harmful to living organisms, or it can be concentrated through the food chain of aquatic organisms, which can potentially impact human health [22]. Human health is affected by high levels of nanoparticles (PM_0.1) in the working environment. The harmfulness is caused by their small size, which enables them to enter the bronchi and smaller bronchioles and cause respiratory diseases [23,24]. The impact of floating particles on the nervous and cardiovascular systems is seldom mentioned, but it is significant [25]. Floating particles of the mentioned sizes contain organic and elemental carbon, and metals including iron, zinc, titanium, chromium, nickel, and manganese. In the working environment, VOC compounds are a safety risk and health hazard and can be associated with respiratory and cancerous diseases [26,27]. Carbon monoxide in the human body instantly reacts with haemoglobin to form carboxyhaemoglobin, reducing the ability of oxygen to bind to haemoglobin [17].

When creating a document, sustainability can be increased by using special fonts—ecofonts—which reduce the consumption of toner or ink. In this way, the emissions into the air and the use of materials, soil, and water are directly reduced [28]. The Ryman Eco font is characterized by semi-hollow letters, constructed with very thin lines so that the ink consumption is reduced to 33% of the consumption of standard fonts. Ecofont Sans features small hole letters, and by using the Ecofonts software, small holes can be punched in standard fonts such as Arial, Calibri, Verdana, Times New Roman, and Trebuchet MS, which can reduce ink consumption by up to 50%.

The aim of the work is to characterize the optical properties of recycled laboratory paper sheets made from unaged and aged prints printed with different standard and eco fonts using variable spacing. Increasing the distance between the lines will contribute to better readability, higher paper consumption, and better raw material quality (fewer ink particles in the paper pulp). By linking the results of the coverage of print sheets and ink consumption with the optical properties of recycled laboratory sheets, it is possible to recommend the use of a specific typeface, font size, and spacing to contribute to increasing the quality of the paper pulp while saving ink.

2. Methods

The standard black and white document is created, which contains standard elements (Figure 1). The designed printing forms are created with two standard fonts: Arial and Times New Roman. Arial is a standard sans serif typeface and Times New Roman is a standard serif typeface, which is commonly used in newspapers because it has good readability at a small size. The printing forms were designed with different sizes of fonts (8, 10, and 12) and different spacing (8, 10, 12, and 14). Figure 2 shows the flow diagram of the experiment.

Some of the prints were subjected to an accelerated ageing process in the Solarbox 1500e chamber, Cofomegra. The conditions in the chamber roughly correspond to the natural ageing of samples in an office space for three years. The condition in the chamber was as follows: filtered xenon light with the indoor filter and a BST temperature of 60 °C, at irradiation of 550 W/m².

Aged and unaged prints were manually torn into 2 × 2 cm pieces and placed in a Hobart-type pulper with chemicals according to the INGEDE 11 standard method [29]. The chemicals used are sodium hydroxide (0.6%), sodium silicate (1.8%), hydrogen peroxide (0.7%), and oleic acid (0.8%). Handsheets were made before the flotation procedure according to the standard INGEDE 1 [6] procedures and ISO 5269-2:2004 [30] on a device for the automatic production of laboratory paper sheets, the Rapid Köthen sheet former. The paper pulp was transferred to the flotation unit according to INGEDE 11. Laboratory handsheets were made after the deinking flotation process. The following methods for measuring the optical characteristics of laboratory handsheets were then used: the relative reflectance, the image analysis, and the ERIC number.

The list of unaged and aged samples before and after the deinking flotation process is provided in

Table 1. The list of samples and their marks.

Size of Font	Space	Unaged		Aged
		Before Flotation	After Flotation	Before Flotation	After Flotation
8	8	F8S8 BF	F8S8 AF	AF8S8 BF	AF8S8 AF
	10	F8S10 BF	F8S10 AF	AF8S10 BF	AF8S10 AF
10	10	F10S10 BF	F10S10 AF	AF10S10 BF	AF10S10 AF
	12	F10S12 BF	F10S12 AF	AF10S12 BF	AF10S12 AF
12	12	F12S12 BF	F12S12 AF	AF12S12 BF	AF12S12 AF
	14	F12S14 BF	F12S14 AF	AF12S14 BF	AF12S14 AF

. The space and font size of the samples are shown in the list.

The Reflectance spectra values (R) were measured on all laboratory handsheets using a spectrophotometer X-rite. Device settings were as follows: a standard illuminant D65 and a two-degree standard observer, and the interval of the wavelengths was from 390 to 700 nm for every 10 nm. The relative reflectance changes (∆R) were calculated from values of reflectance spectra values for unaged laboratory handsheets (R_unaged) and from values of reflectance spectra values after the process accelerated ageing laboratory handsheets (R_aged) according to Equation (1).

∆R = R_unaged − R_aged

(1)

The effective residual ink concentration (ERIC number) was measured on laboratory handsheets before and after deinking flotation. The ERIC method measures reflectance in the spectrum’s IR region where the ink’s light absorption coefficient is several orders of magnitude greater than the absorption coefficient of the fibre and other components. They were analysed using a spectrophotometer Technidyne Color Touch 2. The spectrophotometer for pulp and paper has six colour scales and three light sources. Samples were measured according to standard methods ISO 22754:2008 [31].

The image analysis was carried out according to ISO 13322-1, 2014 [32]. The image analysis detected a count of the residual dirt particles and area. For analysis, the Spec*Scan Apogee System image analysis software was used, which uses a scanner to digitize an image. The device was set to the following values: threshold value (100), white level (75), and black level (65) were chosen after comparing the computer images to the handsheets. Optical properties were determined with laboratory sheets of paper: relative reflectance and image analysis. The samples were measured in five different places and the average was calculated.

Using the program Inkfarm, the cover surfaces of printing forms were determined concerning the size and type of font [33]. The coverage factor for the fonts Ecofont Vera Sans, Times New Roman, Arial, Times New Roman bold, and Arial bold was analysed for font sizes 9, 10, 11, 12, 24, 36, and 42. Since there were no data for font size 8, the data were calculated by the Lagrangian form of the interpolation polynomial from font sizes 9, 10, 11, 12, 24, 36, and 42. The mentioned program was used to analyse the coverage of the printed form which consists only of letters, characters, and tables. In the above-mentioned way, it is possible to determine the share of the covered surfaces of the printing form, which are in direct correlation with the consumption of ink in the printing process of a certain printing form.

The Fill ink coverage calculator program was used to determine the coverage of the printed form [34]. This program can determine coverage, whether it is letters and characters or images, tables, or other elements. The program analyses print forms for all combinations of font types and sizes, as well as line spacing. The coverage of the printing form is determined concerning ten classes of greyscale points of the printing form (classes of the area from ˂10 to 90–100, in scale increments of 10). The data are calculated for black and white printing of the document form.

3. Results and Discussion

Significant settings that are in the domain of ecological sustainability and circular production are the recycling of used products. Figure 3 shows dirt specks in different size categories as a parameter of the quality of a laboratory sheet made from recycled fibres as a simulation of disposal documents when they no longer have their function.

The research results show that the ageing of the F8S8 Arial print in the size class 0.001–0.006 mm² increases the count of dirt specks compared to the unaged print by 19.3% on the handsheet from fibre before flotation (Figure 3a). After flotation of the unaged sample, the dirt count is reduced by 67% and the aged prints reduce the dirt count by 30.8%. In this case, the results indicate a somewhat lower efficiency of the flotation of the aged prints, probably caused by an increase in the number of very small particles created by the ageing process, which are more difficult to separate in the flotation process.

By recycling the unaged print F8S8, the total coverage of the laboratory paper sheets’ surface with dirt specks for all observed size classes is very similar (unaged prints 0.14 mm², aged prints 0.15 mm²). However, if we look at the size class 0.001–0.006 mm², the coverage area is larger for the aged prints (0.14 mm²) compared to the unaged prints (0.11 mm²).

Sample F8S10 (Figure 3b) differs from F8S8 by containing a smaller number of dirt specks on the laboratory paper sheets, both unaged ones before flotation (F8S10BF dirt specks count is 30; F8S8BF dirt specks count is 42), as well as those after flotation (F8S10BF dirt specks count is 17; F8SBF dirt specks count is 17; F8S8BF dirt specks count is 14) for the class size 0.001–0.006 mm².

The efficiency of dirt speck removal by recycling for the unaged prints F8S10AF is 56.7%, and for the aged AFS10AF it is 37.2%. Similar results are present when observing the coverage of the laboratory paper sheets’ surface with dirt specks. For the AF8S10 AF sample, the coverage area is reduced by 57%.

The results in Figure 4b show that all dirt specks for samples F10S12 are classified in the lowest size class of 0.001–0.006 mm² in contrast to F10S10 (Figure 4a). The behaviour demonstrated by sample F10S12 can probably be explained by a larger space between the lines of text. When the efficiency of separation is studied, the success rate is higher in non-aged samples, but the numerical value of separated particles is almost the same in non-aged and aged samples. Impurity particles that merge into size classes larger than 0.06 mm² have a higher separation efficiency, and they are probably large enough to connect to the foam bubble in the flotation process.

The surface coverage with dirt specks is the same in the unaged and aged samples before the deinking flotation process. In the case of sample F10S12 (Figure 4b), the flotation process completely removes dirt specks from the classes 0.013–0.02 mm² and 0.021–0.03 mm², while for the aged sample AF10 S12AF from the class 0.013–0.02 mm².

Most Arial unaged and aged samples before flotation have the trend that increasing the font size and the spacing decreases the number of dirt particles in the lowest size class particle size (0.01–0.06 mm²) (Figure 3, Figure 4 and Figure 5a). The exception to this trend is the unaged and aged samples of laboratory sheets F12S14 and AF12S14 (Figure 5b). This exception could be explained by the reduction of the number of particles of higher classes, which affects the increase in the number of particles in the size class of 0.01–0.06 mm².

The results of the research by Times New Roman show that for the samples F8S8BF and F8S10BF, the dirt speck counts on the laboratory sheet are distributed in the two smallest size classes: 0.001–0.006 mm² and 0.006–0.013 mm² (Figure 6a,b). The laboratory sheet obtained from the sample of Arial F8S8BF has 3.4% more dirt specks than the Times New Roman F8S8BF laboratory sheet. However, sample F8S8BFA has 48.2% fewer dirt specks on laboratory paper sheets compared to F8S8AF Arial. The sample F8S8AF Times New Roman has 54.3% less dirt specks compared to the one before flotation, and for the aged print, this size is 38.0%. These data offer a direct insight into the good efficiency of the flotation process.

The research results show that in all experimental combinations for samples F10S10, in contrast to samples F10S12, dirt specks are distributed in several classes (Figure 7a,b). Laboratory sheet F10S10BF Times New Roman contains 12.5% more dirt specks compared to F10S10BF Arial, while sheet F10S12BF Arial contains 16.7% more dirt specks compared to F10S12BF Times Nev Roman.

Laboratory sheet F12S12BF Times New Roman in class 0.001–0.006 mm² contains 56.0% more dirt specks compared to F12S12 BF Arial, while samples F12S1 4BF New Roman Times contain 13.6% more dirt specks compared to F12S14BF Arial (Figure 8a,b). The described trend refers to the fragmentation of impurity particles after the production of sheets of paper from the Times New Roman typeface pattern into particles of the smallest sizes. In contrast, the Arial samples have particles of impurities in classes of larger sizes, which contribute to covering a larger total surface with particles of impurities on laboratory paper sheets.

Comparing the Ryman Eco typeface with the Arial and Times New Roman typefaces, the number of dirt particles is smaller for Ryman Eco for aged and non-aged samples for spacing sizes 8 and 10 (Figure 9). The reason for such results can be found in the typeface design. On the other hand, when creating a document, attention must be paid to the readability of a text written in a small font size, especially for people with dyslexia.

The distribution of dirt particles for the typeface Ryman Eco on laboratory sheets for font size 10 is in the two smallest classes. The efficiency of the deinking flotation process is high, with a rate of successful separation particles of about 50% (Figure 10). Success is higher for samples with bigger spacing. Such data may point to the desirability of choosing this typeface and font size to obtain good quality raw material.

Figure 11a,b show the results obtained for font size 12, and both figures show the lowest number of dirt particles. Such results can be explained by the fact that increasing the font size increases the space of semi-hollow letters, built with very thin lines. Larger cavities in the letters contribute to the fragmentation of impurity particles only in the smallest class size of 0.01–0.06 mm², and the surface of the formed impurity particles does not significantly affect the greyness of the obtained sheet. Font size 12 allows for good readability.

Comparing Ecofont Vera Sans with Arial, which did not have small holes punched in the typeface, the number of impurity particles is less than before deinking flotation (15%) in the class of particles up to 0.006mm². The aged sample Ecofont Vera Sans in the class of particles up to 0.006mm² after deinking flotation has 25% fewer dirt particles (Figure 12). The number of dirt particles for samples Ecofont Vera Sans is fewer than for samples Times New Roman.

The recycling efficiency of the Ecofont Vera Sans typeface is the highest with sample F10S12 (Figure 13b). It can be assumed that with this font size and spacing in the deinking flotation process, the optimal fragmentation of dye particles occurs. The separation of dye particles is also influenced by the geometry of the particles, which is influenced by the typeface design—in this case, small holes punched in the typeface.

For Ecofont Vera Sans, the smallest number of particles is for samples F12S12 and F12S14 (Figure 14a,b). The samples have dirt particles that are classified as particles smaller than 0.006 mm². From the results, it could be concluded that the paper pulp will be of good quality.

Effective residual ink concentration for typeface Arial has higher ERIC number values of about 10% for samples before flotation and about 20% for samples after flotation than Times New Roman (Figure 15). For samples printed with Arial, a larger number of ink particles before the flotation process causes a larger number of small ink particles after flotation, which often merges into smaller particle size classes 0.01–0.06mm² (Image analysis, Figure 3, Figure 4 and Figure 5). Particles of the mentioned sizes are difficult to separate from the paper pulp, which causes the greyness of the laboratory sheet samples, respectively, a higher ERIC number value. As the sample aged, fragmentation of the dye particles occurs and the number of particles in the particle size classes smaller than 0.06mm² increases, which increases the ERIC number and additionally contributes to the greyness of the laboratory paper sheet (Figure 15).

The efficiency of recycling can be monitored using the relative reflection of sheets made of fibres from different stages of the recycling process, which can also serve as a method of proof and confirmation of the results presented so far. In general, the reflectance values of the spectral curves indicate the optical properties of the sheets during the entire measurement range of wavelengths. In Figure 16 and Figure 17, the curves of relative reflection are shown, and the results show that the reflective properties before flotation are lower in the entire range of wavelengths from about 400 to 430 nm. On the curves, one can notice an increased reflection in the range of wavelengths of the violet-blue part of the spectrum, which is caused by the addition of optical bleach. In the case of samples printed with Arial typeface, there is a much faster trend of decreasing relative reflectance values in the range from 390 nm to 690 nm (from blue, green, to yellow under visible light) (Figure 16).

The recycled paper contains significantly more impurities and fewer fibres, which increases the amount of scattered and absorbed rays of light. The reflection for newsprint is around 0.6, while for papers that contain optical brightening agents, it is between 0.7 and 0.8. In this case, the reflection is 0.9, which is what the lightest papers have. The reflectance curves for samples printed with Times New Roman do not have a large ΔR between samples before and after deinking flotation for both unaged and aged samples (Figure 17). The reasons for such trends can be found in the small number of ink particles on the samples, which is proven by image analysis and ERIC number. Although the image analysis determined that the paint particles are in the class below 0.4 mm², which affects the greyness of the paper, there are not enough of them to have a significant effect on the outside relative reflection.

Figure 18 shows the influence of the font size on the coverage factor for the fonts Ecofont Vera Sans, Times New Roman, Arial, Times New Roman bold, and Arial bold for font sizes 8, 10, and 12. It is interesting to note that Arial and Times New Roman bold have the same coverage factor values for all font sizes. In contrast, bold Arial has about 30% more coverage than Times New Roman bold typeface, depending on the font size. Times New Roman regular has about 29%, and Ecofont Vera Sans has about 24% less coverage factor than the Arial regular font. According to the determination of the coverage factor, Times New Roman was the most suitable typeface for recycling if other elements such as spacing between lines, tables, images, and other elements are not studied, which will be covered in the continuation of the research.

The program Fill ink coverage calculator determines the greyscale points for all printed forms containing letters, symbols, and a table. The results are presented in 10 classes area describing the saturation of printed forms designed with a certain typeface. The greyscale values for the Ryman Eco and Ecofont Vera Sans fonts in the class area <10% are 82% and 65% higher than the class area 90–100%. The obtained results can be explained by the fact that eco fonts do not have a filled surface of typographic elements on the printed form (Figure 19).

The same trend is followed by the Times New Roman typeface as a representative of serif fonts, which does not have solid flat surfaces in the design of the letters, but the design elements are intersected by strokes that protrude from the main stroke letters [35] (Figure 19). By studying the bold fonts in middle-class areas from 10 to 20 to 40 to 50, it can be noticed that there is no significant difference compared to regular fonts in the greyscale value. Bold fonts have major greyscale contributions in the 80–90 and 90–100 area classes. It is important to know which surface classes of bold fonts will not affect the greyscale value due to increasing the efficiency of the recycling process. When comparing bold letters with regular letters in the 90–100 grade range, an increase in grey values can be observed. The increase for Times New Roman is 24%, while for Arial it is 21%. The values can be explained by the smooth design of Arial letters and characters, which are not affected as much by bolding.

4. Conclusions

Most documents are stored for a short number of years, from three to five years. The storage period is determined by state laws, regulations, or determined by business entities. By digitizing the administration, additional documents do not require storage. Documents or office paper is a highly valuable raw material for making recycled paper because it is homogeneous, easy to collect, and recyclable. The obtained raw material does not have to be bleached and can be recycled without the use of chemicals [36,37].

To additionally increase the efficiency of the deinking process and sustainability of the printing process, during writing a document one can pay attention to the typeface used, as well as the size of the letters and the line spacing. The use of eco fonts can also reduce the use of paint and the impact on the environment by reducing the use of raw materials to produce dyes, reducing emissions during printing, and by following sustainable recycling procedures.

The research shows the results of the chemical deinking flotation of two standard typefaces and two eco typefaces. The design of the letters and characters significantly affects the quality of the recycled paper. The results of the image analysis indicate that before and after the deinking flotation procedure, there are particles in the size classes up to 0.4 mm² on the laboratory paper, regardless of the used typeface, font size, and spacing. These classes of particle sizes affect the greyness of the paper and prove that there is no inhomogeneity on the paper. Recycled paper sheets printed with Times New Roman and eco typefaces have a lower particle count and coverage. Relative reflection curves and low ERIC number values also speak for this. The obtained results show that the obtained recycled laboratory sheets are of good quality.

The results showed that Times New Roman and eco typefaces have a smaller coverage factor from all font sizes and smaller greyscale points in class areas from 10 to 100, and the results of optical properties are consistent with these results. It should be noted that Arial has a proportionally larger x-height than Times New Roman. Such proportions enable Arial better readability in a smaller text size of 10 points [35]. Smaller font sizes can contribute to the reduction of ink consumption, and also to the higher quality of cellulose pulp after the deinking flotation process. When studying the standard fonts, Times New Roman will give a higher quality paper pulp. Using larger spacing in the text will consume a larger amount of printing paper, but better optical properties are visible on recycled laboratory sheets (F10S12 and F12S14). Using font size 10 and spacing 10 enables good readability and less paper consumption, and quality paper pulp would be obtained. Sustainable documents are the way to a more sustainable future. The paper industry could face a limitation in the availability of resources, which was noticeable during the COVID-19 pandemic. Recycling is proposed as a sustainable solution to the listed problems and office paper is a source of quality raw material.