GB/T 4688-2002 Analysis of fiber composition of paper, paperboard and pulp
Some standard content:
GB/T4688-2002
This standard is a revision of (GB/T46881984 "Determination of fiber composition of paper and paperboard". This standard is equivalent to IS 9184-1:1990, IS0 9184-2:199, JSO 9184-3;1990, [SO 9184 4:1990IS09184-5:1990 All clauses
Appendix A, Appendix B, Appendix C and Appendix D of this standard are all appendices of the standard. This standard will replace GB/T4688-:1984 from the date of implementation. This standard is proposed by China Light Industry Federation
This standard is maintained by the National Technical Committee for Standardization of Paper Industry. The drafting unit of this standard is China Pulp and Paper Research Institute. The main drafters of this standard are Xue Chongyun, Lin Ru and Gong Ling. This standard is entrusted to the National Technical Committee for Standardization of Paper Industry for interpretation. GB/T4688—2002
ISO Foreword
ISO (International Organization for Standardization) is a global federation of international standardization bodies (ISO members). The development of international standards is carried out by ISO technical committees. Member countries interested in standards published by technical committees have the right to express their opinions to the committees. International organizations, governmental or non-governmental, related to ISO may also participate in this work. ISO has close links with the International Electrotechnical Commission (IEC) in the field of electrotechnical standards. The draft of an international standard must be voted on by the members of the technical committee before it can be formally adopted. The official publication of an international standard requires a vote rate of at least 75%. ISO 9184 was prepared by ISO/TC 6 Technical Committee Paper, Board and Pulp. ISO 9184 consists of the following parts, under the general title Paper, Board and Pulp - Analysis of Fibre Composition: Part 1: General Methods Part 2: Guide to Staining Part 3: Hersherg Staining Test - Part 4: Graff's Staining Test - Part 5: Lofion-Merritt Staining Test (Modified Wisbar Method) Part 6: Determination of Weight Factor by Fibre Coarseness Method Part 7: Determination of Weight Factor by Comparison Method Part 1 is a general guide to the fibre composition analysis process and should be used in conjunction with the Staining Guide (see Part 2) and Staining Tests (see Parts 3-5). Additional parts to this standard will be published as new fibre types or new staining tests are developed. Annexes A and B are an integral part of ISO 9184. 1 Scope
National Standard of the People's Republic of China
Analysis of fiber composition of paper, paperboard and pulp This standard specifies the analysis method of fiber composition of paper, paperboard and pulp. This standard is applicable to various pulps and most papers and paperboards. 2 Definitions
This standard adopts the following definitions.
2.1 Fiber coarseness fiber coarseness cncss
The mass of a specific fiber per unit length (absolute minimum), in grams per meter. 2.2 Weight factor weighrfacror
The ratio of the fiber coarseness of a specific fiber to the coarseness of a standard (specified) fiber. 3 Principle
GB/T 4688—2002
#qISO 9184:1990
Replaces GB/T 4688-1584
Fiber composition analysis is to take a small amount of representative fibers from the sample to be tested, dye them, and then observe them under a microscope. Qualitative analysis: Analyze according to the dyeing reaction of the fiber and the morphological characteristics of the fiber. Quantitative analysis: Measure the number of intersections between various red and case count lines, and use the weight factor to convert this number of intersections into mass fractions.
4 Reagents
In the analysis process, analytical reagents and distilled or deionized water should be used. 4.1 Sodium hydroxide (VaC)H) solution, mass fraction is about 1%, and 10g of sodium hydroxide is contained in each liter of solution. 4.2 Hydrochloric acid (HC1) solution, mass fraction of about 0.2%, each liter of solution contains 5 nL of hydrochloric acid. 4.3 Phosphoric acid (HPO4) solution, mass fraction of about 5%, each liter of solution contains 35 mL of 85% phosphoric acid. 4.4 Aluminum sulfate (SO4) solution, mass fraction of about 5%, each liter of solution contains 50 g of aluminum sulfate. 4.5 Potassium manganate (KMnO4) solution, mass fraction of about 6.5%, each liter of solution contains 65 g of potassium permanganate 4.6 Oxalic acid (C1O4-2H12O4) solution, mass fraction of about %, each solution contains 50 g of oxalic acid: 4.7 Organic solvents: ethanol (C1H2O4), ether (C1H2O4), ethyl acetate (CHCOOCH4), ketone (CHCOCH4), xylene [C1H2O4] (CH4) methyl ether (C1H2O4) ... ,II), chloroform (CHCI.), carbon tetrachloride (C,Cl) and triethane (C,H,Cl) 5.1 Microscope with mechanical stage, cross micrometer, center point or horizontal eyepiece. 40-120 times magnification is used for measuring and counting the number of fibers. 200~-500 times magnification is recommended for studying detailed structures: 5.2 Light source: light lamp or ordinary vacuum lamp with daylight filter. Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on October 15, 2002 and implemented on April 1, 2003. GB/T 46882002 5.3 Disperser: one is a low-speed disperser for easy-to-disperse samples, and the other is a mechanical or ultra-Luper disperser for difficult-to-disperse samples 5.4 Infrared lamp or hot plate: can maintain the temperature between 50℃ and 0℃. 5.5 Filtering device
5.5.1 Glass filter: 200ml, with 15μm~40μm sand core plate. 5.5.2 Sieve: 50mm-70mm in diameter, with metal or plastic edges, about 10mm in height, with a 200mm filter mesh at the bottom of the sieve. 5.6 Dropper: about 100m long, 5mm-8mm in inner diameter, glass tube with flat and unsealed ends and a capsule-like cover on the other end, with 0.5mL, 1.0mL scales engraved on the tube. 5.7 Microscope slide: size mm×75mm. 5.8 Microscope cover glass: size 22mm×22mm5.9 Dissecting needle and forceps: stainless steel.
5.10 Culture tube: diameter of about 100mm
5.11 Dropper bottle: 30ml. or 50mL. 6 Preparation of the sample
Tear off a sample of about 0.5 mm in width from different parts of the sample. For samples with multiple layers of knots, cut 5 mm×5 mm samples.
General sample
6.1.1 Boiling with water
Put the sample in a test tube or a small beaker and boil it for a few minutes while stirring constantly. Disperse it in a disperser and prepare filter discs for later use. 6.1.2 Boil in NaOH solution
If the sample cannot be completely dispersed according to the above method, move the sample to a test tube or beaker, boil it in NaOII while stirring constantly, filter it with a glass filter, wash it with water, neutralize it with HCl, and then disperse it in a disperser after washing with water for several minutes. Note: Samples containing wool or natural silk cannot be treated with Ne (H) because wool and natural silk are soluble in alkali, and boiling in NaOII also affects the color.
6.2 Specially treated samples
If the above method cannot disperse the sample, one of the following methods should be used to treat the sample. 6-2.1 Avoid strong paper
Put the shredded sample into a beaker. Add Al(SO4) or H2PO4 solution. Boil for 5min~30min depending on the dispersion speed of the sample. Pour out the solution with water and disperse the sample. If the sample cannot be dispersed, use an organic solvent to extract and then disperse it. Note: It is more effective to use chlorinated salt to disperse this type of product. 6.2.2 Plant parchment and high-beaten paper Put the shredded sample into a beaker containing KMnO2 solution and let it stand for 1h, then pour out the solution, wash twice, treat with oxalic acid solution and then wash and disperse.
6.2.3 Samples that have been diffused or specially glued - The fiber has a high binding strength. The sample can be extracted with cold and hot organic solvents. The fiber can be dispersed continuously. The selected solvent should not affect the fiber. 6.2.4 Colored samples
If the fibers are still colored after dispersion, it will be difficult to identify the fibers. Therefore, a method related to the slurry is often used to remove the color. For example, use a reagent to extract the sample, oxidize and reduce it, etc. 6.2.5 Multi-layer samples
When the sample is two or more layers of paper or paperboard, the layers should be analyzed separately. Cut 5 pieces of test pieces of about 50 μm>50 μm from the sample and soak them in hot water at about 70°C until the layers are completely separated. If delamination is difficult, use NaOH solution instead of water. If the separated layer contains fibers from adjacent layers, remove them carefully after soaking. Each layer should be treated in reverse order as a normal sample. 7 Staining and preparation of fiber slides
GB/T 4688—2002
The method of staining and preparation of slides depends on the dye used. Select the appropriate dye from Appendix A. Select the corresponding staining method from Appendix R, Appendix D. Staining of fibers in slides or tubes 7.1 Slides [Staining]
Fiber slides for staining can be prepared from a diluted fiber suspension or from fibers in a filter. 7.1.1 Preparation of slices using fiber suspension
Dilute about half of the dispersed fiber suspension in a beaker to a concentration of about 0.05% by mass. Use a tube to drop 1.0 ml of the suspension onto a clean, grease-free microscope slide. Use a dissecting needle or tap the slide to evenly disperse the fibers. Dry the slide under a hot plate or infrared lamp, then select the appropriate dye to stain. After staining for 1 min to 2 min, cover with a cover slip to avoid bubbles. Use filter paper to absorb excess dye. The sample can be observed and analyzed. 7.1.2 Preparation of fiber slides with filter discs
Filter the dispersed red suspension with a sieve or glass filter. Place the filtered fiber filter disc in a small medium to prevent drying. Take a small amount of fiber and transfer it to a slide. Add two drops of the selected stain. Use a dissecting needle to evenly disperse the fiber. After covering the cover glass, try to avoid fiber flocculation. It is best to tilt the fiber slide and use absorbent paper to remove excess stain from the edge. 7.2 Coloring in a test tube
Take a sample from the filtered fiber filter disc and stain it in a test tube according to the appropriate method. Then replace the stain with water and prepare the slide as described above.
8 Experimental procedures
Because some stains are unstable, they should be analyzed immediately after preparation. 8.1 Qualitative analysis
Place the dyed fiber slide on the stage of the microscope, and move the slide slowly and regularly in a horizontal or vertical direction in a line to observe the entire fiber area. According to the fiber shape characteristics and dyeing conditions, identify the fiber type and pulping method. Observe at least two slides. For fibers that are difficult to identify, observe one or more slides. 8.2 Quantitative analysis
Move the fiber slide with the help of the stage so that the central light spot of the helioscope falls on the 3mm1-5cm square corner of the cover glass. n1. Then slowly move the slide one by one in the horizontal or vertical direction, line by line, so that the entire fiber range is observed and the types of fibers are counted as follows.
Use a multi-digit counter and count and record the number of each fiber or broken fiber as it passes through the center of the field of view. If a fiber passes this center point multiple times, count it once for each pass; if a fiber moves along the center of the field of view, count it only once. Very small fiber fragments can be ignored, and those with larger longitudinal fissures should be counted. When the same type of fiber fragments are observed on the same observation line, three are counted as one. If the content of thrombin and other small cells is very small and can be ignored, one fiber in the fiber sequence is counted as one. If the fiber continues to pass through the field of view, it will be counted as one. If it is difficult to count the number of fibers of each type at one time, the process can be repeated until all the fibers are counted. In the process of continuous counting, the slide should not be moved from the original row to the original row. When the fibers of an observation line are counted, the slide should be moved about 5 meters to another observation line, and the fibers of this row should be counted according to the above method. More than two slides should be counted so that the number of intersection points of the counted fibers is more than 600. If the colors of different types of fibers are not very different, they can be counted with the help of the morphological characteristics of the fibers. If there are a large number of thin-walled cells, they should be recorded as a part. When four thin-walled cells of the same type appear in the same row, they should be accumulated into one number.
9 Representation of results
9.1 Qualitative analysis
GB/T 4688—2002
Based on the results of microscopic analysis, the type of fiber and the pulping method can be analyzed. Those fibers that are difficult to distinguish from other fibers and those that exist in small quantities but are very similar in shape can be considered as a group. 9.2 Quantitative analysis
9.2.1 Weight fraction
The weight fraction W of each fiber component can be obtained by formula (1), w, =
where .—weight factor;
W—weight fraction, %;
n—the total number of crosses of the same fiber;
Fresh fiber group effect
The weight fraction of each fiber to the whole fiber should be reported. If the weight fraction is less than 2, it should be reported as "trace". 9.2.2 Weight factor\
The weight factor f can be calculated according to formula (2). X 100
f: - C/0. 180
Wherein:
Weight factor;
Fiber coarseness, mg/m+
Fiber coarseness of cotton linter fiber, ng/ml. 10 Test report
The test report should include the following contents:
a) This standard number:
6) All necessary instructions for completing sample identification:
C) For multi-layer products such as red board, separate layer analysis should be carried out d) The dyeing method used;
Ratio) Qualitative analysis includes:
Fiber type;
Polymerization method;
Whether bleached or not.
f) Qualitative analysis results:
The number of roots of each fiber;
Weight factor;
Whether thin-walled cells are included.
B) Any situation that may affect the test results. ...1)
GB/T 4688—2002
Appendix A
(Standard Appendix)
Dyeing Guide
The dye should be selected according to the requirements of the sample analysis. The available dyes are listed in Table A1. Table A1 Dyeing Guide for Fiber Proportion Analysis
Special Samples
Chemical Pulp, Rag Pulp
Machine Pulp
Semi-Chemical Pulp
Last-Source Conifer Chemical Pulp
Bleached Conifer Chemical Pulp
Unsourced Conifer Kraft Pulp
White Conifer Vegetable Pulp
Unwoven Conifer Kraft Pulp||tt ||Bleached sulphite pulp
White sulphite pulp
White sulfite pulp
Coniferous wood chemical pulp
Cyclic wood chemical pulp
Unbleached semi-chemical sulphur pulp
Unbleached semi-chemical sulfite pulp
Coniferous wood mechanical pulp
Broadleaved wood mechanical pulp
For details on the preparation and application of dyeing, please refer to Appendix B, Appendix C and Appendix D. Dyeing agent
Herzbetg
Herzberg,Graff\C\
Lalton-Merritt
Lofton-Merritt| |tt||Graif\c\
Graifc
Graff\c”
Lofton-Merritt
Grafi\c
GB/T 4688 - 2002
Appendix B
(Appendix to the standard)
Herzherg dyeing test
Herzherg dye is used to qualitatively and qualitatively distinguish chemical pulp, machine-cut pulp and rag pulp. This dye can also be used to qualitatively identify semi-chemical pulp and distinguish viscose fibers from subsequent fibers. B1 Reagent
Analytical reagents and distilled or deionized water should be used. B1.1 Saturated zinc chloride solution in room temperature
Add zinc oxide (t:t,) to about 10 mL of initial water until the remaining solute does not dissolve. Allow it to cool to room temperature and observe the crystallization of zinc chloride. Store this solution in a brown reagent bottle for later use. B1.2 Pour the solution
Mix 2.g of potassium iodide (KI) and 1R of iodine (L). Use a pipette to add 5mL of water drop by drop. Stir while adding water to mix. It is very important to dissolve iodine in a small amount of water. Potassium iodide is used to dissolve iodine. If there is any iodine residue that has not been dissolved, it may be because the water was added too quickly. This solution should be discarded. B1.3 IIcrzherg stain
Mix 15 mL of zinc fluoride solution with B12 iodine solution and let stand for 6 hours to allow any sediment to settle. Gently pour the clear solution into an empty brown dropper bottle and add a small piece of iodine to the dropper bottle. Store the solution in a dark place when using it. Prepare a fresh stain every two months
Before using the new stain, check with known fibers. Cotton fibers should be wine red. If it is light blue, it means that the zinc chloride bath is too concentrated and should be diluted with a small amount of water. Chemical fibers should be blue-light purple. If it is light red, it means that the zinc chloride concentration is too low and a small amount of saturated zinc flakes should be added for dilution.
B2 Test steps
B2.1 Staining
Add 2 drops to 3 tablespoons of Ht:rzhr:rg stain on a fiber slide to stain the fiber. B2.2 Place the stained fiber slide under a microscope and observe at a magnification of 4 to 120 times. Identify the fiber type and calculate the fiber ratio based on the color of the Herzberg stain (see Table B1) and the fiber morphology. Table 1 Herzherg dye color reaction table Type
Chemical pulp (Mu pulp, Tao wheat straw pulp, Spanish straw pulp) Mechanical pulp (non-pulp, Bang wheat straw pulp, Huang Ai, etc.) Pibu pulp (cotton, sub-bottom, Dasen, storage hemp, etc.) Semi-chemical pulp and chemical mechanical pulp
Regenerated fiber fiber (viscose fiber, etc.)
Cellulose acetate fiber
Taicheng Shuwei
Blue light blue-purple blue
Wine red
Lamp color, wax yellow, mixed vegetable color and yellow dark light kettle color-violet blue
Colorless to light brown yellow
GB/T 4688—2002
The raw pulp of coniferous kraft pulp is yellow: chemical pulp fiber is blue, the depth of blue depends on the pulping process and the degree of delignification, and the fiber with incomplete delignification is yellow
The color obtained by Herzherg dye is unstable, the blue of chemical pulp fiber will gradually become darker, and the yellow of mechanical pulp fiber will gradually become gray.
Note: In addition to the above main color differences, there are other phenomena that can be used to help analyze the fiber composition. Herzherg staining can be used to judge whether there is sulfonate sulfonate pulp based on the yellow color of the resin in the ray cells of sulfonate sulfonate pulp. GB/T4688—2002
Appendix C
(Appendix to the standard)
Grafe C dyeing test
Grafe C dyeing agent has a wide range of applications and can identify almost all commonly used papermaking fibers. In actual use, Graff C dyeing agent is mainly used in the following aspects: · Distinguishing chemical pulp, semi-chemical pulp and mechanical pulp. · Distinguishing coniferous bleached sulfite pulp and sulfite pulp. Generally speaking, the color difference can meet the requirements of fiber counting. Need to distinguish between hardwood kraft pulp and sulfite pulp. The color difference of unbleached pulp is more obvious than that of bleached pulp. Distinguish between softwood pulp and hardwood pulp (except dissolving pulp). The color difference of kraft pulp is obvious, while sulfite pulp can be distinguished in most cases, but the color difference is slightly smaller. Distinguish between bleached rice straw pulp and Spanish straw pulp in softwood pulp. The color difference is obvious. C1 reagent
Use analytical reagent and distilled water or deionized water. C1.1 Aluminum fluoride solution (20℃C, p=1. 16 g/mL): Dissolve about 40 g of aluminum fluoride hexahydrate (A1Cl:·6H2O) in 10 ml of water. C12 Calcium fluoride solution (20°C, pH = 1.3 g/mL): Dissolve about 100 g of calcium chloride (CaCl) in 150 ml of water. C1.3 Zinc chloride solution (20°C, pH = 1.82 g/mL): Add about 100 g of zinc chloride (ZnCl2) to about 50 ml of warm water until the residue no longer dissolves, cool it to room temperature, and observe that a small amount of zinc chloride should precipitate. C1.4 Iodine solution: Mix 0.90 g of potassium iodide (KI) and 0.65 g of iodine (I). Add dropwise to 50 ml of warm water with a dropper. mL of water into the mixture and stir continuously. If some iodine is not dissolved, it may be that the water is dissolved too quickly and the paint should be discarded. Store the above solution in a brown reagent bottle. The iodine solution should be prepared again every 2 or 3 months. CP
Graff\C\ Preparation of stain
Mix four solutions according to the following requirements: 20 T1L of lead chloride solution (t:1.1), 10 ml of calcium fluoride solution (C1.2), 10 mL of zinc oxide solution (C1.3) and 12.5 mL of iodine solution (C1.4). Use a pipette to take the required solution of C1.1, C1.2 and Cl.3. Place in a measuring tube and mix evenly. Add the required stock solution (C1.4). Mix further and let stand in the dark. After 12h~24h, when all the sediment has settled, pour the supernatant into a brown dropper bottle and add a small piece. The dye should be stored in a dark place when not in use. Fresh dye should be prepared about every 2-3 months. Before using the fresh dye, it should be checked with a sample containing bleached coniferous kraft pulp and sulfite pulp. If the dyed color does not match the color given in Table C1, it can be checked again with a little iodine solution (I,). If the color is still not satisfactory, it should be remixed.
3 Test steps
C3.1 Dyeing
Add 2 or 3 drops of GraIF\C\ dye to the fiber slide [: to dye the fiber, C3. 2. The test is to place the dyed fiber slide under a microscope and observe it at 40-120 times magnification. According to the color reaction obtained by Graff "\ dye, the fibers are identified and measured, as shown in Table C1. Coniferous wood chemical pulp
Broadleaf clothing chemical pulp
Semi-chemical pulp
Mechanical pulp
Classic and Spanish chemical pulp
Blanket pulpbZxz.net
Notes on Table C1:
GB/T 4688--- 2002
Table C1Graff\C\Color Reaction Table of Dyes
Unexcited Vegetable Pulp
White Vegetable Pulp
Dissolving Grade Sulfate Pulp
Unsulfite Pulp
Bleached Sulfite Pulp
Dissolving Grade Sulfite Pulp
Unsulfite Pulp
Bleached Sulfite Pulp
Dissolving Grade Sulfite Pulp
Deep Source Sulfite Pulp
Bleached Sulfite Pulp
Dissolving Grade Sulfite Pulp
Softwood Pulp
Unbleached Natural Pulp
White Broadwood Pulp
Unbleached Pulp
Dart White Pulp| |tt||, flax, hemp, some hemp
light yellow and brown
light blue-grey or gray
light brown-purple
different shades of yellow
light brown
light brown or purple
light blue-green or blue
little blue
blue-purple
light gray with bone yellow
mixed blue or charcoal
light brown
violet yellow
different shades of light green
bright brown (similar to bleached kraft pulp) bright yellow
light green blue (most fibers are this color) eastern blue, blue-purple.Bright blue (similar to bleached hardwood pulp) Burgundy or brownish red
(1) The colors obtained by Graff\C\ dyes have a variety of shades, and different analysts express different opinions. Therefore, it is not necessary to describe the colors similarly in the report document. Some fiber compositions cannot be analyzed based solely on the color changes of the dye, and some knowledge of fiber morphology is also required.
(2) Graff\C\ dyes turn the resin-containing wood ray cells yellow, and coniferous sulfite pulp also often has this color:
(3) Different types of dissolving pulps are often indistinguishable. (1) If the sample is boiled in an ammonia solution before pretreatment or before dyeing, the differences between hardwood mechanical pulp and coniferous mechanical pulp are as follows:
Coniferous mechanical pulp: bright yellow:
Coniferous mechanical pulp: light green.
GB/T 4688--2002
Appendix D
(Appendix of the standard)
Lofton-Merritt dyeing test
Lofton-Merritt dyeing test can be used for the specific analysis of the following pulps. Unbleached and bleached softwood pulp:
Unbleached sulphate pulp and unbleached industrial sulphate pulp in softwood pulp; unbleached sulphate semi-chemical pulp and unbleached sulphite pulp. D1 reagent
Note: Some chemicals used in this dye are toxic. Therefore, the preparation of the dye and the dyeing process should be carried out in an environmental laboratory.
Analytical reagents and distilled or deionized water should be used. D1.1 Fuchsin solution with a mass fraction of 1%
Boil 50mL of water in a 250mL beaker, add 1g of monomeric hydrogen chloride fuchsin (CHN,CI) little by little, and stir vigorously, then dilute to 100mL.
D1.2 Malachite green solution with a plasmolysis fraction of 2% and 2g of malachite green (aHaN,Cl). The preparation process is as described for the fuchsin solution: D1.3 Hydrochloric acid solution with a mass fraction of 0.5% Dilute 37% hydrochloric acid (HCl) 5ml. solution to 400mL and store the above solutions in brown reagent bottles. D141. Preparation of Ophior-Merri dye Mix according to the following requirements: Fuchsin solution (D1.1) 4.4tmL: Malachite green solution (D1.2) 2.2ml.; Hydrochloric acid solution (I) t.3) 20.0ml.
Use a pipette to take the required volume of the above solution into a 10ml volumetric flask and dilute to 100ml. When not in use, store this solution in a brown reagent bottle and store it in a dark place. Shake it before use; adjust the dye mixture by adding malachite green and fuchsin solutions to obtain the color response shown in Table [1. Table D] Laften-Merritt Dyeing agent color pulp
Unbleached sulphate pulp
Leaf wood chemical pulp
Leaf wood chemical pulp
Softwood and hardwood semi-chemical pulp
Unbleached sulphite pulp
Bleached sulphate and sulphite pulp
Semi-bleached sulphate pulp
Bleached sulphate and sulphite pulp
Semi-bleached or bleached sulphate and sulphite pulpUnbleached pulp
Bleached sulphite pulp
Mechanical pulp||t t||Light green or grayish blue
Red
Light pink
Light green solid color
Almost no color
Light salt green
Light blue purple
Use known samples containing coniferous unbleached sulfate pulp, sulfite pulp and mechanical pulp to test the newly prepared dye. If the unbleached sulfate pulp fiber or mechanical pulp fiber appears light red, add some malachite green liquid; if the unbleached sulfite pulp fiber appears light blue
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