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Vieira et al. (2022). “Toilet paper perforation efficiency,” BioResources 17(1), 492-503. 492
Toilet Paper Perforation Efficiency
Joana C. Vieira,a,* André C. Vieira,b António de O. Mendes,a Ana M. Carta,c
Paulo T. Fiadeiro,a and Ana P. Costa a
Today, the toilet paper market offers product types with varying number of
plies, providing better mechanical strength and liquid absorption. Several
tissue paper perforation systems exist, and the best commonly applied is
a top-cutting mechanism that includes an oblique blade, a combined
oblique blade, or a simple spiral blade. The perforation efficiency must be
high to have an easy sheet separation from the roll of the toilet paper,
which does not always occur. Hence, consumer satisfaction can depend
on the perforation performance. To study this, a laboratory perforation
system was used to perforate different commercial toilet papers (in brands
and number of plies) and evaluate their perforation efficiency. A finite
element method (FEM) was used to simulate the curve of the progression
of perforation efficiency as a function of the cut distance. The main findings
were a stabilization of the perforation efficiency from a cut distance of 6
mm and a 15% increase in the cut distance for the laboratory blade to
match the industrial perforation efficiency. The FEM analysis confirmed
the behavior of the evolution of perforation efficiency with the increase of
the cut distance.
DOI: 10.15376/biores.17.1.492-503
Keywords: Tissue toilet paper; Perforation efficiency; Finite element method (FEM); Mechanical behavior
Contact information: a: Fiber Materials and Environmental Technologies (FibEnTech-UBI), Universidade
da Beira Interior, R. Marquês D’Ávila e Bolama, 6201-001 Covilhã, Portugal; b: Center for Mechanical
and Aerospace Science and Technologies (C-MAST-UBI), Universidade da Beira Interior, R. Marquês
D’Ávila e Bolama, 6201-001 Covilhã, Portugal; c: RAIZ - Instituto de Investigação da Floresta e Papel,
Aveiro, 3801-501, Portugal; *Corresponding author: joana.costa.vieira@ubi.pt
INTRODUCTION
The use of toilet paper was first recorded in China in 851 AD (Bennett 2009). The
perforated roll toilet paper known today originated in the 19th century, with the patent of
Seth Wheeler in 1894 (Wheeler 1894). The toilet paper market presents this product with
a diverse number of plies (1 to 6 plies). A greater number of plies increases the thickness,
which provides greater strength and liquid absorption. Globally, tissue paper, with toilet
paper is included, is the fastest growing sector of the paper industry, where each person in
the world consumes an average of 4.4 kg per year (Haggith and Martin 2018). From the
specifications of a 3-ply toilet paper roll with 150 sheets, it weighs about 78 g. This means
that each person in the world consumes about 56.5 rolls per year (more than 1 roll per week
per person). Between 2010 and 2015, tissue paper production increased 3.5% annually, and
it is expected to grow almost 6% per year between 2018 and 2022. The environmental
benefit that has been seen, despite this rapid evolution of the tissue market, especially in
developing countries, is to compensate the increase of digitization and the decline in the
use of printing and writing paper (Skene and Vinyard 2019).
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Vieira et al. (2022). “Toilet paper perforation efficiency,” BioResources 17(1), 492-503. 493
Today, the use of disposable products is high, but many consumers are concerned
with the level of resources needed to produce these products. Thus, the development of
environmentally friendly disposable products remains an important work (Olson et al.
2016). Tissue paper products, such as kitchen, toilet, and facial papers, are similar and
usually perforated to facilitate portioning (Ogg and Habel 1992; Schulz and Gracyalny
1998; Baggot et al. 2006). In a roll of perforated toilet paper, the holes with a certain cut
distance along a line are called perforation lines. These lines of weakness are parallel to
the axis on which the toilet paper is rolled and aim to divide the roll of toilet paper into
portions with a predefined length. This predefined length between two perforation lines is
known as a “sheet” (Ogg and Habel 1992; Chih 2018). Figure 1 shows a scheme that
presents these concepts.
Fig. 1. Diagram of the concepts associated with toilet paper perforation
In the existing tissue paper perforation techniques, an upper cutting blade and a
lower roll are generally used. Currently, the most widely used top-cutting mechanism
includes an oblique blade, a combined oblique blade, or a simple spiral blade (Shiang
2012). Because the perforation blade operates in a rotating spiral, the contact between the
blade and the paper sheet is theoretically at one point, which reduces the impact of this on
the sheet. The soft contact (low impact) between the perforation blade and the paper sheet
increases its lifetime and decreases the failure phenomena, such as the break of the blade
(Chih 2018). There are disadvantages in the methods currently known for perforating tissue
paper sheets. The forces generated in this operation cause vibrations that are harmful to the
general processing of the sheet. In addition, there must be well-defined speed limitations,
because high processing speeds cause high levels of vibration, causing imperfections in
sheet cuts, sheet breaks, and/or machine malfunction (Baggot et al. 2006).
When the tensile strength of the perforated toilet paper is strong, the paper sheet is
split off the perforation line. In contrast, when the tensile strength is weak, the sheet when
pulled out from the toilet paper roll is not well controlled, leaving more than a
predetermined number of sheets (Schulz and Gracyalny 1998; Mukai and Shimizu 2003).
This low tensile strength can also impair the runnability of the converting machine, causing
successive breaks of the sheet after the perforation process. Therefore, for all of this to be
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Vieira et al. (2022). “Toilet paper perforation efficiency,” BioResources 17(1), 492-503. 494
avoided, the tensile strength in the machine direction (MD) of the perforation must be
controlled so that it falls within a predetermined range. In contrast, the tensile strength of
perforated toilet paper is greatly influenced by the tensile strength of the base paper itself
in MD (fibrous composition, formation, and orientation of the paper sheet) (Mukai and
Shimizu 2003). These problems, which are associated with the separation of the sheets by
the consumer, can have a negative impact on the customer's loyalty and satisfaction with
the brand of the product in question (Schulz and Gracyalny 1998). Thus, the study of the
perforation efficiency, by definition “the difference between the tensile strengths of non-
perforated and perforated material from the same sample divided by the tensile strength of
non-perforated material,” of a toilet paper is extremely important for the producers of this
type of product (ISO 12625-1:2019). To have an easy sheet detachment from the toilet
paper roll, the perforation efficiency must be high. Equation 1 is used to evaluate the
perforation efficiency according to the standard ISO 12625-12 (2010),
Ep = 100 × [1 - (Sp/ Snp)] (1)
where Ep is the perforation efficiency (%); Sp is the average tensile strength of perforated
papers (N/m); and Snp is the average tensile strength of unperforated papers (N/m).
In this context, the objective of the present work is to evaluate the perforation
efficiency for different cut distances in commercial papers of 2, 3, 4, and 5 plies, using a
laboratory perforation system and comparing them with the industrial perforation of each
one of these.
EXPERIMENTAL
Materials
Eight commercial toilet papers with a minimum service length of 125 mm were
selected. This set is composed by two samples of each 2-ply, 3-ply, 4-ply, and 5-ply papers.
These toilet papers were identified according to the following legend: XPi, where X is the
commercial toilet paper sample brand, Pi is the number of plies, and XPiCj where Cj is the
cut distance (mm) of the perforation. The values of i = 2, 3, 4, and 5 represents the number
of plies, and j = 2, 3, 4, 5, 6, 7, and 8 mm represents the cut distances performed.
Methods
To start this work, samples of commercial toilet paper with sheet length of 125 mm
minimum were selected, meeting the ISO 12625-12 (2010) standard requirement of the
100 mm gauge length. Then, the samples were prepared to perform the tensile tests
according to the above referred standard (width of 50 mm and a length of a minimum of
125 mm up to 150 mm). These samples were then perforated in the laboratory with the
repeated cutting distances of 2, 3, 4, 5, 6, 7, and 8 mm. All the perforations were performed
in the center of each sample along the cross direction (CD).
All samples were subjected to tensile tests along the MD on a Thwing-Albert®
VantageNX universal testing machine (Thwing-Albert Instrument Company, West Berlin,
NJ, USA) at a rate of elongation of 50 mm/min, in accordance with the standard mentioned
above. Samples tensile tests were performed with and without perforation as illustrated in
Fig. 2. A customized optical system (Mendes et al. 2013, 2014, and 2015) was used to
record the measurements of the cut distance of the toilet paper samples. The image
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Vieira et al. (2022). “Toilet paper perforation efficiency,” BioResources 17(1), 492-503. 495
acquisition of the performed cut distances was carried out with precise requirements of
lighting and magnification. After it was properly configured for the application in hand,
the optical system allowed the observation of the elements to be measured using processing
tools for this task. In this work, four different measurements were considered of each
sample, which were used for the calculation of the corresponding mean and standard
deviation for all the studied paper samples.
Fig. 2. Set-up of the tensile tests without and with perforation (Vieira et al. 2021)
All toilet paper samples were stored and tested at a temperature of 23 ± 1 °C and a
relative humidity of 50 ± 2% according to ISO 187 (1990).
Numerical Model
In this work for the 2-ply toilet paper (BP2) the influence of the cut distance was
studied using mechanical simulation tools. The aim was to evaluate how the tensile strength
decreases with the cut distance and how it affects the perforation efficiency. A simpler
model was used to verify the stabilization of the perforation efficiency from a cut distance
of 6 mm.
A finite element model (FEM) was executed in the software Abaqus/Standard finite
element (Dassault Systèmes®, version 14.1, Vélizy-Villacoublay, France), using a linear
elastic constitutive model to replicate the tensile tests on the 2-ply toilet paper BP2 with 2,
3, 4, 5, 6, 7, and 8 mm of cut distances. The Young’s modulus used, 1.38 MPa, was
obtained by the tensile test performed in the sample without perforation and calculated as
the slope between two specific points in the initial linear part of the load-elongation curve.
An estimated value of 0.3 was used for the Poisson coefficient assuming that volume does
not change. The sample geometry was a single shell with a width of 50.0 mm, a length of
100.0 mm, and a thickness of 0.3 mm. An axial load was employed by controlling a uniform
elongation of 10.0 mm of the top surface. The lower surface was constrained to move and
rotate in all directions. The CPS4R elements used in these models were 23503, 16043,
15252, 13222, 13165, 12158, and 12139 for the cut distances of 2, 3, 4, 5, 6, 7, and 8 mm,
respectively. An ellipse was used for the cut’s geometry with 0.01 mm to the smaller
diameter and the longer diameter was matched to each cut distance. Perforation efficiency
was calculated based on the tensile strength of the toilet paper sample without perforation.
Load was increased iteratively, in several simulations, until this tensile strength value (Snp
= 265.89 MPa in accordance with Table 1 for BP2) was reached in the most critical element.
The procedure was the same for each cut distance.
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Vieira et al. (2022). “Toilet paper perforation efficiency,” BioResources 17(1), 492-503. 496
RESULTS AND DISCUSSION
From the previous work by Vieira et al. (2021), these toilet papers (with the same
notation) were morphologically characterized. The fiber composition of the samples is
mostly composed by hardwood short fibers. However, small differences were found in
softwood long fibers content.
Tables 1 and 2 show the results for determining the perforation efficiency, as well
as the measurements of the cut and blank distances laboratory performed for the 2-, 3-, 4-,
and 5-ply toilet papers.
In Fig. 3, the cut distance measurements made on all toilet paper samples by cut
blade size are shown. All the effective cuts were inferior to the target cuts. Comparing all
the cuts for the same cut blade, they had an average coefficient of variation of 2.1% which
indicates that this is a good mechanical method of laboratory perforation for this kind of
tissue paper sample.
Fig. 3. Evaluation of the cut distances for all study samples
The evolution of perforation efficiency with the variation of the cut distances is
presented in Fig. 4, by number of plies of toilet paper. It can be confirmed that for all
samples there was a stabilization of the perforation efficiency above a cut distance of 6
mm. Therefore, for cutting distances higher than this value, perforation efficiency is not
gained, which may impair the runnability of the paper sheet in the converting machine. In
the previous work Vieira et al. (2021), the authors concluded that with the increase of the
cut distance, stress concentration factor tends to increase asymptotically, physically
meaning that the stress gets more homogenously distributed. Because the samples are from
commercial papers of different brands, they have different fibrous compositions, which
justifies the gap between the curves for the toilet papers with the same number of plies.
Images obtained by the customized optical system are shown in Fig. 5, which represents
the 6 mm cut distance of the 2-, 3-, 4-, and 5-ply toilet papers. The figure verifies that
samples had uniform and clean cuts, and that with the increase of the number of plies the
cut was not affected.
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Table 1. Perforation Efficiency and Cut Distance for 2-ply and 3-ply Toilet Papers
Toilet
Paper
ID
Tensile
Index
(Nm/g)
Tensile
Strength
(N/m)
Perforation
Efficiency
(%)
Target
Cut
Distance
(mm)
Cut Distance
Measured
(mm)
Blank
Distance
Measured
(mm)
±
±
±
QP2
5.87
0.19
175.38
QP2C2
3.49
0.24
104.34
40.5
2
1.92
0.05
1.15
0.03
QP2C3
2.58
0.20
77.26
55.9
3
2.73
0.08
1.21
0.06
QP2C4
2.13
0.16
63.65
63.7
4
3.60
0.02
1.27
0.04
QP2C5
1.73
0.19
51.80
70.5
5
4.59
0.05
1.22
0.03
QP2C6
1.37
0.10
41.09
76.6
6
5.58
0.04
1.18
0.05
QP2C7
1.34
0.15
40.08
77.1
7
6.77
0.05
1.19
0.03
QP2C8
1.00
0.10
39.85
77.3
8
7.75
0.27
1.21
0.03
BP2
7.13
0.44
265.89
BP2C2
3.65
0.28
136.05
48.8
2
1.87
0.04
1.11
0.02
BP2C3
2.83
0.26
105.72
60.2
3
2.82
0.07
1.20
0.05
BP2C4
2.14
0.31
79.67
70.0
4
3.75
0.09
1.19
0.06
BP2C5
1.78
0.19
66.33
75.1
5
4.75
0.10
1.17
0.07
BP2C6
1.23
0.13
46.82
82.4
6
5.75
0.10
1.12
0.05
BP2C7
1.22
0.12
45.51
82.9
7
6.60
0.08
1.20
0.03
BP2C8
1.12
0.13
41.82
84.3
8
7.88
0.17
1.14
0.07
HP3
7.00
0.22
305.25
HP3C2
3.35
0.35
146.01
52.2
2
1.76
0.06
1.15
0.09
HP3C3
2.78
0.14
121.19
60.3
3
2.69
0.07
1.22
0.06
HP3C4
2.12
0.09
92.53
69.7
4
3.55
0.06
1.22
0.04
HP3C5
1.85
0.23
80.65
73.6
5
4.63
0.07
1.21
0.07
HP3C6
1.32
0.10
57.39
81.2
6
5.65
0.16
1.09
0.07
HP3C7
1.20
0.14
52.54
82.8
7
6.57
0.05
1.22
0.01
HP3C8
1.13
0.15
50.06
83.6
8
7.79
0.18
1.19
0.07
JP3
6.86
0.21
360.10
JP3C2
3.38
0.16
177.61
50.7
2
1.74
0.07
1.18
0.07
JP3C3
2.69
0.26
141.22
60.8
3
2.91
0.05
1.21
0.04
JP3C4
2.15
0.21
113.04
68.6
4
3.75
0.06
1.19
0.05
JP3C5
1.69
0.13
88.53
75.4
5
4.82
0.11
1.15
0.06
JP3C6
1.19
0.13
62.46
82.7
6
5.83
0.17
1.11
0.06
JP3C7
1.21
0.16
63.63
82.3
7
6.86
0.10
1.13
0.06
JP3C8
1.29
0.18
63.60
82.3
8
7.81
0.17
1.15
0.06
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Table 2. Perforation Efficiency and Cut Distance for 4-ply and 5-ply Toilet Papers
Toilet
Paper
ID
Tensile
Index
(Nm/g)
Tensile
Strength
(N/m)
Perforation
Efficiency
(%)
Target
Cut
Distance
(mm)
Cut Distance
Measured
(mm)
Blank
Distance
Measured
(mm)
±
±
±
KP4
6.78
0.29
410.05
KP4C2
3.71
0.22
224.70
45.2
2
1.85
0.03
1.17
0.04
KP4C3
2.88
0.19
174.33
57.5
3
2.80
0.03
1.10
0.06
KP4C4
2.29
0.10
138.44
66.2
4
3.64
0.08
1.25
0.07
KP4C5
1.85
0.21
111.97
72.7
5
4.66
0.17
1.16
0.05
KP4C6
1.48
0.18
89.47
78.2
6
5.75
0.15
1.12
0.04
KP4C7
1.29
0.08
78.30
80.9
7
6.62
0.08
1.14
0.04
KP4C8
1.20
0.18
74.81
81.8
8
7.63
0.16
1.17
0.04
MP4
8.89
0.40
611.07
MP4C2
4.44
0.33
305.24
50.0
2
1.78
0.10
1.18
0.07
MP4C3
3.55
0.10
243.75
60.1
3
2.79
0.06
1.13
0.04
MP4C4
2.97
0.09
204.28
66.6
4
3.71
0.03
1.18
0.02
MP4C5
2.26
0.24
155.20
74.6
5
4.93
0.09
1.11
0.06
MP4C6
1.71
0.15
117.25
80.8
6
5.80
0.12
1.10
0.08
MP4C7
1.64
0.12
112.73
81.6
7
6.70
0.09
1.16
0.06
MP4C8
1.52
0.21
108.33
82.3
8
7.91
0.14
1.11
0.08
OP5
7.53
0.27
572.06
OP5C2
3.60
0.31
273.28
52.2
2
1.85
0.05
1.13
0.08
OP5C3
2.63
0.20
200.22
65.0
3
2.75
0.08
1.10
0.05
OP5C4
1.92
0.19
146.03
74.5
4
3.72
0.14
1.21
0.03
OP5C5
1.73
0.16
131.60
77.0
5
4.63
0.06
1.13
0.03
OP5C6
1.32
0.11
100.28
82.5
6
5.70
0.07
1.05
0.01
OP5C7
1.21
0.10
91.79
84.0
7
6.60
0.08
1.24
0.07
OP5C8
1.08
0.16
87.97
84.6
8
7.86
0.18
1.15
0.05
RP5
5.54
0.35
423.59
RP5C2
3.39
0.24
258.71
38.9
2
1.78
0.11
1.12
0.06
RP5C3
2.60
0.22
198.85
53.1
3
2.71
0.04
1.18
0.04
RP5C4
2.06
0.21
157.46
62.8
4
3.71
0.09
1.20
0.03
RP5C5
1.53
0.16
116.95
72.4
5
4.84
0.08
1.14
0.07
RP5C6
1.31
0.10
100.43
76.3
6
5.92
0.07
1.14
0.06
RP5C7
1.30
0.06
99.09
76.6
7
6.84
0.12
1.13
0.09
RP5C8
1.12
0.12
95.90
77.4
8
7.57
0.13
1.13
0.07
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Fig. 4. Evolution of perforation efficiency with the variation of the cut distances: a) 2-ply toilet
paper; b) 3-ply toilet paper; c) 4-ply toilet paper, and d) 5-ply toilet paper
Fig. 5. Optical images of the 6 mm cut distance from: a) 2-ply toilet paper; b) 3-ply toilet paper; c)
4-ply toilet paper; and d) 5-ply toilet paper
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Figure 6 presents the confirmation of the perforation efficiency stabilization to a
cut distance of 6 mm by the FEM simulation. This curve shows the same behavior as the
curves related to experimental data. The gap between the curves of simulation and
experimental data is due to the parameters assumed for the simulation, i.e., despite the
Young's modulus and the sample dimensions being the same, it was considered to be one
homogeneous and isotropic shell (although 2-plies in toilet paper), not considering the
fibrous orientation, friction between plies, volume changes due to creping, and embossing.
Another justification is the fact that the FEM simulation is performed for an exact cut
distance (target dimension) and the cut distance performed in the laboratory is always
smaller than the target dimension (according to the values presented in Tables 1 and 2).
Fig. 6. Comparison of the evolution of perforation efficiency with the variation of the cut distances
of the FEM simulation, laboratory (LAB) perforation, and industrial (IND) perforation results for a
2-ply toilet paper (BP2)
Figure 6 shows the industrial perforation of the same commercial toilet paper.
Comparing laboratory perforation with the same industrial perforation, the first achieves a
higher perforation efficiency; this can be justified by looking at Figs. 7(b) and 7(c),
respectively. Figure 7(c) shows a thinner and less marked cut, without affecting the fibrous
structure adjacent to the cut. In contrast, Fig. 7(b) shows a thicker and more marked cut,
weakening the structure nearby the cut. To achieve the same perforation efficiency of the
industrial 3 mm cut, a 3.5 mm cutting blade would need to be used. Therefore, to equalize
the efficiency of industrial perforation with laboratory perforation the cut distance of the
laboratory blade must be increased 15% when compared to the industrial cut distance.
In addition to the qualitative comparison of industrial and laboratory cuts, Fig. 7
illustrates the sequence of all cut distances (2 mm to 8 mm) that were laboratory performed
in this work, keeping the blank distance constant (1 mm).
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Fig. 7. Optical images of the different laboratory cut distances for the BP2 toilet paper and the
industrial perforation for the same toilet paper
Figure 8 compares the industrial and laboratory perforations in different
commercial toilet papers from the measurements of the cuts by the optical system.
Analyzing this figure, it is confirmed that the dimensions of the laboratory cuts are always
smaller than the industrial ones. In addition, both types of cut are inferior to the target
measure.
Fig. 8. Comparison of industrial vs laboratory cut distances for different toilet papers
In agreement with what was previously presented in Fig. 4, the stabilization for a 6
mm laboratory cut, and because this cut was inferior to the industrial one, it can be assumed
that industrially this stabilization will occur for a 5 mm industrial cut. In brief, industrially,
the maximum cut to obtain an optimized perforation efficiency without impairing the
runnability of the converting machine is 5 mm. Of the analyzed papers, the one with the
best perforation efficiency was a 4-ply paper with a cut distance of 5 mm (MP4). The
findings of this study suggest that the fibrous composition and the number of plies had a
small contribution in the perforation efficiency results. The cut distance had the biggest
impact in the results of the perforation efficiency.
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CONCLUSIONS
1. The optimization of the perforation efficiency was obtained for a 6 mm laboratory cut
distance, corresponding to an industrial cut distance of 5 mm.
2. The evidence from this study suggests that the major impact on perforation efficiency
is related to the dimensions of the perforation cuts and not the fibrous composition and
number of plies of the toilet paper samples.
3. In general, the results of the finite element method (FEM) simulation analysis support
the idea that the value of perforation efficiency tends towards an establishment from a
specific cut distance of 6 mm.
4. The described laboratory approach applied to this set of samples, has the potential to
explain the perforation behavior on the converting machine, although for that a blade
with a cut distance 15% higher than the industrial cut distance must be used.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the funding of this work that was carried out
under the Project InPaCTus – Innovative Products and Technologies from Eucalyptus
(Project Nº 21874) funded by Portugal 2020 through the European Regional Development
Fund (ERDF) in the frame of COMPETE 2020 nº246/AXIS II/2017.
The authors are also very grateful for the support given by research unit Fiber
Materials and Environmental Technologies (FibEnTech-UBI), on the extent of the project
reference UIDB/00195/2020, and by the Center for Mechanical and Aerospace Science and
Technologies (C-MAST-UBI), on the extent of the project reference UIDB/00151/2020,
both funded by the Fundao para a Cincia e a Tecnologia, IP/MCTES through national
funds (PIDDAC).
REFERENCES CITED
Baggot, J., Gropp, R. F., and Wojcik, S. (2006). “System and method for severing or
perforating a web,” U.S. Patent No. 2006/0014616.
Bennett, H. (2009). “Ever wondered about the history of toilet paper?,” Washington Post
(http://www.washingtonpost.com/wp-
dyn/content/article/2009/05/31/AR2009053102217.html), Accessed 14 July 2019.
Chih, C.-K. (2018). “Perforation design & calculation of toilet paper rewinder,” China
Pulp and Paper 37(9), 38-42. DOI: 10.11980/j.issn.0254-508X.2018.09.007
Haggith, M., and Martin, J. (2018). The State of the Global Paper Industry, The
Environmental Paper Network (EPN), Asheville, NC, USA.
ISO 187 (1990). “Paper, board and pulps - Standard atmosphere for conditioning and
testing and procedure for monitoring the atmosphere and conditioning of samples,”
International Organization for Standardization, Geneva, Switzerland.
ISO 12625-1 (2019). “Tissue paper and tissue products - Part 1: Vocabulary,”
International Organization for Standardization, Geneva, Switzerland.
PEER-REVIEWED ARTICLE bioresources.com
Vieira et al. (2022). “Toilet paper perforation efficiency,” BioResources 17(1), 492-503. 503
ISO 12625-12 (2010). “Tissue paper and tissue products - Part 12: Determination of
tensile strength of perforated lines - calculation of perforation efficiency,”
International Organization for Standardization, Geneva, Switzerland.
Mendes, A. O., Fiadeiro, P. T., Costa, A. P., Amaral, M. E., and Belgacem, M. N. (2013).
“Retro-diffusion and transmission of laser radiation to characterize the paper fiber
distribution and mass density,” in: Proceedings Volume 8785: 8th Ibero American
Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and
Applications, Porto, Portugal, pp. 8785AY-1/8785AY-8. DOI: 10.1117/12.2022367
Mendes, A. O., Fiadeiro, P. T., Costa, A. P., Amaral, M. E., and Belgacem, M. N. (2014).
“Study of repeatability of an optical laser system for characterization of the paper
fiber distribution and mass density,” in: Proceedings Volume 9286: Second
International Conference on Applications of Optics and Photonics, Aveiro, Portugal,
pp. 92862Y-1/92862Y-8. DOI: 10.1117/12.2062697
Mendes, A. O., Fiadeiro, P. T., Costa, A. P., Amaral, M. E., and Belgacem, M. N. (2015).
“Laser scanning for assessment of the fiber anisotropy and orientation in the surfaces
and bulk of the paper,” Nordic Pulp & Paper Research Journal 30(2), 308-318. DOI:
10.3183/npprj-2015-30-02-p308-318
Mukai, T., and Shimizu, Y. (2003). “Toilet paper roll with perforated line,” JPO Patent
No. 2003061861A.
Ogg, R. G., and Habel, M. A. (1992). “Perforator blade for paper products and products
made therefrom,” U.S. Patent No. 5114771.
Olson, S. R., Hoadley, D. A., and Daul, T. A. (2016). “Partitionable paper towel,” U.S.
Patent No. US20160345786A1.
Schulz, G., and Gracyalny, D. (1998). “Method and apparatus for pinch perforating
multiply web material,” U.S. Patent No. 5755654.
Shiang, T. T. (2012). “Tissue paper cutting mechanism having upper knife with variable
spiral curve angle and upper knife structure therefor,” EPO Patent No. EP2095917B1.
Skene, J., and Vinyard, S. (2019). The Issue with Tissue: How Americans are Flushing
Forests Down the Toilet (R: 19-01-A), Natural Resources Defense Council and
Stand.earth, New York, NY, USA.
Vieira, J. C., Vieira, A. C., Mendes, A. O., Carta, A. M., Fiadeiro, P. T., and Costa, A. P.
(2021). “Mechanical behavior of toilet paper perforation,” BioResources 16(3), 4846-
4861. DOI: 10.15376/biores.16.3.4846-4861
Wheeler, S. (1894). “Wrapping or toilet paper,” U.S. Patent No. 511983A.
Article submitted: August 6, 2021; Peer review completed: October 17, 2021; Revised
version received and accepted: November 18, 2021; Published: November 24, 2021.
DOI: 10.15376/biores.17.1.492-503
