hp media results
archivable papers:
a report on acid-free
and lignin-free paper
Table of contents
Executive summary .......................................................................................... 3
Introduction ................................................................................................... 5
Papermaking terms and definitions ...................................................................... 6
Paper preservation 鈥? Where are we now? .......................................................... 6
Confused state of information ............................................................................ 6
Conclusion .................................................................................................. 10
For more information ..................................................................................... 10
漏 2003 Hewlett-Packard Company
HP and the HP logo are property of Hewlett-Packard Company. All other brands and their products are
trademarks or registered trademarks of their respective holders.
Specifications subject to change without notice.
media results 2 February 2003
archivable
a report on
acid-free and papers
lignin-free paper
a report on acid-free and lignin-free paper
Executive summary
The field of paper preservation is constantly changing as new papers are developed and paper
manufacturing evolves. Developing new and specialty papers for inkjet printers has created a need
to understand the factors tha t determine if the paper can be archived.
Many consumers are becoming aware of buzzwords like 鈥渁cidity鈥? and 鈥渓ignin鈥? content (see
Papermaking terms and definitions on page 6), and they unders tand that these words refer to
factors that somehow reduce the longevity of paper. Consumers are also confused by the
conflicting messages from paper manufacturers regarding how acid and lignin affect the
preservation of paper and the text or images printed on the paper. In addition, a multitude of
paper industry organizations use varying standards regarding the effects of acid and lignin on
paper preservation. As a result, consumers have many questions about claims that paper is acid-
free and lignin-free, including:
What are these claims based on?
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How long will the document or photograph remain unaffected?
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What other factors influence the permanence of documents and photographs?
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As the leader in the field of photo and specialty papers for inkjet printers, Hewlett-Packard鈥檚 (HP)
position on acidity and lignin content is needed to provide clarity in a confused marketplace. HP
recognizes the traditional claims made by the paper industry concerning acid-free paper are based
on the alkaline process used to make the base paper (substrate), but does not consider coating that
is added to the paper.
In the past, many pulping processes used strong acid treatments to separate the lignin from the
cellulose fibers; this created papers that degraded rapidly. As a result, the traditional definition of
acid-free paper began to be used to describe papers made by non-acidic papermaking processes;
these acid-free substrate papers were less likely to degrade with age. Acid-free materials were
considered safe for contact with other materials since they would not cause acid-related
degradation. Therefore, 鈥渁cid-free paper鈥? became a traditional term synonymous with long-lasting
or archival-quality paper.
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Unfortunately, the traditional definition of acid-free paper may have limited application to many
modern coated papers designed for printing purposes and image preservation. Modern papers
often use no strong acids in the papermaking process, but may use weak acids in the coating
process. These weak acids do not necessarily increase paper degradation, but they do affect the
pH value (see Papermaking terms and definitions on page 6) of the paper. Therefore, modern
papers may or may not meet the traditional definition of acid-free, but could still be suitable for
archival purposes.
A vast majority of HP photo and specialty papers for inkjet printers meet the traditional definition of
acid-free and lignin-free because their substra tes are produced by alkaline processes and they
contain no more than one percent lignin (see Figure 1 on page five). While these papers p rovide a
competitive solution for archiving photos and valued documents, HP believes the question of
archivabili ty is complex and has not been treated with the proper level of sophistication. HP also
concurs with the recommendation of the Interna tional Standards Organization (ISO) that paper
marketed as lignin-free should contain no more than one percent lignin.
In an effort to help the industry redefine or replace the term 鈥渁cid-free,鈥? HP is continuing aging-
simulation studies to provide a better understanding of how modern paper permanence is affected
by lignin, various types and amounts of coating acids, and other archival factors. HP鈥檚 dedication
to paper permanence research is a reflection of their commitment to produce the best photo and
specialty papers for inkjet printers.
HP papers
The following table is a comparative listing of the acid-free papermaking process and lignin content
for many of HP鈥檚 photo and specialty papers for inkjet printers.
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For an explanation of some of the key papermaking terms, see Papermaking terms and definitions
on page 6.
Product Name * Meets traditional industry definition of acid-free? ** Lignin- free?
HP Premium Plus Photo Paper, Glossy Yes Yes
HP Premium Plus Photo Paper, Matte Yes Yes
HP Premium Plus Photo Paper, Glossy Yes Yes
(4 x 6)
HP Premium Photo Paper, Glossy Yes Yes
HP Photo Paper, Glossy No Yes
HP Everyday Photo Paper, Semi-Gloss Yes Yes
HP Everyday Photo Paper, Matte No Yes
HP Textured Greeting Cards Yes Yes
HP Photo Greeting Cards, Half-fold No Yes
HP Brochure and Flyer Paper, Gloss Yes Yes
HP Brochure and Flyer Paper, Matte No Yes
HP Premium Inkjet Paper No Yes
HP Premium Inkjet Heavyweight Paper No Yes
* Manufactured using an alkaline process.
** Lignin content of no more than one percent.
Figure 1: Acid-free and lignin-free designation chart
Introduction
Long before modern printing technologies were developed, people noticed that different types of
paper suffered various types of aging such as discoloration and loss of strength. At that time, the
difference in aging behavior was largely caused by the different types of pulping methods that
were used to convert the raw material (wood, cotton, or other materials) to a pulp tha t was then
formed into paper.
In determining the aging of modern papers, the pulping process is only one consideration. Other
key factors鈥攊ncluding the acidity of the ink, substrate and coating; the storage conditions; and the
lignin content of the paper鈥攁lso affect the longevity of modern papers. This report deals primarily
with two of these key variables associated with paper permanence:
What percentage of the lignin remains in the paper?
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What residual acids, if any, remain in the paper substrate and coating layers?
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This report also discusses key papermaking terms, paper preservation standards, pH tes ting, and
the role of lignin and acid content in paper archivability.
Papermaking terms a nd definitions
This section defines key papermaking terms.
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Acid, as it applies to papermaking, is a water-soluble compound that can be present in paper
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as a result of the papermaking process. In the presence of moisture, acid may cause paper to
degrade.
pH is a symbol that represents the acidity or alkalinity of a substance. A neutral solution has a
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pH value of seven. The pH value drops toward zero as the acidity increases and rises toward
14 as the alkalinity increases.
Coated paper is any type of paper to which a surface coating has been applied in order to
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enhance appearance and printability.
Kraft (alkaline) process is the most common chemical pulping process. It uses alkaline-based
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chemicals鈥攔ather than acid-based chemicals鈥攖o separate the lignin from the wood fibers.
Lignin is a brown organic substance that binds to cellulose fibers and hardens and strengthens
鈥?
the cell walls of plants. Lignin is the chief non-carbohydrate constituent of wood and is also a
major contributor to the chemical degradation of paper. As it deteriorates, lignin gives off
acids that cause paper to become brittle and to discolor on exposure to heat and light.
Paper preservation 鈥? Where a re we now?
The paper industry and paper consumers are interacting constituencies whose goals and roles are
quite different, yet both a re trying to keep up with a complex and evolving industry. This section
explains the present outlook of the paper industry and consumers in regards to paper preservation.
The paper industry, including paper manufacturers, has created many organizations to establish
paper specifications, standards, and test methods. These organizations sometimes undermine the
validity of one another by using different criteria that yield dissimilar conclusions.
Consumers simply want long-lasting documents and photographs, and seek what they hope is
helpful information by asking questions like, 鈥淚s this acid-free?鈥? Industry leaders such as HP have a
responsibility to not only provide answers to questions like this, but perhaps more importantly, to
educate the consumers about other information regarding storage conditions, types of ink, and
coatings that may be more relevant to the fundamental ques tion 鈥渉ow long will my documents and
photos last?鈥?
Confused state of information
The facts regarding paper permanence can dissolve into a complex morass of marketing claims.
HP鈥檚 competitors have made claims based on varying standards set by the paper industry.
Consumers make paper-purchasing decisions based on these claims with only limited knowledge
regarding the complex subject of modern papermaking and paper permanence.
Although paper manufacturing methods have evolved, and new specialty papers for inkjet printers
have augmented the paper selection beyond uncoated papers, consumers still associate any
preservation issues with buzzwords such as 鈥渁cid-free鈥? and 鈥渓ignin-free.鈥? However, since these
terms originated before the advent of modern coated papers, the terms have diminished relevance
to the subject of modern paper archivability.
The uncertainty that exists among both consumers and suppliers regarding paper permanence has
to do with the following factors:
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Varying industry standards
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Ambiguous marketing claims
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The complex interaction of new inks
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Changing papermaking techniques
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The impact of environmental factors such as storage temperature and humidity
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The various types of acid, including very weak acids, used in modern paper coatings
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The ramifications of acids on the archivabili ty of paper
鈥?
What acid-free and lignin-free mean to the paper industry
It is important to note that the traditional paper industry considers paper permanence to be the
result of optimizing multiple paper properties, two of which are pH level (acidity) and lignin
content. Therefore, specific information about acidity and lignin content is almost always nested
within discussions and standards for paper permanence.
In the paper industry, acid-free paper is often tied to longevity. For example, according to
International Paper鈥檚 Pocket Pal, creating an acid-free paper is defined as a 鈥減rocess that gives
paper over four times the life (200 years) of acid-sized paper (40-50 years).鈥? 1
The following organizations have established the following paper specifications, standards, and
test methods:
National Information Standards Organization (NISO)鈥?(ISO 9706 and ISO 11108)
鈥?
American National Standards Industry (ANSI)鈥?(ANSI Z39.48 鈥? revised 1997)
鈥?
International Organization of Standardization (ISO)鈥?(ANSI Z39.48 鈥? revised 1997)
鈥?
Technical Association of the Pulp and Paper Industry
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Library of Congress (Preservation Directorate: Progress on Monitoring Pub. L)
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Based on the ANZI Z39.48 standards, for example, the paper industry defines paper permanence
for uncoated or coated writing or printing papers based on a pH value between 7 and 10鈥?(from
a cold-water extract) and a lignin content of no more than one percent.
What acid-free and lignin-free mean to paper manufacturers
A survey of consumer Web sites and calls made to customer service centers of eight leading
companies reveals a blur of information about the definition of acid-free and lignin-free paper. The
Web site for each company was researched for information related to acid-free and lignin-free
paper. In addition, the customer service departments were asked which of their papers were acid-
free and most suitable for printing photos at home.
Much of the information offered to consumers by customer service representatives is marketing
driven rather than scientific. Many representatives used buzz words like 鈥漚rchival鈥? and 鈥渁rchival-
safe鈥? regarding acid-free claims, but they could not answer more detailed questions regarding
Pocket Pal, Memphis, TN: International Paper, 2000.
1
media results 7 February 2003
testing standards, coating acids, or manufacturing conditions. Most of the company Web sites do
not list their papers or make definitive claims regarding their papers鈥? acidity or lignin content.
What acid-free and lignin-free mean to consumers
Millions of consumers who are interested in acid-free and lignin-free paper want to print their
photos at home for archival purposes. In their search for paper, they often receive stern guidelines
and warnings from third-party suppliers about the need for acid-free paper. Unfortunately, this term
can cause confusion and has limited application when applied to many modern papers used for
printing or image preservation purposes.
The major advocates of acid-free and lignin-free paper are companies that sell products to
genealogists and home historians. Numerous Web sites, such as creativememories.com (a popular
scrapbook supplier) are convincing consumers that 鈥済enerations yet unborn鈥? will cherish their
scrapbooks only if archival-quality paper is purchased from a qualified conservation supplier.
Other Web sites insist that the only reliable way for consumers to determine the acidity level of a
paper is to purchase a pH test pen and test the paper using the pen.
Numerous tests by HP concluded that the most commonly available 鈥榩H test pens鈥? yielded
conflicting results depending on the brand of the tes t pen. Thes e tes ts also gave misleading
information such as the indication that some coated papers contained acid when in fact they did
not. If archivability standards were better defined and applied, consumers would only need to refer
to the manufacturer鈥檚 specifications and not rely on third party suppliers.
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Adding to the confusion is the fact that many consumers have a limited understanding of the
following paper information and characteristics:
Modern papers are often an intricate composition of base paper (substrate) and coating(s) on
鈥?
which the ink is deposited. Figure 2 shows one example of the intricate layering struc ture of
modern coated paper.
Figure 2: An example of the intricate layering structure of modern coated paper.
Both the base paper and the coating can have acidic or other properties that may cause
鈥?
degradation. For this reason, the acidic content of the coating is just one critical factor in
image and text preservation. Therefore, merely describing the acidic properties of the base
paper or just testing the acidic properties of the coating with a pH test pen is not necessarily a
comprehensive way to judge the permanence of modern papers.
Paper archivability is not well defined by the term 鈥渁cid-free鈥? and should be replaced by a
鈥?
term more capable of predicting the longevity of modern papers.
Archival quality paper
Ultimately, consumers are most concerned with the archivability of their documents and
photographs. However, acidity and lignin levels are not the only archivability factors. Other factors
that influence paper longevity include the following:
The permanence of the inks
鈥?
The humidity and temperature (or the fluctuation of temperatures) in storage
鈥?
External contacts with the paper such as other papers, dust, and excessive light
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Furthermore, a ll these factors are grea tly affected by the specific characteristics of the paper, such
as the weight of the paper, whether the paper has a coating, what type of coating is present along
with the acid and lignin content of the paper.
media results 9 February 2003
Conclusion
Consumers are understandably very devoted to preserving their valuable documents and
photographs. According to the Photo Marketing Association International (PMAI), in 2002,
Americans took approximately 55 million photos per day or more than 20 billion photos per year.
Over 75 percent of Americans try to preserve their memorable photographs by putting them into
scrapbooks and albums.
For millions of consumers, the introduction of complex contemporary photo and specialty papers for
inkjet printers has complicated the issue of paper archivability.
HP鈥檚 position on acid and lignin content is needed to help clarify the current confusion in the
marketplace. Therefore, HP lists its own papers in a paper permanence table (see Figure 1 on page
5) and issues the following position on paper permanence:
Lignin-free paper 鈥? HP supports the recommendations of the ISO/ANSI Z39.48 standard that
鈥?
paper marketed as lignin-free should contain no more than one percent lignin.
Acid-free paper 鈥? Since there is no definitive scientific linkage between surface coating pH
鈥?
results and paper archivability, HP believes the traditional term 鈥渁cid-free鈥? needs to be
redefined or replaced by another measure that better predicts archivability. As an interim
solution, HP is providing the information contained in Figure 1.
Commitment to testing 鈥? HP is committed to serving its customers by conducting ongoing
鈥?
aging simulations for several representative papers in its product line.
Commitment to consumers 鈥? HP is committed to providing consumers with a clear message
鈥?
and tested res ults on the effects of acidity, lignin content, and all other archival factors
regarding the preservation of current and future papers as well as educational documents such
as this report.
Commitment to development 鈥? HP is dedicated to exploring new paper technologies in order
鈥?
to produce the best photo and specialty papers for inkjet printers.
For more information
To understand how to interpret display-permanence predictions and the factors that affect how long
a print will last, see 鈥淗P Inkjet Photo Prints : Memories for Generations鈥? at:
http://www.hp.com/sbso/product/supplies/more_media_tech.html.
Christi Putz
Media Content Integration Team
208.396.4872
www.hp.com
Hewlett-Packard Company
Copyright 漏 2003
media results 10 February 2003
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