[Table of Contents] [Search]


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Question about Decay



<
1) What kinds of trees are used in book publishing?
        Are there certain choice spots around the world
        or the U.S.A. for selecting the trees used for publishing?
>
Conifers (pine, spruce, fir, etc.) are most used. Some hardwoods are
also used in smaller proportions. Trees come from many places. The
northeast and northwest parts of the US as well as Canada are
sources. Huge tree plantations in South America also provide wood.
There are many other places as well that are too numerous to
mention here.

>
2) Approximately what % or parts of a tree are used for publishing
>
Trees are commonly harvested by large machines that seize the tree
in huge claws. The tree is sheared at ground level, stripped of its
branches and loaded onto a truck. Trees are then taken to the mill
where they are cut into 4 ft lengths and the bark is removed. What is
left is turned into wood pulp.


>
How old can a book be before its cover or pages begin
to deteriorate? What causes the deterioration?
>

Books have survived from weeks to centuries depending on type of
paper used. Older books used paper made from rags (cotton). This
paper is usually very stable. More modern books, starting in the
19th century used wood pulp. The stability of wood pulp paper can
vary greatly.

If the wood pulp is prepared by grinding against huge
grinding wheels it is called groundwood. This is most efficient and
provides the greatest yield. The pulp is bleached and used in cheaper
books (sometimes called pulp fictions, etc.). In this process the
glue-like substance called lignin that bonds the fibers together is
not removed, only made colorless. Unfortunately, the lignin begins
to revert to its natural color soon after manufacture. That is why
books and newspapers that use groundwood yellow with time.

A less efficient, more costly process chips the logs into chips
that are sent to large vessels where they are cooked with various
chemicals to dissolve the lignin and free the individual fibers. The
type of chemicals, length of cook, and type of wood have impact on
the ultimate stability of the paper. The longer the cook, the
greater the proportion of lignin and more soluble celluloses are
removed from the wood until only the purest fractions (and most stable)
fractions remain. This is basically a tradeoff between cost and
stability.

The pulp is then washed and bleached with various compounds. The
type and length of bleach cycles also impact ultimate paper
permanence.

Paper began its slide into rapid degradation in the late 18th century
when bleaching compounds began to be used without understanding the
long-term consequences. This rapidly accelerated in the mid 19th
century with chemicals that left an acidic paper that was prone to
quickly degrade. Environmental effects like air pollution also
had a negative effect on permanence of paper. Sulfur and nitrogen
compounds in the air combined with moisture in the paper to form
cellulose-eating acids. More modern papers usually are less acidic
or even on the basic side of pH and are more stable.

>
Are there certain microbes or other natural organisms that eat away
at the book?
<
Yes, many. =


>
What conditions are needed to preserve a book from deterioration?
<
If the paper is acidic it can be neutralized with special sprays. The
Relative humidity should be between 30 to 60% for optimal keeping.
Prevent light and air pollutants from reaching the book. The lower
the temperature, the better.


Most librarians can probably point you to books in their collections
that provide much more information on book care.

Dick Grant

             ***********************************************
            BOOK_ARTS-L: The listserv for all the book arts.
      For subscription information, the Archive, and other related
            resources and links go to the Book_Arts-L FAQ at:
                      <http://www.philobiblon.com>
             ***********************************************


[Subject index] [Index for current month] [Table of Contents] [Search]