Paper Conservation: Decisions & Compromises

Simple yet Complicated – An Evaluation of Airbrush Technique
Applied to Filling Losses using Cellulose Powders
xing kung liao | fei wen tsai
Tainan National University of the Arts, Tainan City, Taiwan
Introduction
Filling losses is a very common practice for paper-based
artifacts. This can be performed either
by machine using a leafcaster, or it can be done
manually, which can be very labor intensive.
Many methods have been designed to achieve filling
purposes depending on the nature and the
condition of the paper objects. Considerations to
be observed in filling or compensation of paperbased
materials include the character and thickness
of the paper object, the quality of the filling
materials and the properties of the adhesives, as
well as compatibility issues between the paper
artifact and filling materials, etc.
In general, filling materials used for this purpose
include paper pulp and cellulose powder.
Paper can be inserted to compensate for losses
using western paper or bast fiber paper, also
known as Japanese paper. Paper pulp is another
filling material; it could be applied in numerous
irregular-shaped loss areas of an artifact if the
object can tolerate wet treatment. The paper insert
method is mainly performed manually, and
paper pulp can be applied manually with the
help of a suction disc or performed mechanically
using a leafcaster. Both paper and paper pulp as
mentioned above are the most commonly repair
Fig. 1: After Mapping the Areas to Be Filled
materials for filling applications (Paper Conservation
Catalog, 2011).
Another filling material – cellulose powder
– is also recorded in conservation related literature.
It can be used to fill small losses by adding
water to powder to form a paste and then applying
it to loss areas. One concern about the use of
cellulose powder as a filling material is its flexibility
after application. In addition, the difficulty
of applying cellulose powder evenly is also one
of the disadvantages of using it as a filling material.
To avoid uneven application, spraying might
offer a viable alternative when using cellulose
powder to compensate losses.
The spraying method has been adopted as one
of treatment techniques for in-painting, humidification
and consolidation/fixing, as well as for
applying a protective coating layer on the surface
of an object (Webb, 1998). This can be done by
using various tools such as air mist, a Dahlia
sprayer, airbrushes or other methods. Among
these spraying tools, the airbrush can yield an
even coating for treatment purpose. This paper
evaluates an alternative method of filling losses
using stable and reversible cellulose powders
and airbrush techniques that is regularly used in
Asian painting conservation.
The airbrush applicator
The invention of the airbrush is attributed to
Francis Edgar Stanley, who patented the first
airbrush in 1876 (Patent Number 182,389). His
invention was not used for art works, however,
up until 1879 when the first “airbrush” instrument
with a hand-operated compressor used for
painting-related purposes was developed by Abner
Peeler. At that time the airbrush was not at
all sophisticated, and it took four more years of
development to refine the airbrush device which
was marketed by Liberty Walkup.
An airbrush works basically by passing a
stream of fast-moving (compressed) air through a
Venturi, which reduces the air pressure (suction)
to allow liquid or paint to be pulled from an interconnected
reservoir. The high velocity of the
ICOM-CC Graphic Documents Working Group Interim Meeting | Vienna 17 – 19 April 2013
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