dk nkf - Nordisk Konservatorforbund Danmark

% of objects
100
90
80
70
60
50
40
30
20
10
0
1800-1809
1810-1819
1820-1829
1830-1839
1840-1849
1850-1859
1860-1869
1870-1879
1880-1889
Fig. 3. Proportion of brittle paper in The Royal Library 1800-1985. The columns are subdivided according to hand folds to give a more
nuanced picture of the state. We find lignin in the paper at The Royal Library from 1870 and onwards.
to Drott [4]. The results from measuring the individual
samples can be used to describe the entire library
collection from 1800-1985 because the sample is
representative of the whole population. Measured
parameters were pH (micro cold extraction), colour
(CIELab), brittleness (hand fold), lignin, thickness
and weight.
The survey [5] revealed that the total quantity of
material from the period 1800-1985 is 1,498 tons of
paper corresponding to around 1.3 millions objects.
As many as 93 % of the Royal Library’s objects from
the period are more or less acidic and therefore retain
a much shorter life than rag paper sized with gelatine
made before the industrialization. This corresponds
to what other international studies reports.
About 7 % of the objects from the period investigated
are already very brittle (defined as the paper corner
breaking in three hand folds or less), and thus at risk
by common use. This part of the collections is not
subject to mass deacidification as the objects are
already too brittle. In fig. 2, a very brittle newspaper
is illustrated. To rescue the information in such an
object reformatting into another media is required.
In fig. 3 the proportion of brittle papers is presented
in relation to their year of manufacture. There are
1890-1899
1900-1909
Period
1910-1919
1920-1929
1930-1939
significant differences in the proportion of brittle
paper in the different decades corresponding to the
materials used in the historical production. Thus,
there is no single linear relationship between an
object’s age and degradation rate.
The figure shows that the proportion of brittle paper
up to 1830 is below 10 %, after which it rises up to
40% in the 1840s. In the 1850s the proportion of brittle
paper decreases to just over 10 %. After this, there is
a strong continuous increase until the 1890s, where
the proportion of brittle paper reaches over 80 % of
the objects. In the following decades, the proportions
of brittle paper fall for each decade until the 1970s,
after which virtually no brittle paper is found in the
collections.
Lifetime – pH
Degraded (7-12 hand folds)
Brittle (4-6 hand folds)
Very brittle (