Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed
År: 1909
Sted: Kjøbenhavn
Sider: 185
UDK: 6201(09)
On the development of testing of materials in the north and on the work of the danish states testing laboratory in Copenhagen (english translation)
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168
to coloured cement planes, being at the same time instrumental in
rendering the plaster tight. The named report treats further of
the researches made by the Laboratory to find suitable pigments
to mix up with cement mortar, as it is well known that many
pigments are destroyed by this intermixture.
The researches were made at the Testing Laboratory by a
sub-committee consisting of the gentlemen named in Note 1, p.
167, and elected by the committee, and this sub-committee had
various restoring experiments made on loose flakes, among these
in the spring of 1900 a larger sample of the pictorial represen-
tation containing 8 various sorts of coloured plaster. This sample
was able to stand all through the summer in sunheat and rain
without cracking and, it is true, that in the following winter a
great many very fine fissures occurred in 3 of the 8 sorts of
coloured plaster, but the 5 others were exposed to the sunshine
and rain of 3 summers and the frost of 2 winters i. e. to up to
about 50° Centigrade and down to 12—13° Centigrade below
zero without cracking and without the named fine fissures in-
creasing apparently in number or size.
A restoring trial was later made by the magistracy of Copen-
hagen by much the same method on the museum itself at the
ordinary entrance. But bad fissures soon occurred here. The
reason can be sought for in various circumstances, for instance
in the intermixture of pigments having not been the same, in the
hardness of the smoothing having differed, or in some contrac-
tion of the decoration having taken place while the experiment
was made with the loose flake, this not having been discovered
by formation of fissures, because perhaps the flake itself has
also contracted. The very difficult problem has therefore not
yet been solved, but in one direction, at any rate, there seems
to be a reliable result, as series of durable pigments having na-
mely been found.
g. Experiments with Partly Replacing Lime in Lime-Mortar
by Moler.
At the first series of experiments a mortar was be-
gun with which contained 8 per cent dry calcic hydrate. As
sand was used a mixture in equal proportions (by weight) of
normal sand and down sand. In the named mortar the half-
part of the calcic hydrate was then replaced by moler.