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Round-Robin Test Methodology
The method is based on an agar diffusion test. Punched
out specimens are placed with both the flesh side and
the grain side in contact with an agar plate uniformly
inoculated with spores of a given test organism and
incubated at elevated temperature and moisture levels.
The test organism, a mould fungus, then grows
initially on the agar and, depending upon the state of
preservation, possibly also on the specimen. The condition
of the sample is evaluated on a weekly basis.
Any inhibition zone appearing around the specimen is
recorded and measured.
If there is a lack of mould resistance (evaluation 1/A, A
= growth area) mould growth generally begins at the
outer edge and gradually proceeds over the test sample;
the extent of growth was also measured.
If preservation is adequate the samples will show no
mould growth (evaluation 0/0) at the end of the incubation
period or possibly also an additional zone devoid
of fungal growth immediately surrounding the
samples (evaluation 0/H, H = extent of inhibition zone
in mm) and the material thus fulfils the demands of
stability toward mould growth over this time interval.
01.2011
Magazine of the Test and Research Institute Pirmasens
Test samples, glutaraldehyde tanned „Wet white“
Control plates with various test organisms (left to
right): Aspergillus niger, Penicillium sp., Trichoderma
viridae, Hormoconis resinae
a b c d
Mould formations due to bioburden, outer left on
untreated samples (a); samples with three different,
increasing concentrations of an active substance
(right, b to d) exhibit mould resistance
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