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30
Newsletter
PFI Participates in Wet-White Round-Robin Test
Mould Resistance of Leathers
and Intermediate Products
Round-Robin Test Procedure
The original method was updated on the basis new
findings and experience gained by the participants.
The experts agreed to adopt a number of modifications,
such as optimisation of the culture conditions
and prolongation of the incubation time from 21 to
28 days while retaining weekly evaluation. In addition,
the range of test organisms was extended to include
Hormoconis resinae, which can cause material damage
and is frequently found on leather products. The range
of test microorganisms thus comprises: Aspergillus sp.,
Penicillium sp., Trichoderma viridae, and the abovementioned
Hormoconis resinae. Use of a mixture of
fungal spores (as in the original methods) was categorically
excluded in the interest of obtaining reproducible
microbiological results. Determination of the
Mould resistance towards Penicillium sp. after
seven days; inhibition zone formation in the case of
treated samples (b to d)
MICRoBIoLoGY
bioburden and internal controls on untreated samples
were also considered in revision of the procedure.
Samples for the round-robin test were provided
by Südleder GmbH & Co. Tests were performed on
samples without active substance and with four
different concentrations of the mould inhibitor
2-(thiocyanomethylthio)benzothiazole (TCMTB). The
content of active substance was determined at the Research
Institute for Leather and Plastic Sheeting (Forschungsinstitut
für Leder und Kunststoffbahnen, FILK),
which also participated in the round-robin test.
a b c d a b c d
Mould resistance towards Aspergillus niger, untreated
samples are completely covered by mould growth (a)
and samples with a low degree of preservation only at
the edges (b). Samples with a higher concentration of
active substance exhibit adequate mould resistance (c, d).