Скачать или смотреть Malešič et al Evaluation of Various Test Strips IADA2025

Copper ions in paper-based objects originate from
pigments such as verdigris or malachite, as well as from
inks like iron gall, which can also contain metals such
as copper, aluminum, and chromium. While various
analytical techniques can detect these ions, they are
often unavailable to conservators in private or small
workshops. To address this, Neevel developed simple
‘iron tests’ for detecting free Fe(II) and Fe(III) ions,
which are now commercially available. He also created
tests for copper ions, but these remain inaccessible on
the market. As a result, conservators rely on products
like Cuprotesmo or prepare their own tests, though
many were not designed or validated for paper
applications. Accurate copper detection is essential
for selecting proper conservation treatments and
preventing further degradation. This study compared
three copper detection tests for paper. Model samples
were prepared by immersing Whatman filter papers in
copper sulfate solutions at concentrations ranging from
0.050 ± 0.006% to 7.9 ± 0.3% copper-to-paper ratios,
verified by atomic absorption spectroscopy. Potential
interference from Fe, Mn, Cr, Co, Ni, Zn, K, Ca, and
Mg was evaluated using metal mixtures applied to the
paper. Additionally, the tests were applied to sacrificial
historic papers containing verdigris or iron gall inks,
with copper presence confirmed via X-ray fluorescence.
Results indicate that test papers prepared using Hulthe’s
method exhibited the lowest detection limits, minimal
metal interference, and the least discolouration—
making them the most suitable for application on
cultural heritage papers.