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This report describes the evaluation of five classes of
materials as possible replacements for the lead driers used in a
cobalt-lead-calcium drier system.
The materials investigated were metal driers, metal amines,
oxygen carriers, one electron oxidising agents and enzymes.
Drying time tests were carried out on selected commercial paints
representative of commercial production in the 1980's and were
supplied with and without drier addition.
The tests were carried out on the drier-free commercial paints
after addition of alternative drier systems. The fully formulated
commercial paints served as the controls. The testing schedule
involved measuring the drier performance at low temperature and
high humidity as well as determining colour.
The most promising lead drier replacement was judged to be
copper naphthenate. The principal disadvantage is that drying
efficiency decreases on paint storage.
Loss of dry problems are not unfamiliar to the industry and
can be minimised by minor formulation changes. One possibility is
to use an excess of calcium drier and to add this during the
milling stage in order that it can be adsorbed in preference to
copper.
Further Information
If you are interested in this, or any other project, please contact Richard Holman.
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