evaporating surface. Initial filter drying is necessary only in case of
measurements which require very high accuracy.
Substances with structure of leather or temperature sensitive
In case of such substances it is proved to a glass fibre filter. While testing, a
substance is placed on a drying pan, and sample surface is covered with a filter,
which protects the sample from direct heat radiation. In such case, the sample is
heated by convection (which is milder than radiation).
Substances containing sugar
The surface of such substances often may
caramelize during testing procedure. Therefore, it is
recommended to use thin layer of a sample, and
moderate drying temperature.
17.1.3. Sample distribution on drying pan:
Loose materials
Dried in their natural state, i.e. in their natural
form or disintegrated. Sample disintegration causes
smaller dispersion between the following
measurements. Sample mass should not be too high,
and the sample should be evenly spread on whole
surface of the drying pan.
Liquid substances
Semi-fluid substances are dried in their natural
form. Large amount of grease (fat) occurring in
some of substances makes moisture content
determination difficult. In such case it is
recommended to use additional components, which
increase sample’s active surface and aid moisture
content releasing process from a sample. Such
components are high silica sand, blotting paper or
filter. Before drying a tested substance, initially dry
the additional component, so that its humidity is
close to zero.
Solid objects
Depending on solid object’s structure (dense or loose), moisture content
determining process may take short or long time. The size of solid’s surface
determines the speed of drying process, and measurement reliability. Thus, the
surface of a solid object should be as large as possible. Since solid objects
release moisture through their outer surface, sample thickness is another
important factor.
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