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Elizabeth Henderson
Product Development Manager ITAC Ltd |
This month’s blog discusses an element used by Itac only as
a compound – iron. But as the mainstay of the construction industry and one of
the commonest elements of our planet, it plays a major role in our business. We
use coloured iron compounds in our products - iron’s oxides are familiar as
rust, and they are refined to produce stable pigments of either red or yellow
colour. They have excellent resistance to sunlight as well as good chemical
stability. With good hiding power and colour strength they make a valuable
contribution to the appearance of a painted item.
In addition to its
place in the red and yellow part of the spectrum, iron is the key component of
Prussian Blue pigment, which is iron(III) ferrocyanide. The yellow colour of
FeO arises from iron in oxidation state 2, the red in Fe2O3 from
iron in oxidation state 3. The characteristic blue of iron(III) ferrocyanide
arises from the presence of iron in both oxidation states in the compound. These three colours all from the same element
are demonstrated in the colours found in natural mineral Tiger’s Eye. This
material has a characteristic fibrous appearance associated with its source
crocidolite which has been replaced by silica, and the three naturally occurring
colours (yellow-brown, red and blue) arise because of contamination by iron in
various oxidation states.
Itac has recently bought Delvemade Ltd, and we now supply
paints for roofing, designed to prevent iron doing what it likes to do most of
all – oxidise to rust. ‘Delcote’ coatings are applied to corrugated iron which
has been factory finished in a coil-coating process but needs refreshing
because of weathering and exposure to pollutants. The paint has to bond
successfully to the original finish and extend the life expectancy of the
building as well as improving its appearance.
The
magnetic properties of iron are also exploited in specialised adhesives and
coatings. Magnetite (mixed oxidation-state iron oxide) is incorporated in
specialist inks (seen on the bottom of cheques) which can be read by magnetic
readers. High-spec adhesives have been devised incorporating very fine iron
dust, which heats up very quickly in a magnetic field and initiates the thermal
cure of the adhesive medium very quickly.
