IMPROVEMENTS IN PROTECTING SUBMERGED STRUCTURES OF IRON OR STEEL FROM CORROSION AND FOULING AND IN COMPOSITIONS THEREFOR"
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Farnham Maxwell Lyte at the Office
of the Commissioners of Patents on the 2nd October 1883.
"
FARNHAM MAXWELL LYTE of Cotford, Oakhill Road Putney in the County of
Surrey, IMPROVEMENTS IN PROTECTING SUBMERGED STRUCTURES OF IRON OR
STEEL FROM CORROSION AND FOULING AND IN COMPOSITIONS THEREFOR"
When Iron is immersed in water, particularly sea water, it is especially liable to
injury by:
1 The corrosion of the metal by oxidation.
2nd The fouling of its surface by the growth of weeds, barnacles, &c, and by dirt,
and the first cause of injury is easily obviated by protecting the surface of the iron
by paint; the second cause is however not so easily disposed of.
Several anti-fouling compositions are already known which are applicable to
wooden surfaces. When however they are applied to Iron, the electro-positive iron
reduces the more electro-negative metals they contain, and the paint detaches or
becomes destroyed and decomposed.
To obviate this, I propose to first protect iron and steel from corrosion by the
application thereto of an inert paint, and secondly to apply upon such anti-
corrosive paint, a paint having antifouling or poisonous qualities, the mode of
preparing and applying these paints being as follows:-A paint is made by mixing
drying oil, with or without turps, with oxide of zinc or bydrated oxide of zinc,
adding to this if necessary a certain percentage (say 10%) of peroxide of lead, or
the requisite quantity of red lead or some lead compound to promote drying. As
the lead is only added to promote drying, its addition or the proportion in which
it is added is not essential; suffice it to say that a paint is composed having for a
basis the oxide or hydrated oxide of zinc. With this compound which is inert to
Iron, the surface of the iron (as free as possible from previous corrosion) is to be
coated with one or more first coats. The iron being thus protected and isolated, a
coat of poisonous paint is applied upon this protective coating.
The following is the method employed for rendering this coat anti-fouling or
poisonous to weeds, barnacles, &c:-A paint is composed with a basis of oxide of
zinc, white lead, or any of the usual compounds, and to this is added a quantity

page_text: sufficient to be poisonous to these growths, of Scheele's or Schweinfurt green
(arsenite of copper, or the compound of the basic-acetate and arsenite of copper) or
one of the oxides of copper or the basic acetate of copper by itself or one of the
insoluble salts of copper, and if necessary the requisite quantity of peroxide of lead
or some lead compound to promote drying.
The poisonous coating may also be composed of arsenite of zinc. This may be
made by adding arsenite of soda produced by boiling arsenious acid in a solution of
sodium carbonate until it will dissolve no more, and then adding the same to a
solution of a zinc salt, say the chloride or the sulphate.
An anti-fouling paint coating may also be produced by painting the surface with
the arsenite of peroxide of iron, or the arsenite of lead. The arsenates of copper,
iron, zinc, and lead may also be used. Any ordinary antifouling paint may also
be used.
It will be observed that this Invention depends upon :-
1 The protection of the iron by means of a first coating of an inert paint
having for its basis oxide of zinc.
2nd Applying thereupon a paint containing arsenic or copper in one of their
forms as arsenious or arsenic acid chemically combined (not mixed) with certain
other metals or any antifouling paint in order to poison growth.
Besides the oxide of zinc proposed for the first layer or layers of paint, sulphate
of baryta (fixed white) or even iron oxide paint may be employed. Plain drying
oil may also be employed and the paint may be made up with varnish as well as
with drying oil.
Sulphide of zinc or the so called silicate paint may also be used, but the zinc
mixed with drying oil as recommended above appears to answer as well as any.