Improved Method of and Means for the Application of Anti-fouling Coating for the Wooden Surfaces of Submerged 'Structures.
Year: 1899

page_text: Date of Application, 7th July, 1899-Accepted, 23rd Sept., 1899
Improved Method of and Means for the Application of Anti-fouling
Coating for the Wooden Surfaces of Submerged 'Structures.
A communication from abroad by GEORGE DENSMORE COLEMAN, of Boston, State
of Massachusetts, United States of America, Engineer.
I, REGINALD WILLIAM JAMES, of the Firm of Fell and James, of 1, Queen
Victoria Street, in the City of London, Chartered Patent Agent, do hereby declare
the nature of this invention, and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:-
The object of my invention is to produce an efficient anti-fouling coating for
wood and especially an anti-fouling coating for the wooden bottoms of sea going
vessels and for the submerged portions of docks and the like which are in contact
with the sea water, and which, in the absence of some anti-fouling coating, are
rapidly covered with marine growths, especially in the tropical seas, which in the
case of vessels materially diminishes their speed.
In the drawings accompanying this specification illustrating the preferred
form of my invention and in which like reference letters refer to like parts
throughout.
Figure 1 is a face view on a very much enlarged scale of a portion of a piece
of wood provided with indentations.
Figure 2 represents a cross-section on the same scale of a portion of a piece of
wood with my anti-fouling coating applied thereto.
Horetofore it has been customary to coat the bottoms of ships with sheet copper
which, being exposed to the action of the sea water is oxidized on its outer
surface and the oxides thus formed change to various other salts of copper which
being highly poisonous in their nature prevent the accumulation of marine
growths thereon. My invention contemplates a substitute for such copper surface
which shall be easily applied, efficiently held and at the same time made very
much more cheaper than the sheet copper_coating.
In carrying my invention into practice I apply to the surface of the wood com-
minuted copper which is embedded therein. The portions of the particles of
comminuted copper which remain exposed upon the surface of the wood become
oxidized by contact with the sea water and the oxides thus formed gradually
change into other salts of copper which efficiently prevent the accumulation of
marine growths upon the surface of the wood. While I have referred to com-
minuted copper as the material to be applied to and embedded in the surface of
the wood, I do not desire to limit myself specifically to that metal as it will be
readily understood that any alloy of copper or other metal which upon exposure
to the action of sea water becomes rapidly coated with salts poisonous to marine
growths is within the purview of my invention. So when I use the term copper
I would have it understood that I may use that metal or its alloys or any other
metal or alloy which decomposes in like manner.
The comminuted copper may be applied to, the surface of the wood by being
laid thereon and driven by suitable tools into the same. I prefer however to

page_text: apply the comminuted copper to the surface of the wood after the same shall have
been subjected to the action of tools which shall cut numerous indentations
through the outer surface of the wood. Into these indentations I then drive the
comminuted copper. As is well known when dry wood is indented and' after-
wards moistened a swelling of the fibre of the wood tends to obliterate the indeu-
tations by bringing the fibre to the surface again, so if the copper were merely
driven into the smooth surface of the wood it might be that when the wood was
moistened by immersion in water that the particles of copper might be thrown
off. In order to prevent this shedding of the particles of copper I consider that
it is preferable previously to cut indentations in the wood. By this means the
continuity of the surface fibre of the wood is destroyed and when the copper is
embedded in the previously formed indentations it will be securely held by the
wood when the wood shall be moistened, because the swelling of the fibre by
reason of the moisture will not act to shed or throw off the particles of copper,
but the fibre will swell around them, and hold them securely in the surface of the
wood.
It is not necessary that the particles of copper should completely cover the
entire surface of the wood for the reason that as the copper decomposes under the
action of the sea water the salts thereby formed will spread around each particle
of copper upon the contiguous surfaces of the wood covering the whole surface
with a coating of poisonous salts to which marine growths will not attach them-
selves.
Although it is quite practical and within the purview of my invention to apply
the comminuted copper directly to the indented surface of the wood and to ham-
mer the same thereinto, I have found it convenient and preferable to apply the
comminuted copper to the surface of the wood in a paste soluble in water. By
this means I am enabled to apply to the surface of the wood a coating of com-
minuted copper in position to be driven into the surface of the wood by a hammer
or any other suitable tool. After the hammering process is completed the soluble
paste may be washed off and thus affords a ready means of examining the sur-
face and determining as the work progresses the closeness of the particles of copper
to each other.
In case the comminuted copper is applied directly to the wood without the use
of a paste, or after the paste has been washed off and the surface of the wood is
exposed, it will be found to be provided with a coating of many small pieces of
copper embedded in the wood. This coating is an efficient one for the prevention
of accumulation of marine growths, but I prefer at this stage to coat the whole
with a paint composed of the poisonous salts of copper which paint efficiently
fills the interstices between the small particles of copper and at the same time
promotes the decomposition of these particles when subjected to the action of
sea water.
This paint of the poisonous salts of copper may be any of the well known anti-
fouling paints or a paint entirely of such poisonous salts of copper or any material
which will become poisonous on exposure. to sea water in the presence of copper,
and any desired volatile binder which will serve to tie the substance together
until it shall become hard and dry. It may be applied with a brush or with a
trowel depending upon its consistency and the amount desired to be applied and
the surface may be smoothed in any suitable or desired manner.
When wood coated in the above manner is subjected to the action of sea water
the anti-fouling substance which fills the interstices between the embedded par-
ticles of comminuted copper will of. course gradually be abraded and' washed off
by the action of the water, but the particles of copper being at the same time
subjected to the action of the sea water will be decomposed and serve to renew the
anti-fouling substance lost from between the particles of comminuted copper.
In Fig. 1 of the drawing I have illustrated a portion of the surface of the wood
provided with indentations A to receive the particles of comminuted copper, and
in Fig. 2 I have shown a cross-section of a portion of a piece of wood B through

page_text: the coating, wherein C indicates the particles of comminuted copper and Dindi-
cates the surface coating of anti-fouling substance in the interstices between the
particles of comminuted copper. This figure clearly shows, on a much enlarged
scale, the embedding of the particles of copper in the surface of the wood.
I am aware that it is old to apply a coating to the bottom of ships which con-
sists of a paint such as red lead having suspended therein particles of comminuted
copper, but it will be observed that such coating is radically different from the
coating which I apply, and moreover it is liable to be chipped or flaked off from
the bottom of the vessel by accidental contact with flotsam, while my coating,
being attached at every point to the surface of the wood is not liable to scale or
chip off but in case of injury thereto the injury is confined to the precise spot
struck, besides which the copper being embedded in the wood cannot he easily
removed therefrom by such chance blows, and even if the surface were severely
indented would still present anti-fouling material to the water and thereby pre-
vent the accumulation of marine growths. In other words the comminuted copper
applied according to my invention makes a very much more durable coating by
reason of its being embedded in the surface of the wood and not merely attached
thereto by force of cohesion, and having the further advantage of renewing itself
by decomposition of the metallic copper.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I.declare that what I claim is :-
1. An anti-fouling coating for wood which consists of comminuted copper or
other suitable substances embedded in the surface of the wood, substantially as
described.
2. An anti-fouling coating for wood which consists of comminuted copper or
other suitable substance embedded in the surface of the wood and a surface coat-
ing of anti-fouling substance in the interstices between the embedded particles
of comminuted substance, substantially as described.
Dated this 7th day of July 1899.
FELL & JAMES,
Agents for the Applicant.

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