Year: 1898

page_text: I, THOMAS CRISP SANDERSON, of Brooklyn, Humber Road, Westcombe Park, in
the County of Surrey, Manufacturing Chemist, do hereby declare the nature of
this invention to be as follows:-
My invention consists of improvements in the manufacture of white lead, and
refers, especially to that portion of the process for preparing paint, which con-
sists, in mixing white lead with oil.
In this process the white lead is added in the form of dry powder, but it is
sometimes mixed with the oil whilst in a pulpy wet state. In this case the oil
and the white lead tend to form a compact mass, from which the water can be
drawn off, and the residue milled in the usual manner. The drawback of this,
however, consists in the fact that several per cent. of water usually remains inter-
mixed with the mass of white lead and oil, and is liable to cause the ground
material to harden in the packages, consequently, this process is in most cases
unsuitable.
By my improved process I remove this undesirable residue of water in the
following manner:-
I compound the wet and pulpy white lead with the oil in the usual manner,
and remove the separated water as far as practicable. I then treat the mass in
a centrifugal machine. The mixed white lead and oil being of considerable
greater gravity than the water which still remains inter-mixed therewith, is
thrown with greater force against the periphery of the revolving container, and
the water is thus pressed out of it, and accumulates on the inner surface of the
mass nearer the centre. When the separation is judged to be complete, the
machine is stopped and the water can be drawn off, leaving the mixture of white
lead and oil ready for the grinding.
In carrying this process into effect on a manufacturing scale, I prefer to make
it continuous, supplying the mixed white lead and oil continuously, and deliver-
ing it into the centre of the centrifugal machine near the bottom, and removing
the dried mass and the water separately from the upper edge.
In mixing wet white lead with oil, it is found that more oil is requisite than
when the white lead is mixed in the dry state, and the mixing requires consider-
able time for its effective carrying out. The time required can be considerably
shortened by the use of a larger excess of oil, but the finished product after
grinding is usually too soft to suit the requirements of the consumers.
Dated the 19th day of May 1898

page_text: Improvements in or relating to the Manufacture of White Lead Paint.
I, THOMAS CRISP SANDERSON, of Brooklyn, Humber Road, Westcombe Park, in
the County of Surrey, Manufacturing Chemist, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particu-
larly described and ascertained in and by the following statement:-
My present invention consists in certain improvements in the manufacture of
white lead, and refers especially to the preparation of paint therefrom by mixing
the said white lead with oil.
My process is especially designed to apply to the pulpy white lead produced
by precipitation of the same from a basic acetate solution, but it may also
obviously be applied to moist white lead produced by other processes than the
aforesaid.
In the ordinary process of mixing or grinding white lead with oil for the
production of paint, the white lead is usually added in the form of dry powder,
but it is sometimes mixed with the oil whilst in a pulpy wet state. In this case
the oil and the white lead tend to form a compact mass, from which the water
can be drawn off, and the residue milled in the usual manner. The drawback
of this, however, consists in the fact that several per cent. of water usually remain
intermixed with the mass of white lead and oil and is liable to diminish the
quality of the finished article, consequently, this process is in most cases un-
suitable.
By my improved process I remove this undesirable residue of water in the
following manner:-
1 compound the wet and pulpy white lead with the oil in the usual manner,
and remove the separated water as far as practicable. I then treat the mass in
a centrifugal machine. The mixed white lead and oil being of considerably
greater gravity than the water which still remains intermixed therewith, is
thrown with greater force against the periphery of the revolving container, and
the water is thus pressed out of it, and accumulates on the inner surface of the
mass nearer the centre. When the separation is judged to be complete, the
machine is stopped and the water can be drawn off, leaving the mixture of white
lead and oil ready for the grinding.
In carrying this process into effect on a manufacturing scale, I prefer to make
it continuous, supplying the mixed white lead and oil continuously, and deliver-
ing it into the centre of the centrifugal machine near the bottom, and removing
the dried mass and the water separately from the upper edge.
In mixing wet white lead with oil, it is found that more oil is requisite than
when the white lead is mixed in the dry state, and the mixing requires consider-
able time for its effective carrying out. The time required can be considerably
shortened by the use of a larger excess of oil, but the finished product after
grinding is usually too soft to suit the requirements of the consumers.
The excess of oil can be expelled from the mixture by mechanical pressure,
as for instance by means of a filter press or other well known device.
The advantage of my process as above described is not limited to its commercial
economy as compared with the ordinary process, involving the drying of the
white lead and the compounding with oil in the dry state. An essential point
in my process consists in the entire avoidance of the very harmful dust produced
by the handling of white lead in the dry state. This dust, in spite of every pre-
caution, is extremely liable to cause serious injury to the workmen engaged in
the manufacture, and it is therefore highly expedient on hygienic grounds to

page_text: avoid the necessity for drying the compound between its first precipitation, and
its final grinding with oil into paint.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:
1. The improvement in compounding white lead with oil, consisting in grind-
ing or commingling wet pulpy white lead with oil without special washing sub-
stantially as described.
2. In the process of compounding white lead with oil, substantially as set
forth in Claim 1, the separation of the adherent moisture expelled from the pores
of the white lead by the oil, together with any excess of oil present, by treating
the mass by centrifugal or other mechanical pressure, and withdrawing the
accumulated water, and excess of oil at intervals or continuously, substantially
as described.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.