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this one, which, however, dates from more than half a
century ago. Stas ends his explanations by a phrase,
which may be regarded as the summary of his thesis, namely,
that it is to the absence of a proper amount of metallic
soap, dissolved in the oil and forming a metallic salt in
white zinc paint, that the latter does not possess the
elasticity, the impermeability, and the resistance, which
white lead paint undoubtedly possesses, which owes
precisely these qualities to the presence, in considerable
quantity, of lead salts, which are dissolved therein, and
which remain dissolved in the conditions under which paint
is applied', but, adds Stas, "in the interior of houses
and edifices, where the destructive atmospheric agents do
not act at all, or at least only act very feebly, white zinc
paint, like all paints made with linseed oil, and some solid
body, which does not of itself induce the destruction of
the dried oil, may be employed with the greatest advan-
tage ; and its role will always be so pretty, that one can
say that its manufacture at a moderate price and its


application as a paint forms one of the glorious conquests
of the century." Finally, showing how white zinc was
capable of improvement and having no doubt of the pro-
gress of industrial chemistry, or of human genius, Stas
wrote, "If we do not abuse the role which white lead
plays in painting, the oxide of lead which becomes soluble
passes to and remains in the condition of linoleate or
margarate of lead in the oil, before and after its drying ;
it ought to be possible to make by means of white zinc,
or any other inert matter, and linseed oil, in which there
has been directly dissolved a proper amount of these lead
soaps, or any other white metallic linoleate, possessing
the properties of linoleate of lead, a paint which stands
out of doors as well as white lead paint, although paint
of this nature must be affected by sulphuretted emanations ;
none the less, it is of great interest, that this experiment
be tried on the large scale."

This was to indicate, in very modest language, the
methods to be used to endow zinc oxide with the pro-
perties of durability which it did not possess. Stas, in
fact, demonstrated theoretically that in preparing oils,
saponified by lead salts, and utilised, either in the grind-
ing of the white zinc or in the composition of the liquid
paints, we ought to obtain zinc paint as supple, as im-
permeable, as resistant as may be desired, and yet no
manufacturer has dreamt of pursuing this path, all
mapped out for useful researches. It took nothing
less than the long and weary campaign against white
lead, of 1900 to 1909, to induce the manufacturers of
white zinc to make researches with a view of improving
this product ; and it is only in the later days of this


campaign, that some new if not fortunate attempts were

The Hydrated White Zinc now on the Market. Amongst
these different attempts, that of Georges Petit is to be
specially distinguished, because it attacks the sole question
to be solved. Modify white zinc in such a way that it
may possess, in itself, all the practical advantages and
properties which it is blamed for not having. The
problem has been enunciated ; it is wholly comprised in
the data and the theory of Stas ; and although Petit
declares this theory false, it is none the less on it and on
its data that he bases his system of manufacture of
hydrated white zinc, of which he is the inventor that
is to say, the saponification of the oil, or the formation
of metallic salts, dissolved therein. Petit would appear
to have tried to exceed by far the hopes of Stas, who
hardly saw the possibility of the saponification of the oil
and the presence of metallic salts in a paint, except in
utilising the combination which he had described, such
as the lead soaps ; whilst the inventor of hydrated white
zinc declares it possible to bring about and obtain this
combination by zinc soaps. For that purpose he utilises
the effects of water in hydrating white zinc when it is
being ground, as Launay, Druzon, & Co. had themselves
done fifty years ago as a matter of economy, whilst he
did it to obtain the saponification of the oil forming the
metallic salts of which Stas speaks, and to the absence
of which he attributes the want of elasticity and imper-
meability. He had, however, shown that these salts
might be obtained in very small quantity by increase of
temperature in the course of a laboratory experiment,


but they do not remain in solution in the mass after
cooling", and that they were thus non-existent or of no
effect, under the conditions in which paint is generally
used. Now with hydrated white zinc we have to deal,
according to Georges Petit, no longer with a simple
mixture of oil and oxide of zinc, but with a new com-
pound resulting, as in the case of white lead, from a
chemical combination, which itself results from the
generation and the presence, by the wet way, hydration
of a zinc soap, in the ground stiff paint ; this is, at least,
the way in which the phenomena can be explained that
is to say, the possibility of a combination between the oil
and the white zinc, a combination which the inventor
asserts exists actually, and which is created by his
method of hydration and grinding, applied to ordinary
commercial white zinc. Now it is necessary to know
whether the salts of zinc obtained by this method
remain dissolved in the oil, after as well as before the
drying of the paint, for if they do not remain in solution
in the liquid paint, or if they separate from the oil,
through drying, the necessary conditions for the chemical
combination are not fulfilled ; and in that case we would
still have to deal with a mixture of inert matter in the
oxidised oil, with oxide of zinc, in powder held in sus-
pension in an oily binder, the sole agent of durability
and resistance. It is for time and practical observation
to elucidate this capital point, the most important of all,
and if the assertions of the inventor of hydrated white
zinc are confirmed, and controlled by future facts, it can
be said, in the near future, that it is to the French
campaign against white lead, and which the Author


[Fleury] opposed, that we finally owe the discovery of
an ideal product, a real substitute for white lead in all
its forms, with the property of being harmless, from a
hygienic point of view, which was wanting in white lead,
justly accused of being a poison, which no painter has
disputed, because it was from all time an indisputable
truth. As far as the Author is concerned, he fervently
hopes that hydrated zinc oxide fulfils all its promises.
The reality of its discovery would then be a real humani-
tarian blessing, because it would permit of the abandon-
ment everywhere, without any regret, of the use of a
very noxious pigment, which was only employed so long,
through the want of a similar product having the same
combined practical and economical properties.

But has Georges Petit by his scientific treatment of
zinc oxide succeeded in filling the gap by supplying to
hydrated white zinc these two indispensable properties ?
Theoretically, yes, but from a practical point of view an
infallible decision cannot yet be given ; because, whatever
it may be during an average period, the beautiful ap-
pearance and condition of the practical trials made with
a paint product, it is necessary at the outset to multiply
these experiments, and then leave them plenty of time
to produce all their effects. Now the lapse of time
recognised as necessary to this manifestation comprises
a minimum period of five full and complete years, at the
expiry of which one can hope to be able to give a decision
in conformity with the truth. This delay is, here, still
more necessary, as it is a case in point of a pigment
which has to be used as the essential basis of paints and
priming coats in building construction. Therefore, do not


let us shout victory too soon, for, after five or six years'
practical experience with hydrated white zinc, it will be
necessary to know if the latter behaves not as well but
much better than non-hydrated white zinc. Such is the
material proof to furnish, the more so as it is asserted that
the white zincs (ordinary oxides) judicially used behave very
well for four years and even longer. Under such circum-
stances hydrated white zinc to be declared the best must,
above all, show itself superior to all others by its longer
life and its greater permanency.



THE poisonous properties of white lead occupied the
attention of investigators for a long time, but so long
as the use of paint in buildings was somewhat restricted,
few efforts were made to substitute any other basis colour
for white lead. It was only, in 1779, that Courtois, a
manufacturing chemist attached to the laboratory of the
Academy of Dijon, discovered not white zinc but the pro-
perty which it possessed of not blackening under the con-
ditions in which white lead blackened. A little later,
another celebrated chemist, Guyton De Morveau, who
collaborated with the illustrious Lavoisier in creating
chemical language, was the first to propose to replace
white lead by zinc oxide. In painting, he pointed out
that white zinc did not dry so well as white lead, and
observed, on this point, that, by adding to the white
zinc paint a small amount of sulphate of the same
metal, this drawback was partially remedied. At this
time, Courtois, seeing himself encouraged by such a
scientific authority, undertook the manufacture of white
zinc on the large scale ; then he established retail shops,

in Dijon, and in Paris itself. The first applications of



this paint were made in artistic painting- ; as regards
house-painting from the time of the trial made in the
beginning it was the object of severe criticism. It
was blamed for not covering as much as white lead
and for drying much less rapidly. These criticisms,
which are still formulated at the present day,
were nevertheless contested at this time, not by a
painter, but an artist painter, Montpetit, who tried to
refute the assertions of house-painters, whose trade
practice was, necessarily, quite different from artistic
practice. Montpetit sent a memoir, refuting the criticisms
of the painters, to the Royal Academy of Architecture of
Paris, which nominated a Commission. The latter made
a report, entirely favourable to the opinions expressed
by the author of the memoir, and, therefore, contrary to
the opinion of practical painters and to their criticisms.
This was the first conflict between the theoretical men
and the practical men, and it was destined not to be
the last. Following up this report of the Academy of
Architecture, the Ministry of Marine made experiments
on the large scale with white zinc paint, in the interior of
the vessel Languedoc ; and a Commission, nominated to
examine the paintwork, likewise pronounced in favour of
white zinc. On this advice, Marshal De Castries, then
Minister of Marine (1782), decided to adopt white zinc
for the interior painting of the Government Navy. This
first Commission of examination, and this first ministerial
decree in favour of white zinc were destined in the future
to have numerous repetitions. All these facts concern-
ing white zinc, from 1779 to 1782, experiments, reports,
and commissions were already public property in


France, when an Englishman, Atkinson, took out in
1786 a patent for the manufacture of white zinc, and its
use in painting- ! ! ! But Guyton de Morveau, roused
at such audacity, claimed for France the priority of
this discovery. He succeeded, as was only just. At the
same time he returned to the question, making person-
ally or in collaboration with Courtois, strenuous efforts
to launch the new product, to the popularisation of which
he devoted from 1786 to 1802. But, in spite of his
efforts, white zinc did not, however, enter into the
practice of painters. The question was buried, and was
not resurrected until 1808, in connection with a report
on the paint products, which one Mollerat presented to
the Institut National (Academy of Science) products
which, he declared, were manufactured by quite special
processes. It was the renowned chemists, Fourcroix,
Berthollet, and Vauquelin, who were entrusted with
the report on these products, amongst which white
zinc figures. These grand men of science prepared a
report of remarkable precision, and their decision, al-
though more than a century old, still retains its force to
a great extent. The defects with which white zinc is
blamed, they say, are so unimportant, compared with the
drawbacks of the present use of white lead, that one
cannot, reasonably, refuse to adopt it. The liquid paints
which it gives are more pure, more clean ; its lustre, if it
be less brilliant, does not tarnish. In equal quantity, it
covers a greater surface than white lead. It is true,
it does not spread so well, under the brush, but that is
remedied by charging the brush oftener, or giving- the
surface an extra coat, etc. etc.


In 1808, and up to about 1860, the drawbacks of white
lead were, in fact, considerable, but since then, and
more especially at the present time, white lead is enor-
mously altered, both in its manufacture and its use,
which has during- the polemics of the campaigns, under-
taken against this pigment, enabled the argument to be
reversed, so as to read, that the defects of white lead are
so unimportant, compared with the drawbacks of white
zinc, that one cannot rationally condemn the former to
bestow all preference on the latter.

However that may be, this report of Fourcroix,
Berthollet, and Vauquelin was, at the time, as Stas in
1855 says, in conformity with the facts enunciated by
Courtois and Guyton de Morveau. It concluded, in the
possibility of the substitution of white zinc for white
lead, and in the hygienic benefits which would result.
It enunciated, moreover, the principle agreed to by all
painters, namely, that white zinc paint requires a bigger
charge of paint and a greater number of coats. And
then, as Stas says, " On examining more closely the facts
which it contains, it was seen that the practical question
was far from being entirely solved. Two essential
elements were wanting to the solution of the problem
the cost price of white zinc, and the duration of the paint-
work executed with this white ; in one word, the
economic aspect of the question."

Now, at the present time, it is likewise the economic
side which remains, and will still remain for a long time,
the sole argument, the sole reason, of the hostility of
painters to the exclusive use of white zinc. It is the
economic side in manufacturing and practical matters


which is the capital point, the important and dominant
one. Roquette in 1842, and Mathieu in 1844, again
drew the attention of the industrial and scientific world
to zinc oxide and its use in painting, by making known
the industrial processes of the manufacture of this body,
but their efforts had no practical result. Towards this
period, Gaultier de Claubry speaks, in the Annales de
Hygiene Publique^ of the advantages of the substitution
of white zinc for white lead, and that is all, up to the
famous campaign of Leclaire. He, at least, as a practical
man, could put in practice the theory enunciated by
Courtois and Guyton de Morveau, sixty years previously.
The practical efficiency and the high authority of Leclaire,
together with his great probity, must necessarily have
imparted a gigantic impetus to the white zinc question,
which up to then had remained almost wholly within
the theoretical domain.

Let us hear what his contemporary, Stas, has once
more to say: "When Leclaire communicated the result
of his researches, he had already applied white zinc
to more than 2000 houses or public buildings. It is
certain that at this time an immense step was made. It
was not a question of 'experiments on a small scale. In
fact, the economical manufacture of white zinc had just
been solved by the same Leclaire, aided by Barruel, by
the discovery of a process of manufacture of white zinc,
which enabled it to be supplied in competition against
white lead ; a process which could be carried out without
any appreciable inconvenience to the workmen. Dis-
covering again a method by which white zinc paint
can be rendered drying, without first rendering the


linseed oil drying by means of a lead compound (litharge
boiled oil), finally, making known a whole series of
yellow and green colours, harmless and permanent, re-
placing all similar colours, with a lead, copper, and
arsenic basis, the economical reasons for stopping the
use of zinc oxide no longer existed, and the reproach
addressed to Guyton de Morveau, as to the defect of white
zinc paint not drying quickly enough, fell to the ground
after the discovery of the special drier (zumatic). Hence-
forth we possessed a perfectly harmless paint, of great
whiteness and economy, as regards its mineral con-
stituents. But it is to time to decide as to the compara-
tive permanency, under all conditions under which it must
be applied." At the time of Leclaire, the necessity for re-
placing white lead was doubted by no one. This pigment
then committed undoubted and too well known ravages,
and the substitution of another pigment, less actively in-
jurious, was an evident requirement for the whole world.

"It was, so far, true," says the same author, on
this point, that, when Leclaire announced, in 1848,
that a practice of four years had demonstrated to
him that zinc oxide, now termed white zinc, properly
prepared and used, could replace white lead for all
purposes, this discovery was received as a real blessing
by all connected with public hygiene. The facts which
Leclaire brought forward, in support of his assertions,
appeared, in fact, so convincing, that everybody believed
the question of the replacement of white lead was
definitely solved. For a time even the illusion was
such that every one seemed to agree in the futility of
continuing researches, undertaken in all directions, for


improvements in the manufacture of white lead, so as to
render it less unhealthy for the labourers.

"Some manufacturers went so far as to ask the legis-
lative interdiction of the manufacture of white lead ; and,
what was astonishing 1 , they succeeded in enlisting" in this
retrograde march the generality of white lead manufac-
turers through the medium of certain financial groups."

It will be seen from this remark, that the white lead
manufacturers of that time, like those of the present day,
cared more for their own particular interests than the
interests of their industry. They also must discount the
buying up of their factories under the form of a good
government indemnity (compensation). What characterises
Leclaire's campaign amongst all the others of the same
kind, and even the last French campaign, 1900-1909, was
the practical turn which it assumed from the beginning,
the official results obtained, and the honours decerned, to
this rich man, to this humanitarian, of the early days. In
1849 Leclaire obtained from the Societe d' Encouragement,
a gold medal as a proof of its gratitude for his works,
as a whole. In 1850 he obtained, from the Institut, the
grand prix Montyon, for his philanthropic acts.

The first decree interdicting white lead as the result
of this campaign was issued on the 24th August 1849, by
the Minister of Public Works. Afterwards, in February
1851, appeared the famous circular of De Presigny, the
Minister of the Interior, Agriculture, and Commerce.
This circular, so often quoted, so often appealed to, but
almost always given in an incomplete manner, was
printed with great wisdom, Appealing to the order of
the Minister of Public Works, in 1849, and basing him-


self on a new report of the same minister, and adopting
its conclusions, De Presigny says, especially, " In presence
of these conclusions, Monsieur Le Prefet, I believe it right
to ask you to take the necessary measures, so that white
zinc may be used, generally, in paintwork to be executed
in departmental buildings.

" An exclusive and absolute prescription would risk creat-
ing too sudden a disturbance in the important manufacture
of white lead, but it is essential, at least, that comparative
trials of both paints be made on a large scale, in such a
way that preference be irrevocably given to that one of
the two in which experiment shows superiority from the
double point of view, sanitary and economic."

That is not all the circular, but it is the essential part,
the only executive one treating the question legislatively.
All the part put in italics by the Author should still be
meditated on, for it is a real administrative pearl, a true
model of ministerial judgment.

After what has been already seen in this history, of
efforts made for seventy years, by grand men of science,
by great philanthropists, and by public authorities, in
favour of white zinc, it might be believed that white lead
was finally dethroned from its supremacy in paint-
work. However, it was nothing of the kind. Public
authorities brought the best of will to bear, but whatever
their intentions, they did not agree to go so far as to
suppress white lead by legislative enactment. They re-
coiled before the consequences. They were restrained by
certain considerations, contained in the reports them-
selves, from which they justified their decrees against
the pernicious white. It must be well recognised, in


fact, that in all the consultations demanded there was,
alongside praises of w r hite zinc, restrictions which had
to be taken into account, which could not be overlooked.

The report of 1786 to the Minister of Marine says
that the white zinc paint used on the Languedoc took
six days to dry, and that white lead only took four days.
Hence, less drying.

The report of Fourcroix, Berthollet, and Vauquelin, of
1808, stated, that white zinc spread less satisfactorily ;
that is to say, that it yields less than white lead, not
supplying so much under the brush, that an extra coat
must be given, therefore covering less, and thus justifying
the critical complaints of practical painters.

After Leclaire's campaign, however, and in spite of the
Presigny Circular, which in itself is very restrictive or
very prudent after Leclaire's campaign, we repeat, the
Government seems, at last, to have decided to solve the
problem more radically than by decrees or regulations.
In 1853 a Commission, consisting of members of the
Committee of Arts and Manufactures, and of the Com-
mittee of Public Health, were specially charged to
investigate whether there was occasion to prohibit, in
an absolute manner, not only the use for all paintwork,
but even the manufacture, of white lead. It has been
already seen that the generality of white lead manu-
facturers were enlisted into a retrograde step of this
nature, but that this retrograde step was rather the result
of certain financial combinations than the act of well-
formed opinion.

The Government might believe, with more conviction
than calculation, and in face of such a unanimous


manifestation, it was its duty to submit the question
of the total and radical suppression of white lead to
official scientific authorities, the more so as it was
solicited by those to whom it was their own vested
industry. Now, the Government Commission, although
declaring itself persuaded that the substitution of white
zinc for white lead was in course of being brought about,
naturally, that Commission, however, did not dare to
propose the radical interdiction of the latter, either in
its use or in its manufacture, and it came to the following
conclusions :

" i. There is no occasion to interdict the manufacture
of white lead, the improvements introduced into this

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Online LibraryPaul FleuryThe preparation and uses of white zinc paints → online text (page 11 of 20)