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VARNISHES
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A KN ISM KS.
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Si-:C"T1()N I.
dkkinition. etc.. of vaijnishks-ilwv matkkials.
Definition.
The term " varnish '' is u.sed to desij^aiate any solution
which, when spread l)y means of a brush, in a thin layer
over the surface of an object, or applied thereto in a rational
manner by any other suitable means, dries (either by simple
evaporation of the solvent, as is the case with spirit varnishes,
or by the combined evaporation of the solvent, and the more
or less complete oxidation of the residue) to an adherent,
smooth, uniform, lustrous,elastic, shinin^j film, unaflected by
air or moisture.'
Utility.
Articles, whether consisting of wood, metal, glass, stone,
leather, [)aper, etc., are varnished because this impervious
film or coating preserves them from wear and tear, and the
oxidising action of air and moisture, and all those extraneous
influences included under the term " weather," noxious gases,
etc., whilst at the same time the uniform smoothness, trans-
parency and brilliancy of the film is pleasant to the eye and
the touch. Owing to the presence of antiseptic and toxic
substances in the resins, oils, etc., which enter into the com-
position of certain varnishes, these, in addition to preserving
the objects to which they are applied from ordinary wear
and tear, also protect them from the ravages of insects, c.tj.,
wooden structures from whiteants in tropical climates. "Dry
rot " may also be prevented in a similar way ; or varnishes
containing toxic principles, whether present naturally in the
'Wlien varnish is used as a vehicle for pignieuts a so-oalled "enamel"
is produced. Porcelain glazes arc true enamels. Aa varnisii enamels dry
with a gloss they save labour hy combining painting and varnishing inu.
one operation.
1
12 VARNISHES.
resins or solvent, or purposely added thereto, may prevent
undesirable lower forms of animal life from attaching them-
selves to the object to which they may have been applied,
e.g., antifouhng compositions, some of which, however, par-
take more of the nature of a paint than a varnish.
When
a coating of varnish has been given to anj^ article
it should dry rapidly to a uniform,durablefilm, possessingthe
properties just enumerated, neither crumbling nor cracking,
but persistently adhering to the object to which it has been
applied, and elastic enough to yield or stretch, with any bend-
ing action to which the article may be exposed, in its daily
use. In addition to a preservative action varnishes have also
a. decorative effect. This is due to the fact that the applica-
tion of a coat of varnish to anj^ porous surface, dressed and
smoothedin an appropriate manner, enhances its appearance
by imparting thereto the uniform polished glassy lustre just
referred to. Should the object to which it is applied consist
of previously dressed wood, by filling up the pores thereof
with a transparent media, it not only brings into bolder
relief the more prominent structural features of the wood, but
by a light and shade contrast (produced by the harder and
denser fibres as against the softer and less compact) brings
prominently into view all the characteristic modifications
and ramifications of the woody fibre of different timbers
known under the term " grain ". The whole structure of the
wood is, as it were, brought to the same level by actual con-
tactwith a glassysurface. By colouring the varnish a stained
glassy surface is produced, by which poorer quality timber
may he made to pass for better quality the same result may
;
also be arrived at by using naturally coloured resins, ex. 9
gamboge, dragon's blood, grass tree gum, etc.
Constituents.
The princi])al sul)stances which yield a coating fulfilhng
these requirements arc resins and drj'ing oils.
RAW MATKHIALS. 8
Si'iHiT Varnishes.
liL'sins Hit' sonietinies api)li('(l to the object to In* vfirnished
in the siiu])le state of solution in a volatile liquid such as
alcohol. Sui-h solutions arc termed .spiril varnishes. This
class of varnishes yields, however, on drying a brittle coat,
consisting practically of the unchanged original resin, pre-
senting all its merits and defects. Spirit varnishes are, there-
fore, liable to crack, and but little caleulated to withstand
wear and tear and the action of the weather. They cannot,
therefore, be used for outdoor decoration.
Oil Narxishks.
When
resins are dissolved by the aid of heat in a dry-
ing oil such as linseed oil • (so as to give the resulting coat
more elasticity), and the product thinned down with a vola-
tile solvent in which both oil and resin dissolve, such as
spirits of turpentine, oil varnishes are produced. Drying
oils play a double role : they not only act as solvents, but
impart elasticity and durability to the varnish. Oil varnishes
have consequently a much more varied and extended use.
not only for outdoor but also for indoor decoration.
Raw Materials.
As the quality of a varnish depends in great measure on
the materials from which it has been manufactured, it is
necessary, at the outset, to study the properties of these raw
materials, and their adaptability to serve the special purpose
for which the varnish is intended. Besides volatile oils and
other solvents, drying oils and gum resins, .several subsidiary
products are used in varnish-making, such as driers and
colouring principles.
Again, in the case of certain special varnishes, various
hydrocarbons are introduced, such as bitumens, aspliMltinn.
' Hesina omnis di^wolvituroUo.—J'tiiit/. xiv., 20.
— —
4 RESINS.
coal tar, bone, stearine and other pitches, inspissated juices,
such as india-rubber and gutta-percha. Collodion and
celluloid are also employed in varnish-making.
Kesins.
The resins, gum resins, balsams, etc., employed in varnish-
makintj are
:
Amber. Shellac.
Copal. Japan Lac or Uruschi.
Dammar. Chinese Lac.
Mastic. Dragon's Blood. /\Principally used as
Sandarach. Gamboge. colouring prin
{
Elemi. Accroides. ) ciples.
Benzoin. Asphaltum.
Turpentines. Pitches (coal tar, bone,stearine, etc.).
Rosin.
As resins play a part of supreme importance in varnish-
making, it behoves us to study them with care, and the par-
ticular trend of this study should bear upon such properties
as hardness, solubility in different solvents, etc.
—
Hardness. Resins are the ingredients which impart
hardness and brilliancy to varnishes. Knowing the hard-
ness of any resin, we can to a certain extent determine
beforehand the quahty of varnish it will produce. In
commerce, resins and gum resins are divided into classes,
according to their hardness viz., hard, semi-hard, medium,
and soft. The hard and semi-hard resins are furnished by
plants belonging to the Hymcncea (a family of plants apper-
taining to the sub-order of Ccvsalpinca) the principal of
,
which are the hard copals, or gum animes of Zanzibar,
Mozambique and Madagascar, and the semi-bard copals of
Sierra Leone, Benguela and Angola.
The medimn hard resins are produced by coniferous
trees, such are Manilla and Kauri copals.
AMin:H. T)
Fumlly, the soft resins aiv produced by plants of the
family of Ju(il(indacc(e, anu^nj^st which iue hcn/oin sandjinii h.
dra^'on's blood, and pjandjo^'c.
—
Solubility. As a general rule, the softer the resin the
more easily docs it dissolve, and, rice verso, the harder tlie
resin, the more insoluble it is.
The hard resins and semi-hard resins are but very slightly
soluble, but they are easily dissolved in spirits of turpentine,
linseed oil, and other solvents, by previously heating them in
such a manner as to cause them to lose 10 to 2.") per cent, or
more of their weight, according to the variety of resin dealt
with.
Besides its solubility, we have to note, in the case of each
resin, its origin, its composition, the principal commercial
varieties met with in the market, also the adulterations to
which each resin is subject, and the means whereby such
adulteration maj' be detected, as well as the conditions to be
observed, in the manufacture of good quality varnish from
any given resin.
1. .VMliKR. (Dcnsily, I'OH.)
(Synouyms: Lat. succiutiiit, Gr. clvctnm, Fr. succiu, (n-r. beruxtcin.)
—
History. Amberwas known manycenturies before Christ.
The English word "electricity" is derived from the ancient
Greek name for amber, viz., electron. Theophrastes (300 u.c.)
refers to its properties of electrical attraction. It is also re-
ferredtoindifferentconnectionsby Homer, I)ioscorides.Virgil,
Tacitus, Pliny, etc. The Latin term succiunm is derived from
succum, juice. Pliny states that it was supposed by their
ancestors to be the sap of the [)ine tvcv. Homer in his Chh/ssey
speaks of " a gold necklace ornamented with ambi-r bi-ads ".
Although amber is classed by mineralogists as a mineral, and
•renerallv. but erroneouslv. included bv them in the class of
6 RESINS.
bitumens, it is, in reality, a widely-distributed but, except in
—
one or two localities, a far from abundant fossil resin the
product principally of a prehistoric conifer, Finns succinifer,
which flourished many thousand years ago upon the green-
sand beds of the cretaceous formation. The vast forest upon
which these pines grew is supposed to have stretched from
Holland, through Germany, Siberia, Kamtchatka to North
America.
The cones of this tree are often found associated with
the resin, so as to leave no doubt as to its origin but,
;
according to Goppert, it is not the product of any one
single species, nor necessarily derived from a coniferous
tree. According to some authors, it may, in some cases,
be derived from the Hyniencea, a species of tree belonging to
the CoesalpinecB.
—
Localities. Amber is met with in thin plates and nodules
disseminated in the sands, clays and lignites of the green-
sand formation (lower tertiary) along the German shores
of the Baltic. It is sometimes found in thin plates
between the layers of lignites, but nearer the bark than
the centre of the trunk, as in the case of resin-bearing
trees of the present day. The district known as Samland,
in Eastern Germany, is the chief amber-mining centre.
It is from this district that the markets of the world are
supplied. Beyond Germany the yield of amber is com-
paratively trifling and the working unprofitable. On the
shores of Britain, especially on the Essex, Sussex, Nor-
folk^ and Suffolk coasts, after severe storms, such as the
autumnal and vernal equinoctial gales, as well as on the
coasts of Denmark and Scandinavia, it is often thrown up
on the beach. But in these cases there is every reason to
believe it has been washed away and drifted from the Baltic
' Specimens from Cromermay be seen in tlic Jermyn Street Geological
Museum, London.
AMJ;j;i{. (
l)e(ls. This is llu' iiioic cit'dible wlun wc riuiciiihfr tliiit ilu-
specific «,'ravity ol aiiihor is IIJS, aiitl that of sea water lO-JT,
and that the force of the waves will, at such a time of wind
and weather, easily overcome the small difference in i^'ravity
and cause the andier to drift with the current.
—
A sort of hyhrid between amher and copal copalint- t»r
—
High^ate resin is mentioned as found in the Lcjndon clay
at Highgatehill and Kensington (London), hut not in suf-
ficient quantity to he of any use ; moreover, it is as friable
as common rosin, and its connection with ami)er is very
problematical. Anii)i'r also occurs in the Paris Basin,
associated with the bituminous deposits of the Paris clay,
and in the departments of Aisne, Loire, Gard and Bas Khin,
and near Bale, in Switzerland. On the Sicilian coast green-
ish or bluish-violet specimens are found.' It is also found on
the Italian shores of the Adriatic. Near Prague, the capital
of Bohemia, in sinking a well an extensive deposit of amber
was come upon, some of the pieces weighing 2 to '4 lbs.
Beds of brown amber occur in Koumania, in the mountains
of Sibicio, Valley of Burgo, which, it is said, with capital,
skill and energy, might be worked profitably. Although
brown is the most prevalent colour, the tint passes through
orange, yellow, red, blue, green and even black, often with
veins of variegated hues and tints.
In North America amber is found at Gay Head, near
Trenton, and Vincent Tow'n, Camden, New Jersey, the
specific gravity of tlu' latter being said to be less than thai
of water ; it also occurs at Capesable, Maryland. All the
United States' specimens are found in the red clay, subjacent
to the greensand or in the greensand itself.
—
Mininij and Drcdiiinij. Amber is mined in a greyish
black, peaty earth, in the Hakong ^'aIl^•y, S.W. of the
Mien Khorm Plains in British Buruiah, at an altitude of
' Fluorescentand otherspecimens from Catania, Sicily, are shown iu the
Jcrmyu Street Geological ^luseum, London.
8 • RESINS.
1050 feet. It is mined by sinking pits to a maximum depth
of 40 feet.
But the most extensive and productive amber-bearing
deposits in the world are found in the district of Samland,
Eastern Prussia. The amber is mined for systematically,
and the working of the mines is a monopoly of the Ger-
man Government. It is found at a depth of 108 feet be-
low the surface and 46 feet below sea level, in the blue
earth, a friable bluish freestone, constituting the lowest
stratum of the chalk formation in that region. It varies
in thickness from 10 to 30 feet, but only the lowest, 6 to
12 feet, are worked, and as the working is below sea level
great care has to be exercised to prevent the shafts and
tunnels being swamped by an inflow of sea water and
sand. The earth sent up to the surface for examina-
tion was formerly washed through a wide-meshed screen
or sieve into a long inclined trough, at distances of 6 feet
apart the valuable pieces of amber were collected by
;
means of nets. The rubbish or tailings are run into the sea,
through a sieve with meshes of about one-third of an inch.
Latterly, however, the troughs and nets have been replaced
by sifting machines or jiggers. These jiggers are fitted with
sieves with a mesh of one-eighth of an inch, and can pass
from 15 to 20 tons of earth through them hourly.
The amount of earth dealt with monthly in these mines
is about 7500 tons to 12,500 tons, giving 8 to (5 tons of
" large" and a ton to three-quarters of " smalls," the cost of
production varying from 4s. 6d. to 7s. a lb. 20 cubic feet of
;
earth yields about 2i lbs. of amber of a mean value at the
mines of Is. 8d. for small and 7s. (h1. for large. The exact
extent and geological distribution of these amber deposits of
Eastern Prussia have not been definitely ascertained, as
during hurricanes very appreciable quantities of resin are
found amongst the debris washed from the sand hills that
exist along the coast of a lower geological horizon than the
—
AMUKK. .'
iiiiiirs. This varit'ly is kiiDwn as ///r.sc/( jiniln-i \^ii(iiii num-
timc), that from llit' mines heint; termed crd amber (succiu
terrestre).
Fliescu amber is softer than crd amber, has a smooth,
histrous, nniiulcd surface, whilst that from the mines, erd
aml)t'r, is an^ailar, rugose, and covered by a rather hard crust.
Marine amber is got bj' steam dredging at Schwarzort on
the Kurischer Haft", close to Memel. The yield by dredging
is close upon 100,000 lbs. annually, and this large yield has
verj' materially reduced the price. It occurs in nodules,
associated with lignite in the sand at a deptli of abcnit 10
feet. The sand, as it is dredged, is sent ashore and levi-
gated in the same way as mine amber. In all. Eastern
Prussia exports about 150 tons of amber annually. In
Western Germany amber occurs under circumstances similar
to those of Eastern Germany, viz., in the sea and mines, but
on land the mines are not at all profitable.
Insects of difterent genera living at the present day, but
all the species of which are extinct, are often found em-
bedded or entombed in amber, having found a living grave
in the original oleo-resin as it flowed from this almost
primeval pine, and amongst them several genera of spiders.
Some genera of the various insects found in amber still live
in America and Australia, but the species may be said to be
extinct, but a single living insect, found in America, has
been observed in amber, viz., Lcpisma saccliarininn.^
—
Varieties. According to M. Lebert the follnwing an- tlu'
different kinds of amber in the market :
(1) The coloured Amber of Kinnsl, pale yellow and shinin;^,
or greenish and dull.
(2) Bnstert Amher, a deeper, opaque yellow, citron to dark
vellow.
' Specimeus of amber, enclosing remains chiefly of .Vc«n>/>/<T<i and
Diptera, fromthePnissiau shores of tli" P.nltii- nn- exliil.iicd in tin- .Tinnvn
Street Geological Museum, London.
