Waterproofing ingredients for
oilcloth.
2.2.1 Drying Oil Recipes
A source from 1758 describes the
preparation of drying oil (mainly intended for “coarser work”) as involving
boiling or simmering the oil in conjunction with a variety of driers used at
once, including litharge, white lead, red lead, lead acetate, and sulfate of
zinc (Dossie
1758, 148–49). Reports on the color of these early drying oils indicate
that they could be very dark: “a good drying oil is not to be had of them [the
colormen], what they furnish us with being so highly colored as to be improper
for the purposes of fine painting, and only can be admitted in the darkest
shades or back grounds” (Williams
1787, 25). By contrast, recipes provided in the artists' oil painting
instruction books were largely directed toward the preparation of a drying oil
that would be as colorless as possible; these tended to include only one type
of drier.
One of the preferred methods was to
use metallic lead, either by agitating the oil with lead shot or by “grinding”
the oil with a leaden pestle in a lead-lined mortar. Prolonged storage in a
leaden vessel was also recommended. Litharge (and very occasionally white lead)
was sometimes substituted for metallic lead and used in a similar manner. For
example, Rembrandt Peale's method was to add 2 tablespoons of litharge to and
8-ounce phial which was then filled with linseed oil. It was to be kept exposed
to the sun or near a fire for a few days and shanken frequently (Sully
1873, 33).
Litharge was available in two
varieties: silver and gold. Silver, or yellow litharge, was heated higher and
was reported to be a harder material than the gold, or red litharge. Field
(1841, 108) recommended the silver over the gold because it was more highly
oxidized and would therefore make a more effective drier. Sources warned that
litharge was often contaminated with iron or copper oxides and noted that it
contained significant amounts of silica as an impurity. Although
The earliest recipes for drying oils
in the sources consulted contained the highest proportion of driers to oil. In
later publications, the ratio of 1 part drier to 8 parts oil or 1 part drier to
16 parts oil became more common. The preparation of drying oil was dangerous
because of the risk of fire and required skilled workmen to achieve a
consistently high-quality product. Judging from orders for both oil and driers,
it appears that Roberson's prepared its own drying oil between 1830 to 1853.
Sometime after, the firm consistently purchased drying oils ready-made.
OIL
PAINTS
Linseed oil, obtained by crushing flax, was the most important oil
for use in oil paints. Its rather yellow colour was a drawback, and for more
delicate shades other more expensive oils, like walnut or poppy seed, were
sometimes used. These are all 'drying oils' - they absorb oxygen from the
atmosphere to form a hard flexible film. This reaction could be accelerated by
the addition of driers, notably litharge or lead monoxide, to the linseed oil.
Grinding white lead (basic lead carbonate) with linseed oil produced a mixture
called 'lead soap', which was an outstandingly flexible and adhesive coating.
It also had excellent opacity, or covering power, whilst many other white
pigments, such as chalk, became almost transparent in oil. White lead also
helped the linseed oil to dry, unlike some other pigments, such as lampblack,
which slowed the drying process.
White lead had been known since antiquity to be the best white
pigment available for use with drying oils. It was made by suspending sheets of
lead metal over vinegar in covered pots. These were then laid in a dung heap to
keep warm for several weeks to allow the fumes from the vinegar to react with
the lead. After removal, the white lead powder (lead carbonate) which formed on
the surface of the sheets was ground to a fine powder. This was called the
Dutch or stack process and was used until the late 19th century when the more
efficient chamber process was developed.
The white lead was originally ground with the linseed oil by hand
using a Muller and Slab, then later by machines such as cone mills or edge
runners driven by horse or steam power. Paints typically contained over 80 per
cent white lead with the balance made up of the linseed oil binder and
turpentine as the solvent. The balance between these two dictated the
properties of the paint. More oil than turpentine gave a well-bound but glossy
paint that was more resistant to the weather, and was suitable for outside and
inside use; more turpentine than oil gave a matt finish that was suitable for
indoor use only.
To make a Composition
for rendering Canvas, Linen, and Cloth durable, Pliable, and Water-proof. To
make it Black. First, the canvas, linen, or cloth is to be washed
with hot or cold water, the former preferable, so as to discharge the
stiffening which all new canvas, linen, or cloth contains; when the stiffening
is perfectly discharged, hang the canvas, linen, or cloth up to dry; when
perfectly so, it must be constantly rubbed by the hand until it becomes supple;
it must then be stretched in a hollow frame very tight, and the following
ingredients are to be laid on with a brush for the first coat, viz., 8 qts. of
boiled linseed oil, 1/2 oz. of burnt umber, 1/4 oz. of sugar of lead,
1/4 oz. of white vitriol,
1/4 oz. of white lead.
The above ingredients, except the white lead, must be ground fine with a small quantity of the above-mentioned oil, on a stone or muller; then mix all the ingredients up with the oil, and add 3 oz. of lampblack, which must be put over a slow fire in an iron broad vessel, and kept stirred until the grease disappears. In consequences of the canvas being washed and then rubbed, it will appear rough and nappy; the following method must be taken with the second coat, viz., the same ingredients as before, except the white lead; this coat with set in a few hours, according to the weather; when set take a dry paint-brush and work it very hard with the grain of the canvas; this will cause the nap to lie smooth.
The third and last coat makes a complete jet-black, which continues its color: Take 3 galls. of boiled linseed oil, and ounce of burnt umber, 1/2 oz. of sugar of lead, 1/4 oz. of white vitriol, 1/2 oz. of Prussian blue, and 1/4 oz. of verdigris; this must be all ground very fine in a small quantity of the above oil, then add 4 oz. of lampblack, put through the same process of fire as the first coat. The above are to be laid on and used at discretion, in a similar way to paint.
The above ingredients, except the white lead, must be ground fine with a small quantity of the above-mentioned oil, on a stone or muller; then mix all the ingredients up with the oil, and add 3 oz. of lampblack, which must be put over a slow fire in an iron broad vessel, and kept stirred until the grease disappears. In consequences of the canvas being washed and then rubbed, it will appear rough and nappy; the following method must be taken with the second coat, viz., the same ingredients as before, except the white lead; this coat with set in a few hours, according to the weather; when set take a dry paint-brush and work it very hard with the grain of the canvas; this will cause the nap to lie smooth.
The third and last coat makes a complete jet-black, which continues its color: Take 3 galls. of boiled linseed oil, and ounce of burnt umber, 1/2 oz. of sugar of lead, 1/4 oz. of white vitriol, 1/2 oz. of Prussian blue, and 1/4 oz. of verdigris; this must be all ground very fine in a small quantity of the above oil, then add 4 oz. of lampblack, put through the same process of fire as the first coat. The above are to be laid on and used at discretion, in a similar way to paint.
CYCLOPEDIA OF PAINTING
To
Make Gold Size. Take Gum Animi, Asphaltum, of each 1 ounce, minium
litharge of gold and umber, of each % ounce, reduce all into a veryfine powder,
and add to them, of linseed oil 4 ounces, of drying oil 8 ounces, digest over a
gentle fire that does not flame, so that it may only simmer and bubble up, but
not boil, for fear it should run over and set the house on fire.
Keep
constantly stirring with a stick till all the ingredients are dissolved and
incorporated, and do not leave off stirring it till it becomes thick and ropy,
and is boiled enough, let it stand till it is almost cold, and then strain it
through a coarse linen cloth, and keep it for use. To prepare for use, mix with
oil of turpentine during heating, and strain again, add vermilion, and thin as
required with turpentine. http://www.forgottenbooks.com/readbook_text/Cyclopedia_of_Painting_1000230154/405
Litharge is pure lead and when boiled with
linseed or Walnut oil creates what is called black oil. Carbonate of lead
contains moisture which is forced out by the heat. The lead fumes are poisonous
and the oil becomes poisonous.
Lead is rusted and becomes white ( flake
white). When burned again it becomes red oxide (used in painting barns). When
fired again it has the look of a light gray, thus Litharge of silver, when
fired again it becomes a soft yellow in colour,(Litharge of gold). When
Litharge of gold is mixed with one of the above oils and heated between 180 and
200 degrees centigrade the oil begins to smoke and turn brownish. The litharge
at 150 degrees begins to turn into scrap and sticks to the spatula. At
210 degrees the deposits soften and mixes with the oil. At 250 the lead is
permanently suspended in the oil and the colour is of clear brown coffee. It is
the black oil developed during the 1400 century. I can't caution you enough
about the danger of lead poisoning.
"The cloth was water-proofed by coating it with a boiled linseed and
"litharge of gold" After several coats of the oil preparation
were dry, the cloth was well sealed and remained flexible." 1758.
Oiled Umbrellas
Historically, the Chiang Mai umbrella cluster's central product
is the "oiled umbrella". Oiled umbrellas are made with a carefully
carved bamboo frame, then covered with fine cotton, to which different layers
of waterproofing are applied. While the natural waterproofing method is
regarded as somewhat of a local trade secret, it traditionally includes teak
oil and colour pigment. In the modern, more competitive marketplace, natural
materials may be combined with more easily available synthetic oils and colours.
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