Paints: Distempers - Lime Based Paints
Distempers
Distempers are those paints obtained by mixing water and glue.
More in general they are those paints in which charges and pigments
are kept together by a glue or a binder so to create a homogeneous
amaigame.
The name "distemper" comes from "stemperare",
ie: make a paste from a powder by blending with a liquid. In
the ancient times distemper was used also in reference to blends
with paints and oils. Afterwards, it has been referred only
to identifying pigments kept together by animal glues, vegetable
glues, egg, milk and so on. In the years distempers composition
evolved and changed so much to be sometimes confused, in its
results, with frescoes or oil paints.
From the explanation above, it is possible to summarize that
distemper can be defined as a kind of paint containing pigments,
bound by different gluing substances, to be applied pigmented
on a dry base.
Distemper is an evolution:
|
Pigments and Fillers
|
Binders
|
Ground marble dust (calcium carbonate)
Earth Pigments |
Egg yold, egg white, bones glue, rabbit glue,
fish glue, milk, milk coagulates, (casein). Four glue, rice
glue, |
Ground marble dust (calcium carbonate)
Earth Pigments |
Casein blended in lime-milk, cooked and raw
linen-seed oil. |
|
Meudon white,
Earth pigments, iron oxides
|
Cellulose ethers |
Meudon white, calcium carbonate
iron oxides, organic colorants
titanium dioxide |
Cellulose ethers
Polyvinylic resins |
Calcium Carbonate
iron oxides, organic colorants
titanium dioxide |
Cellulose ethers
Acrylic resings, Ethylene resins, Vynilversathate resins,
styrol-acrylic resings
|
In a nutshell, distemper is the mother of today's synthetic
latexes, which range from present distempers to "breathable"
latexes, from water-repellents to washable paints, from quarts-based
paints to syloxanics.
Lime-Based Paints
Whereas distempers in ancient times were used mainly to obtain
decorations, lime-based paints were used most-of-all to paint
big surfaces and facades.
After having known centures of heavy-use, in the second half
of the 19th century, lime-based paints lost popularity. Only
in the last 10 years lime-based paints became popular again,
most of the time somewhat modified to make it more suitable
to present times.
Raw materials suitable to lime-based paints are lime-grasselio
and "fiore" hydrated lime. Both are aerial limes (ie:
they harden slowly once in contact with air). Both are derived
from the same material (cooked lime stones) whether dry-ground
or made wet and left to dry.
|
Pigments, fillers, mineral binders
|
Organic binders
|
Lime grassello or hydrated lime
Meudon white
Earth Pigments |
Bones glue, fish glue, leather glue, flour
glue, rice glue, potato flour glue, milk casein, egg yolk,
egg white, ficus milk, nut oil, olive oil, raw and cooked
linen oil. |
Lime grassello or hydrated Lime
Calcium carbonate
Earth Pigments
Iron Oxides
Titanium Oxide |
Methyl cellulose
Acrylic resings
Linen oil
Pine oil
|
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Stuccos: Lime-Based - Gypsum Based
Lime-Based Stuccos
In general, lime-based stuccos are meant those finishing plasters
composed mainly of lime grassello or hydrated lime, blended
with marble powder (calcium carbonates) and organic substances.
According to the grain size of the filler (marble powder) they
would accomplish different effects:
| grassello lime-plaster |
shiny finish |
| marmorino lime-plaster |
satinated finish |
| travertine lime-plaster |
matt with scars of variable depth |
Lime-based plasters and their evolution:
|
Pigments, fillers, mineral binders
|
Organic binders
|
Lime grassello or hydrated lime
Meudon white
Earth Pigments
Lime grassello or hydrated lime
Inorganic pigments, earth pigments |
Fish glue, rabbit glue, casein, virgin wax,
soap, egg, olive oil, linen oil
Oil
Methyl cellulose, acrylic resin
|
Gypsum-Based Stuccos/Putties
Gypsum-based putties (or synthetics) were made of water, gypsum
and a solution of glues. They were used for interiors only for
decorative levellings or base-reliefs. They had the same durability
and consistency of lime-based stuccos with a fast hardening
process and no causticity at all. On the other hand, they had
a very small workability time-frame, being gypsum a hydraulic
material, it would harden in just a few tens of minutes. In
time, with the development of polyvinylic resings, gypsum for
decorative decorations was substituted by calcium carbonate,
which allows a workability similar to lime.
Gypsum-based stuccos and their evolution:
|
Fillers and pigments
|
Binders
|
Gypsum
Earth Pigments |
Fish glue, rabbit glue, flour glue |
Gypsum, hydrated lime
Earth pigments |
Fish glue, rabbit glue, casein |
Gypsum, calcium carbonate
Inorganic and organic pigments |
Methyl cellulose |
Calcium carbonate
Inorganic and organic pigments |
Methyl cellulose
acrylic resin |
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Plasters
Lime-Based Plasters
Since forever, plasters conjugated their aesthetic function
with the protection of the building.
The first examples of plasters can be identified with blends
of mud and clay, frequently modified with vegetale materials
like leaves, straw or animal dung.
By the times of the Greeks and the Romans, plaster was composed
of a number between 4 and 7 different layers. Today the usual
habit is 3 layers, on top of which decoration is created.
The first layer starting from the bricks is composed of a blend
of cement, hydraulic lime and coarse sand (approximately 2 to
8mm).
The second layer is composed of middle-size sand (0.6 to 2mm)
blended with hydraulic lime and hydrated lime.
Plasters and their evolution:
The composition of plasters remained practically unchanged
from the Greeks. The only variations have taken place in the
number of coats and in the finishing of the plaster. A plaster
application at the Romans' time for a patrician house was composed
of 7 layers:
| Rinzaffo |
Pozzolana, lime and coarse sand |
| Arriccio |
Possolana, lime and mid-size sand |
| Velo |
Lime and fine sand |
| Velo |
Lime and fine sand |
| Stucco |
Lime and marble dust |
| Stucco |
Lime and marble dust |
| Stucco |
Lime and marble dust |
Cement-Based Plasters
Cement-based plasters are very similar to lime-based plasters
as far as granulometry is concerned. Different from lime-plasters,
they do greatly reduce their permeability to water and become
very hard even in the presence of high humidity.
They are most suitable for structures in direct contact with
the weather where high surface durability is required.
They are absolutely unsuitable to support lime-based cycles.
Synthetic Plasters
They can have the same granulometry of the inerts, quite like
the lime or cement-based ones. Nevertheless, their binder is a
resin instead of a mineral. Such fact implies an overall durability
higher than lime or cement-based plasters. On the other hand,
such substrate prevents breathability.
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Colourants
The first colorants used in paints were earth pigments; they
are available in nature and change colour according to the place
they come from and the kind of sediment. The best known earth
pigments, presently used in restoration jobs are the following:
| Vine Black |
Obtained by the cooking of grapevine
wood |
| Manganese Black |
Composed of Managanese dioxide |
| Ocres and yellow earths |
Composed of clay and silica.
Famous among them:
Sienna earth - manganese dioxide with iron oxide
Burnt Umber - cooked raw umber |
| Kassel earth |
A kind of bituminous earth |
| Red earths |
Verona red, Pozzuoli red, Nuremberg
red, with nuances from orange red to violet red according
to the oxidation degree of the iron oxide in the mineral. |
| Green earths |
Iron hydrosilcate with magnesium
salts and potassium originated by sea clay. The most appreciated
one is the Brentonico green. |
| Blue earths |
With their well known weak resistance
to clay alkalinity. For that reason blues in frescoes were
usually made only with distempers. Giotto's skies are quite
famous even today. |
Earth pigments were ground and dispersed in water before use.
They were left separate from the water which was changed a few
times to take away as much impurities as possible. After that
phase they were blended with milk and thus used in frescoes
or blended with distempers or lime paints.
In ancient times bright colours were obtained from organic materials
like leaves, flowers, fruit, insects, and clams.
Following this phase, oxides became most used. They had similar
shades to the earth pigments but were obtained from the metals:
iron oxide fo ryellow and red, chromium oxide for green, etc.
Today, together with oxides, organic colorants are widely used.
They are obtained form metals (eg: green and blue from copper)
or from chemical synthesis (reds, yellows) which , unlike standard
oxides, result in very bright shades.
Fresco Paint
Fresco painting is a quite simple kind of painting. It must
be made on lime-based plaster before the plaster dries. Normally
such techniqus are used with natural pigments like earth pigments,
washed and blended with milk.
The wet substrate allows for the colors to penetrate deeply
and become one with the plaster.
Encausto Paint
Encausto paint, used by Egyptians, Greeks and Romans, has been
formulated in many different, often contrasting, ways. Even
today's analysis on different works leads to stunningly different
results.
One of the few raw materials which remained common to all those
formulations is the bees-wax.
Encausto comes from the ancient Greek language and means "to
burn". In painting "Encausto" refers to a technique
of blending pigments and wax through heat.
In a nutshell, Encausto is a wax or a distemper using wax as
its main binder. It's difference with the "cold wax technique"
is given by the fact that the former is obtained by applying
the pigmented wax through heat, on a heated wal, after that
the pigment and wax have been blended through heat. On the contrary,
the "cold wax technique" wax is blended with a solvent
(turpentine) and applied on a cold wall.
Today many people refer to Encausto in an inappropriate way,
referring to shiny finishing plaster, both lime-based and synthetic.
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