© Michael Price Inc.
azurite crystals
Vivianite and Purpurite

Vivianite makes a fascinating pigment. After being crushed
and ground it has to be levigated in a weak casein solution
before being mulled in oil. Otherwise some discoloration in a
paint layer will be evident after about five years. It separates
easily into at least three grades from about 70-80µm down to
a fine powder of 10-15µm. The fine powder as well as  
medium size particles of 40µm can be used as a glaze over
malachite imparting a rich dark bluish hue to the layer of
green.
Purpurite, even of a low grade, produces a distinct rich and
sometimes purplish brown which brings amazing luminosity to
dark passages in a painting. No brown earth pigment can
match its characteristics.
lapis lazuli crystals, Afghanistan
malachite, pollished and crystal
orpiment, realgar and yellow ochre
Realgar and cinnabar crystals
Pyrolusite, Stibnite, Galena, Purpurite and Vivianite
Lapis lazuli
Malachite
Orpiment, Realgar and Yellow Ochre
Realgar and Cinnabar
Pyrolusite, Stibnite, Galena, Purpurite and Vivianite
Azurite
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Preparation Protocols for Mineral Pigments
Technical  details for the artist and restorer
Azurite (blue copper carbonate)
I usually prepare 10 to 14 grades of very pure azurite from
approximately 10µm to over 100µm. The crushed and washed
azurite is levigated two to three times through a casein
solution according to the purity of the rock specimen. With
azurite, the evenness of the pigment particle size in each
grade is crucial to the end colour result. Layering with
different particle sizes will result in different hues and tones of
blue.
Natural Ultramarine from Lapis lazuli

Tests show a very pure lapis lazuli from the protocol I
developed in 2010. The process is quite different from the
method described by Chenino Cennini.
I now include the Cennino Cenni method in workshops.
Malachite (green copper carbonate)

Malachite is similarly sensitive to the acid in an oil binding
medium, but the discoloration is not as noticeable as with
azurite. Malachite is prepared in either a casein solution or
diluted egg yolk solution according to the pigment particle
size. Below 30µm it should be prepared in casein. With a
particle size of 30µm to 80µm, an egg yolk solution of 1 part
egg to 2 to 3 parts water can be used. There is a point in the
dilution of the solution that the typical malachite green is
instantly changed into a deeper and richer green. The change
of hue is only minimal with a casein coating of the pigment
particles.
Orpiment, Realgar and Lead-Tin Yellow

The unprepared pigments of either orpiment and realgar with
lead-tin yellow will react chemically if mixed or come into
direct contact with each other in a paint layer. I have been
able to develop a layering of these yellows to produce a very
powerful and luminous „middle“ yellow. The orpiment and
realgar are both prepared in casein solutions and must be dried
out for a minimum of one week before use. The lead tin
yellow is soaked in a weak warm solution of rabbit skin glue
size and allowed to dry for the same time before being mulled
in either linseed or walnut oils.
Cinnabar

This mineral varies considerably in quality, but nevertheless,
pigment of similar quality can be extracted. Preferably
specimens such as the pieces of cinnabar (bottom right) should
be used. The rock crushes quite easily and care should be
taken not to turn it into fine powder too quickly. This will
make it more difficult to remove impurities. Optimal
levigation is in a weak casein solution. It will take a couple of
days for the finest orange particles to settle out of solution.
The finest pigment will give the most spectacular orange-red
in a co-polymerized linseed oil.
Page 2
Selection of Crystals and Minerals
The images on this page are examples from the two volume
book: "Renaissance Mysteries, Vol. I: Natural Colour and
Volume II: Proportion and Composition".

For further information go to:
renaissancemysteries.com