..the method - you will prepare a plaster surface
on the unglazed side of a ceramic tile. while the plaster is till fresh
you will paint a design of your choice using pigments prepared in water.
you may use pigments you have synthesized or pigments from Kremer, the best
known supplier of artists' pigments. you should paint two tiles, one to
keep and one to "destroy". next week we will investigate the conditions
that lead to fresco deterioration. there are various sizes of tiles available.
it is advised that you use the smallest tiles for the deterioration tests.
of the tiles - variously sized tiles have
been soaked in water for more than 24 hours and are ready for receiving
of the plaster -
you should prepare the plaster with another student, in pairs. mix
one part sand and one part
pit lime in the plastic tubs. you may use a spatula or a hand in a
plastic glove. mix the two components well until homogeneous and pliable.
..apply the intonacco layer -
remove a tile from the water bath and allow it to drain and dry slightly
until the unglazed surface
acquires a matte surface. apply the plaster with a spatula or scoopula,
spreading it to make a thin layer (about 1/8 - 1/4 inch thick). a layer
that is too thick will crack on drying. smooth the surface using the curved side of a scoopula, passing over the surface in
one direction then again at a right angle to the first pass.
..painting the design - you should think in advance of
how you wish to paint yoru design. you can paint freehand or, you can
transfer a pre-drawn design by "pouncing" or tracing. pouncing involves
making your design, punching holes that will define the lines of yoru
design, then :pouncing" dry pigment through the holes to outline the
desine on the fresco. tracing can be done using a pencil or blunt object
to trace over the lines of the design, slightly scoring the surface
of the plaster beneath the design on paper.
the plaster must evaporate much of the excesss water before applying the paint. it is
ready for painting when a brush loaded with clean water is passed over
the plaster and does not score it and the plaster absorbs the water.
the drying time prior to painting can take 10-20 minutes, depending
on the humidity of the room and the moisture in the plaster.
while waiting for the plaster to dry, you can continue
to plan and prepare your pigments. pigment ay need to be ground—"mulled"—with
water in a mortar and pestle to make a pigment /water suspension. there
is also a glass muller and polished marble plate for you to try mulling
pigment. the paint is ready when a drop in a vial of water
floats (mostly). the paint should be applied as a rather dilute wash,
rather than a thick paste. one method of accomplishing shading and
shadow effects is to first paint the darker portions representating
shoadow, then paint a wash of the lighter color on top of the shadow.
the paints will be transparent and require several coats for intense
colors. allow ~15 minutes between coats.
..note!! - some pigments are chemically
incompatible with the very alkaline medium of the plaster. prussian
blue in particular
will change color over a week and fade from blue to dull green. good
choices for long term stability are any ochres, ultramarine. carmine lake is likely to fade as well.
..fated for destruction - on
the small tile whose fate is to be less than beautiful, be sure to
include lead white, ultramarine,
azurite, malachite and verdigris pigments in your painting
For this studiolab you will do the following:
- use lead white, azurite, verdigris and malachite to paint a small
watercolor. This watercolor will be placed in a small plastic bag with
sodim sulfide solution.
- make observations about the putting small amount of the follow salts
- sodium carbonate
- barium chloride
- barium chloride added to an already prepared solution of sodium
- chip off an edge piece of your fresco and place it in hydrochloric
acid. Do the same with a piece of marble.
- depending on the pigments in your small fresco, you will place
it in a plastic bag with an acid or with sodium sulfide.
Details for doing the above tests will be given in lab.
** It is very important to make careful observations this week and
note them in your notebook.
is devoted to your exploration of five different media—acrylic, oil,
tempera, watercolor and pastel. In order to work with all five binder media,
and especially if you wish to create your own art using one or more
of these media, it is essential that you arrive prepared
and with a plan. Read the following instructions carefully.
At each of the
four benches in the lab will be the materials to prepare one type
of binder. As detailed below, you will either prepare the binder
mixture alone for your individual use or, your group at the bench
will prepare enough binder for all the group to use to mix paints.
The procedure for making each type of binder media and paint is described
Do this individually. Three
types of acrylic polymer binder are available. One dries to a gloss
finish and the other
5 of each acrylic polymer suspension in a small plastic cup. Note
its characteristic odor, color and viscosity.
Combine 4 mL of linseed oil with 8 mL of turpentine in a paper
cup. Stir well. **There is also walnut oil an dsafflower oil if you wish to see how oil paint from these oils differs.**
2. Describe the color, texture and viscosity of the binder.
this in individually.
Obtain one egg. Separate the egg yolk from the white. Discard the
egg white in the sink. Place the yolk in your palm and pass it
palm to another until the yolk sac becomes fairly dry. Puncture
the yolk and drain it into a small lastic cup.
2. Add an equal
volume of distilled water to the yolk. Stir the mixture into a pale
3. Describe the color, texture and viscosity of the binder.
here are other recipes for tempera, in case you want to experiment
more with these later.]
Do this as a group.
1.Place about 4
mL (1 teaspoon) of water in a small plastic cup, add about 4
g (1 teaspoon) of table sugar and stir to dissolve.
2. Stir in 6 mL of glycerol (glycerin) and 20 mL of the previously
prepared gum Arabic stock solution. Add 1 drop of a lab detergent
(soap) and mix well.
3. Describe the color, texture and viscosity of the binder. Save and label this to conserve the watercolor binder for use by other groups.
the Paints. The
pigments, especially those you synthesized several weeks ago,
need to be crushed and finely ground before mixing with the binder. Use
porcelain mortar and pestles for grinding, and please re-use mortars
already stained with a particular pigment (like prussian blue). Place
a small pile of pigment on glassine paper and add 5-10 drops of binder
then mix with a spatula, repeatedly rubbing the pigment/binder paste
with spatula to ensure even coating of the pigments particules by the
binder. For acrylic paint, first mix the pigment with water, then add
the acrylic binder. This serves to aid dispersion of the acrylic media
around teh pigment particules.
to use in making paints? You are free to use any pigments available
in the lab as well as those you synthesized. It is recommended that
you make paints using all four types of binders with a set of the
same 2-3 pigments ( for example Prussian blue, chrome
and ultramarine) to see the differences in paint appearance and behavior
in the different media. You may make up additional paint colors and
create a painting as time allows. An efficientcy tip: grind up enough
pigment to be used in all four binders.
Do this as a group.
pastel sticks involves trial and error in order to obtain the
desired properties. Getting
a good pastel stick involves mixing just the right amount of
binder and pigment. This is where the experimentation comes in. This is because
different types of pigments need different strengths of binder
for optimum working properties of the pastels.
The first step in making the pastels is to prepare a dilution of
the stock gum Arabic binder.
Preparations of Gum Arabic Binder Solution
1. Obtain a plastic cup. Measure out 10 mL of gum Arabic stock solution
into one of the cups.
2. Add 20 mL of water to this solution. Mix well. Save and label this to conserve the gum binder for use by other groups.
Procedure for Making Pastels
1. Place about 1-2 teaspoons each of pigment and Kaolin on a clean non-porous
surface (wax paper). Mix them together.
2. Add a small amount of the diluted gum Arabic binder, a few drops at a time, to make a doughy consistency.
3. Work the pigment and binder together with a spatula until the mixture
has a rubbery consistency. If it is too wet it sticks to paper and if
it's too dry
it will fall apart. If you add too much liquid you can add a bit more
pigment and Kaolin mix.
4. Roll the dough on paper until it is the shape you want. Allow the
sticks to dry for a day or two before use.
Synthesis of Perkin's Purple Dye Mauveine
see handout for procedures
Measuring Color: Spectroscopy
Objectives for today:
1. what is spectroscopy
2. how it quantifies color
3. what is meant by light absorption, reflectance, transmittance
4. how to generate a reflectance ( transmittance) spectrum from an
absorption spectrum and vis versa.
5. how broadly spectroscopy can be applied, e.g., how infrared spectroscopy
1. run at least one visible spectrum of purple and plot as absorbance
and as transmittance
run (with help) an infrared spectrum of phthalocyanine; 2) run visible
of different watercolors
3. Clean-up lab
What pigment was used?
Identify what pigments are in my painting
the method: Microscopy
a) identifying isotropic vs. anisotropic pigments
b) chemical reactions
the strategy: Get familiar with microscope.
a) Look at NaCl (isotropic) then cross polarizers. (put few crystals
in smear of oil to fix)
b) Look at (TEA)2MoS4 : anisotropic: see what happens under crossed
c) Look at azurite: anisotropic.
d) Look at ultramarine: isotropic
Test chemical reactions:
a) Azurite and
b) Prussian blue and NaOH
c) Ultramarine and HCl
d) Cobalt blue and either
Plan your strategy.
a) Mark location
of sample on copy of picture.
b) Take at most 2 samples. Use knife; have slide ready with oil smear
c) Place "authentic sample" on slide too for comparison.