Color Cement Handicraft 2
After a study some years ago of the various forms of producing clay
pottery and its possible relation to school arts and industrial
education, the handicap of necessary firing to give permanency loomed
large against its general adaptation by schools. This resulted in
considerable research and experimenting by the authors with cement and
the use of color in the endeavor to parallel in some measure each of the
methods employed in the making of fired tiles and pottery. Particular
attention was given to simplifying the process of securing permanent
form to many of the plastic forms of schoolroom art, which have been
presented in clay and other perishable mediums. With the projects
presented in the following chapters permanent useful objects can be
secured by students in their school art subjects. Attention was also
given to the enriching or refining by decoration the many objects
heretofore made in cement and concrete by vocational classes. The
problems and methods explained in the following description solve this
need.
Craftsmen or amateur home-workers who delight in creating and building
objects of beauty around them can find in color cement a medium which
will appeal to their needs, in that the necessary working equipment is
simple and the work can be done within small space.
The following chapters by no means complete the story of color cement.
They record the results of the work of the authors and it is hoped that
it will stimulate interested readers to carry this delightful handicraft
to even greater achievements.
The results achieved have been accomplished through several years’
patient experimenting by the authors, but the realization that many
other teachers, craftsmen and students will be aided in continuing this
delightful, durable handicraft, is in itself an enjoyable reward to the
authors for their efforts.
Reta A. Lemos
Pedro J. Lemos
[Illustration]
CHAPTER 1
Materials and Equipment
[Illustration]
IN THE MAKING OF COLOR CEMENT HANDICRAFT the chief material used is
Portland cement. While this material has assumed a most important part
in the building history of our present time, there are not many who know
its history and source, and as every craftsman is a better craftsman if
he knows something of the story of the material with which he works,
here is the brief story of Portland cement.
PORTLAND CEMENT DERIVES ITS NAME because of resemblance in color to a
stone quarried near Portland, England, and it was named by its inventor,
Joseph Aspdin in 1824. It is a manufactured product produced by a
scientific process. At the beginning of the Christian era the Romans
used a natural cement very extensively, and many fragments of color
frescoes and friezes remain from the work of the ancients, showing that
they used color with their work.
THE PRINCIPAL INGREDIENTS OF PORTLAND CEMENT are lime, silica, iron, and
alumina. These materials are mixed in definite proportions and then
subjected to a degree of heat that almost causes them to melt, forming a
clinker or slag. This clinker is ground until it is reduced to a powder,
and this is the Portland cement. Portland cement is generally mixed with
an aggregate to produce strength and this aggregate is usually stone,
gravel or sand. The third material needed to complete the combination is
water.
SUCCESS IN THE USE OF CEMENT depends largely upon cement that is fresh.
Cement is very sensitive to moisture and if kept where fogs, dew or
moisture of any nature is absorbed into it, the first set or “hydration”
takes place and destroys its use for fine handicraft.
TO TEST FRESH CEMENT when the cement sack is open, thrust the hand into
it and see that no hard lumps are in it. Fresh cement will feel
slippery and soapy when rubbed between the finger tips. If it feels
gritty and sandy it may do for the rough parts or body of vases and
tiles, but only fresh cement should be used to mix with color and for
surfacing purposes.
THE PROPER CARE OF CEMENT requires that it be kept in a covered
receptacle and kept in a dry place, preferably up from the floor if the
floor is near the ground. It should be kept in a dry, tight work-shop
and the doors should be kept closed at night to avoid any moisture from
the night air reaching it. Nothing can restore spoiled cement and it
should not be used as the results will be discouraging.
GOOD GRADES OF AGGREGATES SHOULD BE USED in cement work. Clean sand
should be used and a sand that is not too fine is preferable. Gravel and
crushed rock used in large work such as garden seats, large bowls and
outdoor problems should be of a good grade to form a good mixture.
THE WATER USED IN CEMENT WORK should be free from all impurities.
Moderately warmed water will hasten the setting or hardening of cement
while very cold water retards the hardening.
THERE ARE TWO COLORS OF CEMENT, gray and white. Portland cement is gray
in color and a white cement is also made that is a refined form of
cement. White cement is not as hard or durable as gray cement, but gives
a smooth surface and sets as satisfactorily as the gray cement. It is
more expensive than the gray cement and should not be used later than
six months after the sack is opened.
WHEN CEMENT IS USED ALONE IT IS TERMED “NEAT.” When it is mixed with
rock, gravel or sand it is termed “concrete.” Concrete produces strength
and the neat cement produces a smooth texture and surface. When concrete
is used the cement and water will rise to the top and if the surface is
worked and pressed with a trowel the cement is “flowed” to the top,
producing a smooth surface.
MOLDS ARE USED FOR FORMING CEMENT AND CONCRETE, and are made from wood,
metal or plaster-of-Paris. The forms in all instances should be tied or
braced together to prevent the moisture of the mixture from running out,
as the water is essential to the successful hardening of the cement. In
the making of cement pottery and tiles, plaster-of-Paris molds or forms
are generally used and plaster-of-Paris therefore forms an important
material in the making of color cement handicraft.
Plaster-of-Paris is made in different degrees of setting periods. These
are quick-setting, medium-setting, and slow-setting. Casting plaster or
sculptor’s plaster should be asked for and a medium-or slow-setting
plaster is preferable for the beginner.
CEMENT, AGGREGATES, WATER AND PLASTER FORM THE MAIN PARTS of our working
materials excepting the color, which is especially described in the
chapter on Color.
THE EQUIPMENT for concrete pottery is simple, and much of it may be
pressed into service from material to be found about the house or
workshop. Inventive ingenuity on the part of the worker will find clever
uses for many discarded kitchen utensils and unused tools.
Following is a list of convenient things needed to produce pottery.
These may be added to or elaborated through personal requirements.
WORKING EQUIPMENT.
galvanized iron pans about 2 x 3 feet
2 large spoons
4 or 5 pans
2 ladles
1 large file or rasp
2 table knives
3 pieces of ordinary glass about 12 x 18 inches
1 palette knife
1 lb. modeling wax
1 bristle brush ½ inch wide
2 small sable oil brushes, No. 1 or 2
1 small clay-modeling tool
2 pieces of thin wood for mixing paddles
½ doz. small saucers or butter dishes
strips of thin metal
thin soft wire
1 sifter
2 pails
muller and pestle
several pieces of surfaced wood about 12 inches square.
With a flat table to work on, running water or a pail of water handy, a
box to receive waste plaster-of-Paris and cement, the proper environment
for color cement is set.
GALVANIZED IRON WATER TRAYS can be made by taking a three-inch by
seven-inch sheet and cutting a two-inch strip off of one end, reserve
for making scrapers and other useful tools. Cut the remaining metal into
three rectangular sections for trays.
To make the trays, lay one of these pieces over a strong box with an
even edge and hammer into tray shape as shown in the accompanying plate.
The corners should be bent so as to make the trays waterproof without
soldering. A wooden mallet should be used for hammering the metal as a
metal hammer may cut the metal.
MOLDING CASE. Several pieces of board hinged together with one series of
edges coming so that they will rest evenly on a flat surface, will
produce an adjustable case to use in making molds. A strong cord will
keep it in place. A strip of metal (tin, brass or iron) may be used as
a cylinder, the circumference being pressed in and tied to conform to
the dimensions of the object to be molded.
MIXING PADDLES. Paddles for mixing plaster or cement can be made out of
firm wood strips and handles shaped to fit the hand.
INCISING TOOLS. A nail hammered into a piece of firm wood and the head
snipped off with nippers then sharpened with a file or emery stone until
it is a tapering wedge point. Nut picks may be filed down slightly for
this purpose. Two or three points of varying widths will be handy to
have, particularly when some of them disappear occasionally as all small
tools will.
SCRAPER. A piece of barrel stave or heavy wire bent like a croquet
wicket with a wire fastened from end to end is particularly convenient
where a number of clay or plasticene tiles are to be produced. For class
use two strips of wood are fastened to the bench, the desired width
separating the strips. Between these strips a piece of strong paper
should be laid and the clay or plasticene pressed firmly onto it between
the strips. The scraper will shave the surplus clay if it is moved along
so that the wire rests on the wooden strips. Measure off the six-inch or
eight-inch squares, cut across with a knife from strip to strip and
remove the squares by sliding the paper out. This will give a smooth,
even surface on which to model or incise designs.
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