2016년 9월 19일 월요일

Color Cement Handicraft 7

Color Cement Handicraft 7


DIFFERENT TEXTURES IN GRAY CEMENT can be secured on the surfaces of
bowls and vases by using almost any of the processes described in the
previous chapter for tiles.
 
IN ADDING COLOR TO DIFFERENT TEXTURES of cement in Cement Pottery the
color or neat cement can be added to the oiled surfaces of the plaster
molds before they are tied together preparatory to the pouring. In this
instance, however, the divisions of the plaster molds should be planned
so as not to break through the designs. If a continuous design motif is
essential, the only way to correct the break will be to touch in the
disconnected parts with the right color or mixture after the parts of
the mold have been placed together just previous to the pouring in of
the slip for the first rotation.
 
THE MAKING OF FLAT BOWLS simplifies the rotating problem and in many
shapes the slip can be placed and directed with the use of a brush.
After the last slip has been added to a bowl, a design can be added with
a brush by using a different color, placing the color slip in the center
of the inside portion of the bowl. This can also be done on the outside
surface of any bowl or vase, creating a change and surface enrichment.
 
VASES WITH SQUARE SIDES should be produced from plaster molds which have
the connecting lines coming on the corners. In this way the casting
lines that always show to some extent on the cast surface when it is
removed from the mold, will occur where it will be easy to remove them
and if a little does remain it becomes a part of the corner.
 
If any incised lines or relief parts are on the sides of these square
formed vases, a separate piece for each side will be necessary in the
plaster mold.
 
A GLAZED FINISH can be produced by rotating a bowl or vase in a mixture
of neat cement that has been well sifted and placed in a pan in a thick
enough layer to permit the bowl or vase to be turned in it without the
sides scraping the bottom of the pan.
 
WHERE LARGE RELIEF SURFACES are to be produced and undercut surfaces
molded, it is then necessary to use glue for the molds. This requires
skill in handling. For those who wish to produce molds for such work the
following is given:
 
After modeling the surfaces or figures in relief, if they are to be used
on garden pottery, book-ends, vases, etc., or any design that has
undercut surfaces, it should be covered over entirely with a one-half
inch layer or blanket of wet clay or modeling wax. If the modeling has
been done in clay it should remain overnight without the usual wet cloth
over it, before placing this second clay layer. If wax is used the clay
layer can be placed over it without waiting. Deep sections should be
lightly filled with clay to reinforce the one-half inch layer. Two or
three nails should be used to hold the original firmly to a board base.
A little plaster-of-Paris should be poured around its base to help make
it firm.
 
Over this clay blanket lay a strip of clay along the highest part or
equator of the surface, so that the surface is directly in line with the
equator. Place a casing around and fix so that plaster can be poured,
and a rough casing produced of one half. Remove the clay strips and with
a pointed piece of metal bore several holes or “keys” in the exposed
edge of the plaster. Oil this edge and cast the second half.
 
Before pouring the plaster a clay cylinder should be placed at the top
to form a hole for pouring into and a second hole near it for an air
escape.
 
After the plaster is set it will be found that a casing or shell is
produced which when placed over the original model (the one-half inch
clay blanket having been removed) will leave a space around the entire
original model.
 
The next step is to prepare the casings and pour the glue into this
space to produce a mold of the object and its immediate surface.
 
A few pencil marks are made on the outside of the casing and carried
onto the table or board base to check up its relation when it is
replaced. These marks are very necessary.
 
The casings are then given two coatings of shellac and wood alcohol (one
part alcohol, three parts shellac), and when dry are oiled well or
greased with axle grease. Shellac is also applied to the original model
whether clay or plaster. Plasticene or similar wax need only be oiled
slightly.
 
Replace the cases so that the two halves come together closely and so
that the marks on the outside lower edge correspond correctly with the
marks on the table. Stop the cracks on the casing with clay dipped in
plaster and bind over the casing in the same way (or with the use of
cords) to prevent the glue from floating the casing.
 
THE GLUE IS PREPARED as follows: White fish glue or gelatine glue is
washed well in water. Put in dry can, placing it in second pan of water
and boil until creamy in consistency. When the finger can be dipped into
it without burning, the glue is poured into the casing as follows:
 
A funnel of clay or wax is roughly made and the glue poured into the
opening of the casing, filling the space between the model and the
plaster casing.
 
Let stand for twelve hours. Remove casing and cut the glue shell along
the half-mark made by the equator division, cutting from the under side
through at one stroke. The glue can be lifted (as it will give) so as to
permit cutting from underneath. To cut from the outside will not produce
a clean cut.
 
With French chalk or talcum, chalk the inside of the plaster casing well
over the shellac and fit the glue shells back into each half. Then with
a solution of powdered alum and water (two teaspoonfuls in one-half cup
of water) brush the entire inner surface of the glue to harden the
surface. Let stand for one hour.
 
IF CEMENT IS TO BE USED, the glue must receive two coats of white lead
or varnish and left to dry two days. When plaster is used no white lead
or varnish is necessary.
 
Cement should be used thin and a thin layer produced by pouring into
this mold and revolving it so that a coating will stick to the surface.
After setting for twelve hours more is added and again revolved until
the desired thickness is produced.
 
Where the object is not to be hollow the cement is poured in solid and
left until hard enough to remove the casing and glue shell.
 
This sounds complicated but it is no harder than the usual recipe and if
you can’t follow a recipe or be interested in its result, then there is
no hope for you in Color Cement Handicraft.
 
A DIAGRAM ILLUSTRATING GLUE MOLDS is shown at the end of Chapter Two, on
The Making of Plaster Molds. A little study of this with the above
directions will make the process clearer.
 
[Illustration: Vase Molds]
 
[Illustration: The Finishing of Cement Pottery]
 
 
 
 
[Illustration]
 
CHAPTER 5
 
The Use of Color in
Cement Tiles
 
[Illustration]
 
 
SUCCESSFUL COLOR IN CEMENT WORK is dependent entirely upon the use of
mineral pigments in dry powder form. The lime action in the cement will
nullify and disintegrate any color of a vegetable or chemical source so
that no hue remains.
 
A LIMITED RANGE OF COLORS is therefore presented to the worker in Cement
with which to secure results, but the list of colors described in the
following paragraph is after all an elaborate one when compared with the
few pigments with which the primitive and aboriginal potters produce
most beautiful results in their wares.
 
PICTORIAL OR REALISTIC DECORATIONS ARE NOT DESIRABLE as Color Cement
decoration and it is hoped by the authors that those who follow the
technical direction of this book will be in harmony with the applied
design principles set down in the last chapter; and that their color
cement productions will be such that it will add correct line, form and
color to this new handicraft. This will enable its growth among the art
handicrafts to be without handicap or prejudices resulting from its use
in incorrect design or application.
 
THE FOLLOWING COLORS ARE POSSIBLE in mineral colors for us in Color
Cement: Black, Brown, Red, Dull Yellow, Blue, Green.
 
A Color Scale and Mineral Colors are as follows:
 
{ Germantown Lampblack
Black or Gray { Carbon Black
{ Black Oxide of Manganese
{ Black Oxide of Copper
 
Blue { Ultramarine Blue
{ Oxide of Cobalt
 
Yellow { Yellow Ochre
{ Chromate of Lead
 
Orange Mineral Orange
 
Green { Chrome Oxide of Copper
{ Carbonate of Copper
{ Roasted Oxide of Iron
Brown { Burnt Umber
{ Metallic Brown
 
{ Indian Red
Red { Venetian Red
{ Mineral Turkey Red
{ Raw Iron Oxide
 
THE SUCCESSFUL USE OF COLOR IN CEMENT depends entirely upon the true
proportion of color to the cement. No exact rule can be quoted as colors
vary in quality in different localities. Experimenting only can solve
the correct proportions. Also, anything that will nullify the action of
disintegration upon the color by the lime in the cement is desirable.
The Petroma Cement Colors made by the American Crayon Company of
Sandusky, Ohio, fulfill these requirements for the craftsman, and will
aid in successful schoolroom results, avoiding loss of time and waste of material.

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