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.