Color Cement Handicraft 6

Color Cement Handicraft 6

Where a concrete mixture is to appear rough in texture, the sand or

gravel and cement should be mixed dry, just enough water added to cause

it to mix up to a damp consistency so that it can be shaped with the

hand. This can then be put in the mold and tamped slightly with a block

of wood to press it in true contact with the surface of the mold. This

will result in a porous, open texture, producing good contrast with neat

cement parts that have been previously placed or are to be added.

 

THE CEMENT AND CONCRETE TILE is made with plain cement producing added

interest to the design by the two textures or surface finishes that

occur between cement and concrete. The design for such a tile is best

where the parts are separated either by an incision or a relief line.

The plaster mold should therefore present separate portions, some of

which can be considered for the cement parts and others for the concrete

parts.

 

By mixing neat cement until it is of a thin mixture, the mixture can be

placed on the mold wherever wanted by dripping it from a brush. Care

should be taken in the use of a brush with cement that a wiping stroke

is not used as such a stroke will remove the oil from the plaster

surface and cause parts of the cement to stick to the plaster.

 

After the cement has been placed, a concrete mixture is made and poured

into the space up to the desired height to produce the necessary

thickness. This will at the same time fill in the remaining surface

spaces of the tile.

 

THE GLAZED AND DULL CEMENT TILE is produced by filling in with clay or

glued cardboard bits cut to shape, those parts that are to be glazed

gray cement. Do not use modeling waxes or artificial clays for this part

as the oil or grease in them will interfere with the glazed cement

adhering to the surface in the final finishing.

 

After the cardboard or clay is dry a layer of neat cement is poured in,

and backed with the usual concrete mixture. After the tile is released,

the cardboard bits or clay is removed and cleaned out, the surface under

it is roughened with scratched lines and the tile is put in water for an

hour. The spaces are then filled with a mixture of neat cement and

permitted to harden in a shallow tray of water.

 

TO MAKE GLAZED CEMENT SURFACE it is important that these steps be

watched:

 

1st. That the surface be roughened wherever the glazed surface is

to appear.

 

2d. That the tile be soaked in clean water until it has fully

absorbed water.

 

3d. That a little dry neat cement be placed on the spaces to have

glazed effect.

 

4th. That the neat cement should be sifted and dripped on with a

brush and not gone over a second time.

 

5th. That the tile is taken out and dried and the glazed and dull

neat cement will create the change of surface texture as planned.

 

A bloom or chalk-like powder often comes on the surface of tiles, but

will disappear within a short time and need not cause any anxiety.

 

GLAZED RELIEF LINE TILE is made by casting either a neat cement tile or

a concrete tile with a relief line design and then mixing a neat gray or

color cement glaze and putting it onto the surface. The tile is shaken

in a level position until the entire surface is entirely covered leaving

a thin layer of the glaze in the spaces between the lines as well as

slightly on the lines. The tile is set in a shallow layer of water to

harden.

 

OTHER VARIATIONS IN TILE EFFECTS can be made by combining these methods

and with the use of color in these different methods described,

unlimited avenues are opened to the worker in color cement. It should be

remembered also that most of these methods of surface treatment are also

possible in other forms beside flat or tile surfaces. The student should

know these methods of working with plain cement and concrete as they are

the foundation of successful Color Cement Handicraft.

 

[Illustration: How to Make Color Cement Tiles]

 

[Illustration: Cement Tile Textures]

 

[Illustration: The Incised Tile]

 

 

 

 

[Illustration]

 

CHAPTER 4

 

Making

Vases and Bowls

 

[Illustration]

 

 

MAKING VASES AND BOWLS is a little more complicated than the making of

tiles, but by following the directions carefully it will be found that

once the process is worked out, it can be easily repeated.

 

FOUR DEFINITE OPERATIONS are necessary to produce a bowl or vase and

they may be termed as follows:

 

1st. Making or preparing the original model.

2d. Making the molding case from the model.

3d. Pouring the concrete into the molding case.

4th. Releasing the mold and completing the object cast.

 

THE FIRST STEP, making the original model, is as follows: With clay or

modeling wax build a form of the vase or bowl desired. The inside need

not be considered; that is, do not make the form hollow but build it

solid. Care should be taken to see that the contour is even and alike

when viewed from all sides. A templet cut from metal, wood or stiff

cardboard, will help in securing perfect contour if moved around on the

outside and corrections made accordingly. A false neck should be added

onto the solid form and part of the bottom of the mold scraped so as to

leave a rim or edge on the bottom. The form is then ready to make a mold

from it.

 

ANY VASE OR BOWL CAN BE DUPLICATED in cement by making a plaster mold

from it. The inside of the bowl should be filled with sand or wadded

paper and a false neck built over the mouth with clay or modeling wax.

If the surface is glazed it need not be oiled before casting, but all

dull or rough surfaces should be oiled.

 

THE SECOND STEP, making the molding case, is as follows: Take the model

(clay or vase to be duplicated) and place it upon an oiled glass or

other smooth surface. Marking off about one-third of its diameter, build

a narrow strip of clay or wax on two sides from top to bottom. This

ridge or wall should extend far enough out to meet the molding case or

metal strip, and the two walls of clay and the metal or case should be

made proof against the plaster running out anywhere, when it is poured

into this well. After the plaster is set, the clay strip can be removed

from one side and the exposed plaster edge is oiled after two keys have

been bored into it with a pointed metal strip (see working plate). The

removed strip is then built along the next division of the model and the

case or metal used for retaining wall is moved into new position and a

second third of the molding case is made. To make the third or last

piece of the mold the two first sections are retained in position

(always boring keys and oiling exposed edges), the case or metal wall

again placed in position and the plaster poured into the opening. The

plaster should not be too thin and if a little is poured into the bottom

and allowed to set before pouring the whole amount, it will not be

forced out through the bottom. Of course all openings must previously

have been stopped with clay or wax.

 

TO STRENGTHEN A MOLD strips of burlap or wire screening can be imbedded

in the plaster while it is soft. This makes a durable mold capable of

withstanding much handling.

 

TO MAKE THE MOLD FOR THE BOTTOM the three sections are turned upside

down (the model still being in position) and the plaster parts all being

oiled, a ring of clay is placed around the bottom so as to make a cup

shape into which the plaster is poured.

 

THE THIRD STEP is the most important part as the mixture or “slip” for

the pouring is important. The first mixture should be neat cement and

water and should be rather thick, for if too thin it will not adhere to

the walls of the mold. When the neat cement is ready it should be poured

into the bowl about half-way full. The bowl is then rotated in a

horizontal position gradually downward so that the surplus cement slip

will pour out of the mouth back into the pan or container in which it

was mixed. Then after a half-hour or so another mixture of slip should

be rotated. This mixture should be composed of a one-third cement and

two-thirds sand mixture and be thinner in consistency. If the bowl is

large and the walls need to be thick a third and fourth layer may be

necessary.

 

THE LAST LAYER OF SLIP can be of neat cement which will finish the

inside with a smooth surface. When working with color the first rotation

and the last may have color added to the slip which will result in a

color finish on the inside and the outside of the bowl or vase.

 

THE FOURTH STEP or releasing the mold, should occur the second or third

day after the pouring has taken place. This elapse of time depends all

upon weather conditions. In summer cement dries more rapidly and not so

well. In winter the hardening is more slowly accomplished but more

perfectly.

 

THE DRYING OF CEMENT is best when it occurs gradually. Never place

cement in the sun or use artificial heat to force it. Checking, cracking

and breaking will surely result if this is done.

 

For this reason the tiles and pottery made with cement should dry

gradually in the shade but not in a draughty location.

 

To release a vase or bowl from the mold, the cords are untied and the

plaster mold parts opened. The cement cast, if successful, will separate

from the mold without trouble. The ridge that may have been formed by

the groove where the plaster parts have come together can be scraped off

and smoothed by rubbing the finger tips over the surface. The surplus

part of the neck can be carefully scraped away and after the vase has

dried out of the mold for a day it can be put in a bucket or tub of

water to harden for a few days or a week.

 

TO FINISH A VASE it is removed from the water, permitted to dry well,

the surface is brushed clean and it can then be waxed or surface

finished as described in another chapter of this book.

 

A RELIEF DESIGN ON A VASE SURFACE requires care in making the sections

of the mold so that the vase cast will pull out of the mold without

breaking. If the molds are made in three or four segments there is

little danger of trouble but wherever there is relief surface or lines

on the surface, a two-piece mold is sure to result in the breaking of parts.