Color Cement Handicraft 3

Color Cement Handicraft 3

THE OTHER ITEMS OF EQUIPMENT all have their part to play as follows:

 

2 large spoons--For handling plaster and cement.

1 large file or rasp--For occasional use on the tile edge.

3 pieces of glass--On which to cast tiles.

2 table knives--For paring molds, etc.

1 palette knife--For working color into cement.

1 bristle brush--With which to oil molds.

Small modeling tool--To use on clay and plasticene.

Nut picks--For incising.

½ doz. small saucers--In which to mix colors.

Thin soft wire--For cutting molds.

Sifter--To sift cement and color for glazes.

2 pails--In which to mix cement and plaster.

Muller and pestle--Grinding mineral colors with cement.

 

It may be unnecessary to add that the old axiom “A place for everything

and everything in its place,” will do wonders toward keeping the temper

sweet, and a good temper is a most necessary ingredient for producing

good cement handicraft.

 

[Illustration: Tools for Color Cement Handicraft]

 

[Illustration: The Mixing of Plaster-of-Paris]

 

[Illustration: Helpful Material for Color Cement Handicraft]

 

 

 

 

[Illustration]

 

CHAPTER 2

 

The Making of

 

Plaster Molds

 

[Illustration]

 

 

THE SUCCESSFUL USE OF PLASTER is such an important part in the making of

color cement tiles and pottery that as a preliminary step or auxiliary

to the cement craft it should be well accomplished by the student before

using the cement. It is not at all difficult and for those who have not

used plaster, there awaits an interesting medium for all forms of

plastic applications or adaptations. Our concern with it will be in the

making of successful molds for the producing or reproducing of our

cement tiles and pottery, but a whole book could be written upon the

making of plaster objects. The uses of plaster form a large industry and

many art objects are produced in plaster for many forms of applied art.

 

PLASTER IS SENSITIVE to moisture, and should be kept in a dry place. If

plaster does not set within a short time it probably is old and even if

it does set in time it will have a tendency to pulverize. It is always

safer to purchase an entire sack than to purchase a small lot from the

hardware dealer, grocer, or druggist, for the chances are that his

plaster has been exposed in a bin so long that its strength has

vanished. This is mentioned because instances have been known where

trouble in cast making was traced to just such conditions.

 

ON RECEIVING THE SACKS OF PLASTER AND CEMENT the tendency will be to let

contents remain in the sacks. It will be found much more convenient and

economical to empty the sacks into a small barrel or box to which a

cover has been made. A tin tray under the box or barrel will catch all

waste that may drop around the edge, preventing the material from being

tracked over the floor. A nail or hook on the side of the barrel for

holding the ladle or spoon used for taking out the plaster will enable

you to find it when you need it.

 

THERE ARE VARIOUS GRADES OF PLASTER, but the best for this purpose is

molding plaster. The plaster should always be kept in a good dry

location.

 

TO MIX PLASTER SUCCESSFULLY for molds observe the following directions:

A bucket or pan large enough to contain the required amount of plaster

needed should be used. Then half the water for the amount of plaster

used should be poured into the bucket. Sift the plaster-of-Paris through

the fingers into the water, until the water absorbs it no longer. This

can be determined by small portions of the plaster remaining on the

surface. Then stir the whole mass slowly with the mixing paddle until

the passage of the paddle through the plaster leaves a channel which

closes up slowly.

 

IT IS THEN POURED PROMPTLY into the center of the space on the glass

prepared for the plaster tile so that the poured plaster gradually

spreads from the center toward the corners and edges filling up the

spaces and coming up the sides to about one-half inch height. Jarring

the table or a slight shaking of the glass will cause the plaster to

settle very level as well as causing any bubbles in the plaster to rise

to the surface and break. Care should be taken that the plaster is not

too thick before being poured. This stage of the proceedings requires

one having their wits alert, and discussing Futurist art or any other

topic may result in “try, try again.” If the plaster appears too thin

more plaster should be added until it is the proper consistency.

 

After the plaster is poured it should set for about half an hour

(varying according to the dryness of the atmosphere) before any attempt

is made to remove it. Meanwhile all buckets, paddles, ladles, etc.,

containing plaster should be cleaned while the plaster is soft and easy

to remove.

 

WHEN THE PLASTER MOLD IS READY TO REMOVE, a table knife slightly

inserted between partitions and carefully pryed will cause the parts to

separate. A most important part of casting molds and the using of the

plaster molds is the oiling. All parts of the molds to come in contact

with fresh plaster, cement or concrete must be thoroughly oiled or

greased to prevent them sticking to each other. If wood, glass or metal

is used with plaster, cement or concrete, remember to oil or grease such

surface before pouring the plaster or cement on it. If you do not, you

will have to use a chisel and with discouraging results.

 

The best way to oil the surface is as follows:

 

GLASS--Apply salad oil with brush or cloth removing as much as will come

with the palm of the hand.

 

PLASTER BARS AND MOLD should first be soaked in water ten or fifteen

minutes to prevent drawing the moisture out of the fresh plaster or

cement. Wipe off surface moisture with soft cloth, and replace with oil,

before using for molding. If oil is left thick or in brush streaks, it

will leave its influence on the surface of the casting.

 

WOOD--A smooth-surfaced wood should always be used, and oiled well.

 

A good grease formula for all surfaces is as follows: Three parts

paraffin and one part tallow, melt and add one pint of kerosene. This is

applied with a brush.

 

AS AN EXPERIMENT PROBLEM for the use of plaster so as to become familiar

with its use, we will proceed with the casting of a simple flat plaster

tile.

 

Taking a piece of glass, smooth board, marble or oil cloth, brush the

surface with a little salad or lubricating oil, or linseed oil. There

should be no free oil on the surface or streaks of oil as such will

cause an uneven surface. When using glass it is possible to insert a

diagram or pattern of the shape underneath on a piece of paper as a

guide to the bars or retaining walls of the mold. These retaining bars

or walls may be of various materials. Strips of wood or plaster are

excellent and strips of linoleum, metal and even glass are used. If four

pieces of wood about ten or twelve inches long and one and one-half

inches wide are used they can always be adjusted to fit any dimension

from twelve inches down, by being placed as shown in the diagram.

 

TO OIL THE RETAINING BARS, brush the surface to come in contact with the

plaster and then hold the wood in position over the diagram below, using

modeling wax or clay to keep it in position. The clay of course should

always be in position on the outside of the wood and should never be in

the space into which the plaster is to be poured.

 

PLASTER HARDENS SLOWLY IN COLD WEATHER and hardens rapidly in a warm

temperature. Salt added to plaster will cause it to set more rapidly and

to harden more firmly. No exact proportion can be given--just a little

sprinkled in a pan of plaster will cause it to set more rapidly.

 

DIFFERENT PLASTERS SET AT DIFFERENT PERIODS. As has been described

before, casting plasters can be secured in quick-setting, medium-or

slow-setting mixtures. Medium-setting or slow-setting will be found to

be good average mixtures for use.

 

TO RELEASE THE PLASTER TILE after it has hardened (generally a half hour

will insure the hardening action as being completed), the bars can be

released and the tile gently lifted at one corner will cause it to come

apart from the oiled surface. If glass is used the glass can be placed

upright and the separating of the tile from the glass can be watched as

indicated by the moisture suction disappearing as the tile is gradually

separated. If oilcloth is used the tile can be turned over and the

oilcloth peeled off easily. This of course is necessary only where any

sticking occurs, for most times the tile will separate easily. If

sticking does occur it is generally some fault of the oiling for it

needs only one or two little spots overlooked to cause considerable

trouble as the plaster will stick to any part that has been skipped in

the oiling.

 

Plaster dries rapidly and will dry in the sun more rapidly. When plaster

is damp it can be scraped or carved easily. Temperature and the age of

the plaster affect its drying periods.

 

LARGE TILE MOLDS should be strengthened by having burlap strips or wire

imbedded into the back while the plaster is soft. This creates a

stronger layer than where plaster alone is used. Wood strips should not

be used for backing plaster unless thoroughly dried as otherwise it

causes cracking by its shrinkage, and it is best not to use it for

reinforcing.

 

TO CORRECT FAULTS IN PLASTER CASTS use a little of the plaster scraped

from the back to fill in holes or defects. If a corner or portion is

broken off, gouge a hole or cavity so that a little plaster mixed and

placed on that section will become firmly connected. As it hardens, a

little of it can then be scraped with a knife to connect correctly with

the surrounding parts or surface.

 

A SECOND PRACTICE PROBLEM is to take the plaster tile and incise a line

pattern in the surface. To make the incising easier, dip the tile in

water and then trace the design previously prepared onto the plaster.

Pressure alone on the paper with a pencil will make an indentation on

the plaster that can be easily followed in the incising.