Sgraffito
Color Cement Work
[Illustration]
SGRAFFITO is the name applied to the incised ware of the Italians, and
used by them from a very early period dating as far back as the twelfth
and thirteenth centuries. The ware was made by covering the clay body
with a layer of slip of another color, and this was then scratched
through with a tool showing the color of the ware beneath against the
superimposed surface, after which it was fired. This process has been
used from the most primitive times, but it remained for the Italians of
the fifteenth century to dignify it as an art.
COLOR CEMENT SGRAFFITO is produced with a layer of cement and color
being used instead of colored clay and the cement is hardened without
firing, water only being used to finish the surface to a durable
quality.
THERE ARE TWO WAYS to produce a sgraffito surface on a tile and these
are, the glazed surface and the dull surface tile. No mold is needed for
the design as a sgraffito design must necessarily be a freehand
production, though molds may be used for duplicating the sgraffito
effect after the original one has been made, if no undercut edges are
left.
TO PRODUCE A SGRAFFITO TILE, the retaining bars are set to give the
desired shape and dimensions, after which the space is filled with a
half inch layer of concrete, either of sand and cement mixture or of
gravel and cement. When this layer has dried so that the top section is
moist but firm in surface, a thin layer of color and cement should be
poured onto the cement so that it forms a thin layer not more than an
eighth of an inch thick.
TO SMOOTH THE LAYERS after the color has been poured in, shake the glass
or table or whatever surface the mold is resting upon and if this is
done gently it will cause the color to become level and even in surface
finish.
TO CAUSE TILES TO BE EQUAL IN THICKNESS the surface of the glass or
table upon which the mold rests should be level when the cement is
poured in. Otherwise the tile when finished will be found to be thicker
on one side than on the other. A glass or pan of water or a spirit level
will quickly show whether or not the surface is level.
AFTER THE FIRST COLOR LAYER IS POURED into the mold it is permitted to
stand just long enough to settle firmly and then a second layer of
another color is poured over the first layer so that it also forms a
thin layer of even color. This second layer should be even thinner than
the first. A layer one-sixteenth of an inch is a good dimension to plan
on, though these dimensions need not be accurately adhered to. If the
first layer is permitted to dry too long before the second layer is
added the result will be that as the finished sgraffito tile is drying
it will split in layers, the split coming between the layers of colors
that were permitted to dry too long.
A THIRD LAYER OF COLOR may be added over the second layer if the design
being planned calls for three divisions of colors. These layers are to
respond to the next step in the process, which is to expose portions of
each layer by tooling the surfaces so as to produce different colors at
the same time that the different depths are produced.
THE TOP LAYER WILL DRY WITH A SMOOTH SURFACE which will produce a
sgraffito tile with a glazed or partly polished surface while the other
layers will have a surface with dull texture.
TO PRODUCE A TILE WITH A DULL SURFACE throughout, the pouring stages
should be reversed in their steps. That is, the color that is to be the
top surface should be poured first and the other colors in their proper
relation, the last layer being the cement and sand or other concrete
mixture. This will result in the layer first poured in coming next to
the glass, having a dull finish when it is released from the mold.
TO PRODUCE THE SGRAFFITO DESIGN on the sgraffito tile, the tile should
be permitted to dry for about ten to twelve hours or if it remains
overnight the surface will be about right to work upon. The paper with
the design is then placed and retained in the correct position on the
cement tile and a dull pencil is used to trace the pattern, without the
use of carbon paper or other transfer medium. This will result in an
indented or embossed guide line on the cement surface of the tile which
can be used in scratching away through the first layer to the under
color.
THE TOP LAYER OF COLOR should be used to tell the main part of the
design story. If the subject is to be that of a bird or a ship, the top
layer design should be the bird or ship or other motif and the motif
should be so designed as to reach the boundaries of the tile surface so
as to produce a strengthening border arrangement all around the edge.
THE SECOND COLOR LAYER can then play a secondary part in both the color
scheme and the design arrangement, giving with its color placing a
contrast to the upper main layer used for the design.
THE BACKGROUND COLOR should be brilliant or dull depending upon the
surface color. If the surface color is brilliant, the bottom color
should be duller. If the upper color is dull, the background color can
then be the bright intenser color.
WHERE THREE LAYERS OF COLOR ARE USED the middle layer can be a color
harmonizing with both the background layer and the top layer and can be
used either for a pattern part to the design or it may be used simply as
a blending strata or layer appearing in the cut sides of the sgraffito
work.
COLOR HARMONY is essential in producing sgraffito color cement and a
color sketch will be a good safe preliminary in doing sgraffito work as
false steps or errors cannot be remedied in sgraffito and each step
should be carefully thought out before the tooling commences.
TO DO THE TOOLING, a scratch point should be used for incising or
scraping down along the line of the portion to be scraped out. The
portion within this boundary should then be scraped out down to the next
layer of color, care being taken not to gouge or cut deeply into the
under color. If the design is one of three layers, the center layer can
be included in the scraping out if the bottom color or layer is to
appear in that portion of the design. Do not attempt in the scraping to
take out large portions at a time as it will result in the breaking out
of sections that are wanted as part of the remaining design. It will be
found that the layers of color as scratched into retain their separate
layers and that the thin layer of the upper color separates easily from
the layer on which it rests. If a slight portion of the upper color is
inclined to remain attached to the background color or under layer let
it remain as it will give an interesting color quality and harmonize the
two colors.
THE SIDES OF THE SGRAFFITO LAYERS should gradually slope outward, and
after the layers have been tooled clear the sides of the layers should
be gone over and evened up in slant as well as in general finish. If the
corners are to be sharp or rounded in finish, see that the treatment is
carried out similarly in all parts so that a general unity of finish
will remain.
THE LAST STEP IN FINISH is to place the sgraffito tile in water so that
it is entirely immersed, and it is left in the water for several days
after which it is dried by being placed flat in a cool but not draughty
place to dry.
TO PRODUCE SGRAFFITO SURFACE on bowls or other round surfaces the layers
are produced by rotating the bowl in colors or spraying the colors on
with a sprayer such as is described in the chapter on coloring of bowls
and vases. The color can also be placed on with a brush if it is mixed
to the right consistency and the successive layers put on at the right
intervals.
SGRAFFITO FOR ARCHITECTURAL WORK holds great possibilities, and is being
gradually recognized by those builders who desire the charm of hand
wrought enrichment that graces so many of the Old World buildings.
Sgraffito decorative pillars and panels for buildings, homes and courts
is an assured possibility by the use of color cement and can be produced
with less cost than by the fired clay method as well as in larger, more
unified sections in that there are no kiln limitations to be considered
in doing the color cement. A plate is shown illustrating the use of
sgraffito in the making of an entrance to a college building designed in
the Italian Renaissance style and the sgraffito and ornamentation being
of Italian source, both combined in perfect harmony with the building as
a whole.
SGRAFFITO CAN BE APPLIED TO MANY FORMS such as book ends, fern boxes,
garden bowls, the requirement for success being mainly the placing of
the successive layers of color on each other when neither too dry or too
wet, and the scraping away of those parts desired when the cement is in
the proper condition.
[Illustration: Sgraffito Tile and Sgraffito in Architecture]
[Illustration]