Separation Enamel - Old and New Variations
by Tom Ellis
from Volume 11, No. 2, April 1992
has been an accessory enameling product for many years.
Traditionally it has been placed alongside of techniques that
some will label "hobby techniques" such as scrolling,
the use of lumps and threads, and "happy
accidents". It has been considered a high fire
technique with little control of the outcome. Objects made
from the separation technique have most often been limited to
forms with sloped sides or bowls. For many years, Thomas
C. Thompson Co. sold lead bearing separation enamel. If
this product was not properly thinned with oil, a black residue
would result after firing. It also did not seem to work
well on flat surfaces. Several years ago, Ceramic Coating
Company developed a lead free separation enamel. This is
now the separation enamel that Thompson Enamel carries.
The lead free separation enamel has several advantages over the
lead bearing separation - the absence of lead, the availability
of the product in dry powder, as well as oil base, no residue
after firing, and the ability to work on flat surfaces.
The physical principle that separation
enamel is based on is viscosity (see Enamel Potpourri in this
issue for more in-depth information). When separation
enamel is fired onto an enamel surface, a depression or
indentation develops where the separation was applied.
When two or more parallel lines of separation are fired into a
transparent enamel, the areas in between the lines become more
intense in color and the indented areas less intense in
color. When parallel lines are fired onto 2 or 3 layers of
enamel, trace amounts of each color layer become visible.
By varying elements to the process such as color choice,
combining opaque and transparent layers, placement of enamels,
placement of separation, firing times and temperature and enamel
thickness, many different results are possible. With
experimentation and consideration of the above elements,
separation enamel becomes very controllable and offers much
potential as an enameling technique.
Counter Enamel Application
Whatever form is decided upon, a
substantial coat of enamel should be applied to the back side of
the piece. If several coats of enamel are planned for the
front side, an equal amount of enamel should be applied to the
back. Thin coats of enamel are preferable.
Options on Layering Enamels
Direct on Copper Transparent* -
A simple and effective use of separation is to apply it to a
transparent enamel that works well direct on copper, a single
coat of a "direct on copper transparent", fired, then
an application of separation enamel, fired until the transparent
Transparent Clear - Transparent clear
enamel (flux) used as a base can be covered with a coat of
transparent enamel and then separated. Another option is
to apply a light colored opaque for the second coat, and then
any transparent for the third coat before separating.
Transparent Color - A
transparent color can be substituted for the above use of a
transparent clear with different results.
Opaque - Opaque enamel can be
used as a base with a transparent applied as a second coat, then
Stencil - The second coat
application can be stenciled onto the base coat so that some
areas of the base coat become part of the design.
Stenciling the second coat is one means of controlling the
influence of the separated areas in relation to the overall
composition of the work. Use any transparent for the third
coat application, covering the whole piece, then separating.
Wet Inlay - One or more opaque
enamel colors may be applied onto the base coat in the wet inlay
method to develop a design or pattern leaving areas of the base
coat exposed. Again, use any transparent for the third
coat application, covering the whole piece, then
separating. After each firing, always stone the edges.
Preparation of Separation Enamel
Oil Base - Using a small spoon
or knife, take out a suitable amount from the jar and apply onto
a piece of glass. Using oil from the jar, thin the enamel
to a paintable consistency with a palette knife. Mix
Dry Powder - Klyr Fire or any
gum and a small amount of water mixed with a palette knife on
glass to a paintable consistency works well. The dry
powder can also be mixed with a variety of oils.
Application of Separation Enamel
Screening Methods - Separation
enamel is very finely ground so it is suitable for making a
screening paste which could be used in a variety of screening
Sgrafitto - Separation can be
applied over the whole surface of an area or piece and after
drying, the design can be sgrafittoed in.
Stencil - Gum can be applied to
the final coat of fired enamel and then a stencil is
adhered. Dry separation powder can be sifted through a 150
mesh screen onto the stencil for unique effects.
Painting Methods - By far, the
most versatile means of controlling the outcome of the
separation work. The separation enamel is applied with a
small brush. The painted lines should not be any wider
than 1/8". When painting lines, the consistency of
the application should be rich enough so that when dry, the
lines are a consistent opaque ochre color. Separ-ation is
most effective when the painted lines of the design are at least
1/4" from one another, running parallel (or concentric
circles, squares, etc.). The idea is that when two
parallel lines are fired, the enamel flow in between the lines
is part of the excitement of separation. Lines should not
be spaced too far apart. The lines should interplay with
one another. Figure 1, above, shows different separation line
patterns that work effectively.
If the stencil or wet inlay method of
applying underlying enamel is used (as mentioned above under
"Options for Layering Enamels") then the separation
lines applied should somehow relate with or extend the
underlying pattern or design of the stencil or wet packed areas.
Separation enamels should be fired at
1450°F for 2½ to 3½ minutes, depending on size of piece
(smaller pieces may take less time, larger pieces more
time). If working on steep sided forms, after firing the
separation the enamel may tend to flow toward the bottom of the
form. This can be reversed by firing the piece upside down
on the last firing.
On flat pieces the surface of the
enamel can actually be sculpted with separation enamel.
The separation should be fired at a slightly lower temperature,
1400° - 1450°F for 2-3 minutes.
Separation in Conjunction with other
Separation can be used effectively when
it is placed only in specific areas of a piece. Using the
stencil technique, some areas within the design could be
separated giving a visual texture to those areas and leaving the
other areas as solid color. Gold or silver foil could be
added to the solid colored areas for highlights. Another
approach is to use separation as a means to achieve a border
around bowls, plates or wall pieces, with interiors using other
enameling techniques. Underglaze black can be used under
any of the transparent bases used in separation to expand
If the applied separation is too heavy
or too much is applied in a given area, sometimes these areas
will become dull or matte looking a few days later. This
can be corrected by applying another coat of transparent enamel
over the area.
On the other hand, if an insufficient
amount is applied, or the underlying coats of enamel are applied
too heavily, the separation effect will not be very
apparent. In this case, apply the separation again and
When using steep sided forms for
separation, many times the back side will develop stilt
marks. After firing the separation enamel, stone down the
stilt marks until smooth. Also stone off any residue
enamel on the stilt arms. Apply another coat of counter
enamel and refire upside down.
Imagination and persistence are the
keys to having fun and success with separation enamel.
Some combinations of color may work out sensationally, while
others are disappointing. If using opaque enamels, the
light to medium colors work best. Transparent colors fired
over darker opaques tend to get lost. A good test to
figure out successful color combinations is to coat a square
piece of copper with stripes of different colors, then
fire. The second application is again stripes of different
colors, but applied perpendicular to the first set of
stripes. All colors should be written down on paper as to
their placement. Separation is then applied to each color
square. After firing, many possible color combinations are
Separation enamel can have a place
outside of the "hobby" category.
*Direct on copper transparents -
There are many transparent lead free enamels that fire
successfully direct on copper without using a clear base.
Some of my personal favorites are: 2210 ivory, 2115 Mars,
2170 VanDyke, 2220 Chartreuse, 2325 Gem, 2420 Sea, 2520 Aqua,
2530 Water, 2615 Periwinkle, 2625 Winter, 2650 Heron, 2680
Prussian, 2755 Concord, and 2820 Pink.