Decals and Ceramics

Source: http://users.skynet.be/russel.fouts/Files/sources.txt

Short version of info from Denise’s handout:

Computer Decals for Ceramics info from Denise Pelletier
Almost any glazed object works, also fired burnished terra sigillata and
most vitreous slips. (Porous surfaces do not work. Terra-sigged pieces
should be fired to at least c/04). Every glaze is different, so students
should come with an attitude of testing and experimentation. Computer
decals work over varying firing ranges, so the first try is always an
experiment to find what temperature will work best with my given glaze.
It's a good idea to have some small glazed test pieces or tiles if you
want to experiment. You might also try decals on found glazed objects.
How and why do laser printer decals work


Black and white laser-printer toner is composed of tiny iron filings,
other pigments, and tiny beads of plastic. When a laser printer prints
an image, it establishes a static field on the piece of paper, the toner
sticks to the field, then the whole thing goes through a heat element
which melts the plastic bits, fixing the toner to the paper (in this
case, decal paper). When a decal from a printer containing enough iron
oxide is applied to a ceramic surface and fired, the iron oxide survives
the firing. The resulting image on the ceramic surface is permanent and
sepia-colored, ranging from tones of brown to reddish-purple or ochre.
The exact color depends on the composition of the glaze underneath the
decal, and the firing temperature of the decal.


Not all laser printer cartridges contain iron or enough iron to work as
a ceramic decal. All Apple black laser printers work, and so do Hewlett
Packard black laser printers. Other brands of laser printers may work,
but there is no guarantee unless you test them first. Bubble jet,
inkjet, and all color printers do NOT work because they don't contain
any or enough iron or other metallic oxides.


The printing goes on the SHINY side of the paper. Make sure you cut the
paper to a size that the printer is capable of. Many printers prefer an
8 1/2" x 11" piece of decal paper to be trimmed slightly B say, an
1/8"less on length and width. Test first and trim if needed. Same goes
for 11" x 14" printers.


Print your image on the decal paper! Print extras if a particular image
is important, because sometimes a decal might tear or nun when you apply
it, so it's best to have extras.


Transferring the decal to the ceramic surface


Apply the decals in the same way that you would apply a commercial or
silkscreen decal. However, you should keep in mind that computer decals
sometimes give you problems if the cover coat isn't right. If the cover
coat is too thin, the image will tear or break apart-if it's too thick
you may have trouble adhering it to your piece or incomplete adhesion
(resulting in burning off part of your image)            -


1. Clean the surface of your piece (where the decal will go) with
alcohol and a clean cloth.


2. Cut out your image as close to the edges as possible. Try to make
curved rather than angled comers and edges. Sharp edges can cause the
decal to lift up.


3. Fill a shallow bottomed pan or tray with warm water. Soak the decal
for 30-60 seconds, or until the cover coat and image begin to separate
from the paper. (Sometimes the paper will curl and flatten out again)


4. With a wet sponge moisten the ceramic surface where the decal will
go. This helps you position your decal without wrinkling or tearing it.


5. GENTLY slide the decal into position on your piece, carefully
smoothing it from the center outward, with a small sponge, soft rubber
rib, or rubber brayer. This forces all the water and air bubbles out
from beneath the decal. Check to make sure there are no air bubbles or
edges that won't stick. If the decal is not in complete contact with the
surface, it will disappear in the firing. If you need to reposition the
decal, flood it with a little water first.


6. Let the decal dry overnight.


Firing the decal


The firing temperature for computer decals is quite variable, and
depends on the glaze that the decal is on. Since every glaze is
different, you must experiment to know what the optimum firing
temperature will be for any given glaze. Success can be had from c/018
(maybe lower) all the way to c/9. Basically you should try to fire at
the temperature where the glaze is just beginning to flux. This melts
the iron into the glaze, preserving the image. If you fire too hot, the
glaze will suck up all of the iron or distort your image. If you fire
too low, the image will smudge or wipe off. These are some general
firing ranges:


On china paint: 4020 - c/018
On low-fire glaze: c/06 - c/010
On cone 6 glaze: c/04 - c/1
On cone 10 glaze: c/04 -c/6
On terra sigillata: fire at least to c/04, preferably a bit higher on
burnished sigillata only


***Make sure your decals are stacked in the kiln with at least 2" of
clearance between shelves. Fire slowly especially in the beginning to
allow cover coat to bum off without lifting the decal or causing
incomplete bumoff of cover coat. The lid or door of your kiln should be
cracked until the cover coat is completely burned off. I like to leave
the kiln cracked right through red heat


EXPERIMENT! You will need to find the temperature that is right for your
glaze. If your image burns out at a low temperature, your toner may not
have any or enough iron. Even if you've found a temperature that works
for a particular glaze, try firing hotter or cooler-sometimes a long
firing range will work and give you different colors or shades of iron.


ALSO: use what you know about glazes to help you... Clear glazes with
lots of gerstley borate or nepheline syenite tend to "eat" or distort
the image. Try firing the decal lower or bag that glaze! And remember,
if what you need is a consistent undistorted image, it is easier to
succeed with glazes c/6 or above.


BIBLIOGRAPHY for Computer Decals
Johnson, Garth, MFA Thesis, Technical Statement,  NYSCC, Alfred
University, 2000
Ross, Katherine, "Ceramic Decals from the Computer" (handout) School of
the Art Institute of Chicago
Scott, Paul  Ceramics and Print


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