Fixing a Problem – General Advice
• Paint more china paint on
top of it and re-fire.
• You can also remove color
with “Gold Off” (an acid-etching paste).
• You can also re-decal on
top of the problem decal with an identical decal. (This usually doesn’t work
out very well. You will still see the problem area)
• You can re-work the
decoration using another technique like Layering or All-Over (see the Gallery)
Firing Problems
(Mounting Problems are
treated last. See below.)
Color appears washed out or
not as strong as on prior firings
> Too Bad!
> Fire a Cone cooler the
next time you use that decal
> Make sure you were not
using a glass decal
> Possibly put an identical
decal overtop and re-fire
‘HaIo' Effect
After firing, there appears
to be a slight shadow around the edge of the decal which corresponds to where
the covercoat ended
> Fire a Cone hotter,or,
> Sand off the halo with
scouring powder or 280 mesh sandpaper
> Use distilled water in
the future
> Always wipe down your
ware with clean water before mounting
> Slow fire in the future
(this is the best solution)
[Question: “But, sir? Aren’t
iron and minerals inorganic? How can something inorganic burn away, sir?” Good
question, Private! The inorganic compounds found in tap water are not “fluxed”
like the inorganic compounds used in China Paints. (A Flux is anything that is
used to soften the glaze so that the color will melt into it. Most fluxes in
decals are powdered glass.) Because the inorganic compounds in tap water are
unfluxed, they volatilize away during the firing, unless there is a heavy
concentration of them in the water.]
Colors don’t look shinny or does not have a smooth feel
Remedy
> Fire a Cone hotter
> Fire slower
Design feels a little like
sandpaper after firing
> Vacuum kiln regularly
> Fire a Cone cooler the
next time you use that particular glaze
> Take some 280 mesh
sandpaper or scouring powder, and lightly sand down the roughness (stop if
glaze begins to scratch)
Also, just for good housekeeping,
run a vacuum attachment around the inside of your kiln on a regular basis. Fire
brick deteriorates, kiln wash gets crushed to powder, bisque sometimes has a
powdery residue (called ‘slurry) if not sponged down after cleaning the
greenware. Whatever. Your kiln gets dirty, and this kind of dust won’t fire
away but will float around in your kiln and sometimes attach to your pieces. So
vacuum your kiln once In a while.
As for sanding down the
roughness, china painters do this all the time, but they are sanding on a
harder porcelain finish. Test your hobby ceramics to see how easily the glaze
will scratch. Discontinue if it appears that it will scratch too easily.
A portion of the design
chips off or flakes off, like an egg shell off a hard boiled egg, only thinner
> Contact the company
that sold you the decal
Now you’d think that this
would happen more often since sometimes greenware can have hard spots (aka. Hot
Spots) in different places which also makes the glaze somewhat harder in those
areas. But this rarely happens to the extent that it affects the decal firing,
so don’t worry about it. Just know that if you are ever privileged to actually
see a fired decal that chips off, it is because the decal didn’t match the
expansion and contraction of the glaze it was being fired on.
FYI: Sharp fractures (ie.
chips that look like broken Christmas tree ornaments) occurred during the cool
down period; whereas shattered, but still attached to the piece, happened
during the heat-up. (It will look like you put the decal on a Krackle Glaze.)
A specific color of a
design that pulls back or frizzles a lot (aka. ‘Roll-up’)
> Contact the company
that supplied you with the decal
Note, decal colors don’t ‘go
bad’, any more than china paints go bad. This is because that they are
inorganic (which basically means ground-up minerals, metals, and glass). If a decal
is ‘bad’, it was bad from the beginning.
In lower quality decals, the
colors sometimes get contaminated before or during the printing process from
organic and inorganic dust particles floating around the printing room. With
better companies, the press room is environmentally controlled for temperature
and humidity, and is very clean.
When carbon (organic dust
particles) becomes imbedded or mixed in with (contaminates) a color, the result
is slight frizzling in that one color (since almost all ceramic decal printers
print only one color per day to allow sufficient drying time between colors).
Now non-color specific
Roll-up can occur in two other cases.
First, if the edges of the
decal haven’t been squeegeed down well. This seldom happens EXCEPT when a deal
has been peeled up to be relocated or has to be peeled up to have foreign
matter removed from underneath. Then it often happens that the decal doesn’t
want to go back down like it was before. If this happens to you, just remove
the decal completely, rub it around on the slick side of the wetted paper it
came off of, and re-apply it. What you have done is picked up some more of the
glue from the paper and transferred it to the decal, so that it will stick to
the ware. Newsflash: Without that glue your decal will never stick to the piece
(which is essential for it to fire correctly).
Second, if the piece has
grease of oil on it, this will sometimes manifest itself in crawling colors.
Oil (and grease) react differently to the presence of water than do other
impurities. They repel and encapsulate it, making it take longer to dry.
Moreover, even when once dry, grease and oil are no friend to ceramic color.
When your kiln is firing, they must burn-off as well. And when they do, the
color that was on top crawls. But that won’t happen to you, right? We assume
that you are cleaning you ware like a good little scout, yes?
> Place on the same shelf
in the kiln when firing
> Promote air circulation
in the kiln
> Slow fire
> Make sure that the
decals are from the same company
Your kiln, especially if it
is a big one, can have up to a two Cone temperature difference between the top
and the bottom when firing decals or gold (the top is hotter, the bottom is
cooler).
When you set 2 pieces that
have been decorated with the same decal on different shelves in the kiln, you
are firing them at different temperatures whether you like it or not. Normally
this is not a problem, except if you have one of those fickle families of
colors mentioned above. Then your decals will look different depending on where
you set them in the kiln.
Ideas for creating uniform
temperature:
• The best one (and most
expensive one) is to get a Down-draft Kiln Vent. They’re great! They almost
single-handedly make the temperature uniform from top to bottom, and, provide
much needed air circulation for covercoat bum-off, fume removal, and color
maturity.
• Plan B is to: 1) Keep your
peep holes open during the entire firing cycle; 2) Put decal pieces on the same
shelf, and; 3) Raise and lower the temperature slowly.
Re: Decals from different
companies - There are more than a few “copies”
of other companies’ decals floating
around the market place. In the Industry, we call them “knock-offs”. To the
uninitiated, they look the same, but a closer examination will show that they
are not. Always use the same company’s decals when using a particular design.
This is a good way to avoid unpleasant surprises.
(And lastly, lest we forget,
be sure that all the heating elements in the kiln are working properly, and,
don’t over pack your kiln with pieces to be fired.)
Pinholes
Spot(s) that fire away,
leaving a hole in the design.
> Always wipe down your
ware with clean water before mounting
> Squeegee thoroughly
Also, if too much dust has
settled on the piece before mounting, this dust tends to get under the decal,
and prevents the color from being in direct contact with the piece. By wiping
down the piece with clean water, you eliminate most of the dust, plus you leave
a thin film of water on the ware which makes the decal easier to slide around
and position when you are mounting it.
When squeegeeing, you start
lightly from the center of the decal, stroking outwards towards the edge. As
the decal becomes more firmly mounted, you stroke harder. This removes residual
water and bubbles. A ‘Decal Squeegee’ is very handy for doing this, but you may
also use a silk sponge, or a Kleenex, or a paper towel to squeegee with. (One
person I know swears by cloth baby diapers... unsoiled, of course.) Just make
sure that you have squeegeed very thoroughly, taking time to examine the decal
in the light to check for air/water bubbles.
Tiny depressions all over
the piece, not just the decal
> Properly fired bisque
> Follow manufacture’s
instructions for firing the glaze
> Toss the piece
Large sections of the decal
that fire away (aka. ‘Blow-outs’)
> Always Squeegee
thoroughly
> Allow 24 hours to dry
before firing
This is why you should
squeegee progressively harder as the decal becomes more firmly mounted. You
will even see the residual water that is being pulled out from under the decal
as you continue to squeegee. This is also why manufacturers recommend a 12 to
24 hour drying period before firing. This allows for even more water to
evaporate, and so, provide insurance for a decal that might not have been
tightly mounted.
By the way, this is why you
can’t mount decals on ‘Krackle Glazes’ (unless you surface prep with a product
like Apt-Il), because the water soaks through the cracks and is impossible to
get out from under the decal except by a lengthy drying period (days and days).
When fired, that water turns to steam and blows out the decal.
A large area of the design
that is rough and ‘etchy'
> Always Squeegee
thoroughly
> Allow 24 hours to dry
before firing
Now I’ll also mention ‘Fast
Firing’. When you burn off a covercoat too quickly (say, in an hour or less),
especially with a recently mounted decal, you invite trouble, usually in the
form of frizzling. Carbon burn-off takes time. Carbon can even hang around in a
poor ventilated kiln and re-attach to the covercoat as it is softening and
burning off. Don’t be in such a hurry. (Unless you are firing glass decals,
then be in a hurry. But also make sure that your glass pieces have had plenty
of time to dry. 24 hours minimum.)
Colors appear dirty, as if
they came out of a bad dishwasher
> Re-fire at a hotter
Cone
> ‘wring out’ your kiln
A crack in the design that
goes right down to the glaze
> Aw, Shucks!
- Brown decals that are
supposed to fire pink, but stay brown
- Reds that are supposed to
fire bright red, but come out dull or dark
> Fire a Cone hotter (for
brighter pinks)
> Promote air circulation
in your kiln (for brighter reds)
> A ‘brown’ pink didn’t
get enough heat to turn pink.
> A dull or dark red was
starved for oxygen.
With reds it is a question
of air, not heat. Reds like air. The more fresh air that a red gets, the better
it likes it. (This is also true for red glazes too.) Want a bright red? Set
your piece about 2” from an open peep hole and it will be the brightest red it
can be. Actually, many colors need air to mature properly. This is why leaving
those peep holes open for the complete firing cycle is advised. (For glazes
too.) PS- Don’t over pack your kiln either. This inhibits air circulation and
heat distribution.
Self explanatory
> Good News! Just re-fire
the ware at the proper Cone
Recommended Cones:
• Hobby Ceramics and Terra
Cotta: Cone 018 to 016
•
And here’s where it gets
tricky. There’s no one “all-purpose” one for hobby ceramics. Decal
manufacturers recommend a ‘range of temperatures’, not a specific Cone. This is
because some people want a shinny, glassy finIsh, (and so fire hotter), while
others want more depth (and so fire at the normal temperatures).
The two exceptions are In-glaze
Decals and Glass Decals. In-glaze decals were meant to be fired at Cone 06 or
hotter. (Don’t worry. In-glaze Decals are not generally available to the
public.) An underfired In-glaze Decal is rough to the touch, though it doesn’t
scratch off. This is because it is made from underglazes, and so must be
brought up the glaze firing temperatures before it will melt into the glaze. A Glass Decal was meant to fire and fuse at
Cone 022. If fired hotter, it fades significantly (sometimes almost
disappearing). And, of course, there’s always the possibility of mistaking a
non-firing decal for a ceramic decal (which disappears when fired).
A squiggly line or
peculiarly shaped pinhole
> Wipe down your piece
with clean water before mounting decal
> Keep your decal water
fairly clean
Odd Spots> Foreign matter got under the decal
during mounting.
I recommend changing your
decal water every so often, and, if you see a particle floating around on top
of the water, pick it out. I also recommend that you trim around your decal
with a pair of scissors before you soak it in the water, maybe ¼’ from the edge
of the covercoat. This will help prevent loose scrapes from neighboring decals (that
were on the same sheet of decal paper) from being put in the water and floating
off the paper to cause you trouble later.
Mounting Problems
The wax paper, which
frequently comes with a decal to protect it, does not want to separate easily,
but instead, sticks to the decal
> The Reverse Curl’ (see
below)
1) Turn the decal face down
on a flat surface.
2) Holding the wax paper
against the flat surface with one hand, curl back the decal with the other
hand. Go slow.

This works amazingly well.
If any traces of wax paper remain on the decal, just moisten your fingertip and
scratch them off with your fingernail.
As described
> Try warmer water
> Scratch the ‘hot spots’
on the back
> Throw away decal
For the most part, these
decals are no good anymore. But for diehards like me, there are still a couple
things that can be tried.
- Use warmer water. This
sometimes softens the wax and allows the water to pass thru.
• Turn the decal over and
scratch the white spots with your fingernail.
What you are doing is
massaging the water into and thru the hot spot. Often the decal will finally
release, but instead of sliding it oft the paper, you’ll have to peel it off
(don’t reverse It by accident).
Hot Spots are the #1 cause
of ruined decals bought at the ceramic shows. Unsuspecting people buy their
decals, take them out to the car, throw them in the back seat... on a sunny
day... and guess what? So keep those decals in the shade when traveling.
When ready to mount, decal
wants to pull apart and crack
> Toss decal
> Try very warm water
Commercial decorators sometimes
use products like Butyl-Cellosolve
(Ethylene glycol monobutyl
ether) in a 1% to 3% water solution. But this is because they want to reclaim a
brittle decal, not because they want a short cut to easier deal decorating. In
fact, it takes longer when products like this are used because you must let the
decal dry longer to allow the chemical to thoroughly evaporate out. Moreover,
Butyl Cellosolve is a toxic chemical to which prolonged exposure can result in
liver and kidney damage, anemia, and behavior problems (altho it is not nearly
so dangerous once mixed with water). Bottom line, it Is a good rescue solution,
but not a good production solution.
In days past, you could buy
liquid covercoat and spread it on top of a brittle decal to save it. Frankly, I
haven’t kept up with who still has this for sale.
Decal breaks apart when put
in water
> Contact company that
sold you the decal
This seldom happens in the
better decal companies, because each sheet is inspected after each pass through
the press. Renegade sheets are usually caught and so never make it to the
public or the commercial decorator.
Sometimes a company gets
cheap and uses a finer mesh screen to print the covercoat with. This leaves a
thinner deposit, and so uses less covercoat. It may lower the price of the decal,
but it makes them harder to work with. A decal with a little ‘body’ is
generally to be preferred.
As described
> Peel the decal off the
ware, rub it around on the slick side of the paper it came off of, and remount.
Now there are two other ways
to encounter this problem. The most common one is to re-position the decal too
much. I know that it's fun to slide a decal around on a piece to position it and
get it just right. But if you slide it too much, you won’t have enough glue
left to make it stick Then you’ll have to peel it off again and so on.
The other less common
circumstance is that a decal manufacturer used a cheaper paper to print on
which didn’t have much gum to begin with. (Decal paper is basically a water
absorbent paper with a coating of dried gum on one side.) This is rare with
European decals, but some American and oriental decals do use cheaper paper.
Cheap paper doesn’t mean they won’t work, it just means you can’t play with
them as much.
As described
> Warm water
> Possibly warm the piece
to be decorated
> Make cuts with a razor
blade (as a last resort)
In fact, the warmer the
water, the more pliable the decal (altho after 135°F, the decal tends to stretch
too much and distort). This same principle is behind warming the piece before
it is to be decorated. It keeps the warmed decal warm, and so stays easier to
stretch. Also, a judicious slice with a razor blade can often be just what the
doctor ordered. When I go to decal, the three things I always have ready are
warm water, a razor blade, and a squeegee.