Llewellyn Kouba on tue 1 may 01
Is it possible to make my own overglaze colors from a single batch formul=
a
and then add colorants, stains, mason stains etc. or is it best to purcha=
se
some kind of commercial glazes to do the job? I am looking for something
to use over top a cone 9 glaze in the way of over glazing. Any particula=
r
brand, company or series numbers that you prefer?
Thanks in advance.
Llewellyn Kouba
scott lykens on tue 1 may 01
Take your favorite clear or white glaze. Then add say 10% of some stain=
=2E
Mason has a catalog tells you temp, what chemicals not to use em with, st=
uff
like good with zinc, not good, must contain calcium, stuff like that.
for years i have used a base white make 10 gallons pour off half into
2000gram batches. add 10% stain. some stains are refractory, i pinch in
frit, some are fluxy, i pinch in epk, If you want reproducable results =
you
should think about doing it dry or guaging specific gravity.
And i cnat say this one enough, re-tare your triple beam between every
wieght.
>Is it possible to make my own overglaze colors from a single batch formu=
la
>and then add colorants, stains, mason stains etc. or is it best to purch=
ase
>some kind of commercial glazes to do the job? I am looking for somethin=
g
>to use over top a cone 9 glaze in the way of over glazing. Any particul=
ar
>brand, company or series numbers that you prefer?
>
>Thanks in advance.
>
>Llewellyn Kouba
>
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MJ on tue 13 apr 10
I am a novice potter. I recently bought some overglazes from Axner and the
instructions say to fire to cone 05. I tried this on pieces that had
previously been fired to cone 5 and a piece previously fired to cone 10.
The cone 5 pieces completely changed color from the original firing. The
cone 10 piece remained unchanged except for the underglaze. the cone 5
pieces also developed pinholes. The overglazes themselves seemed to work
fine.
Has anyone done a lot of testing on this and do cone 5 glazes normally
change color if fired to cone 05? I guess I thought they would be
unaffected because the firing was so much lower than the original. Any hel=
p
is appreciated. Thx, MJ
Lynn Goodman Porcelain Pottery on tue 13 apr 10
Hi MJ,
Without the recipe it is difficult to say for sure what is going on,
but I can hazard a guess: The ^5 glaze probably has some wide-range
fluxes (which help the glaze to melt) in it, like gerstley borate or
some frits; the glaze is probably starting to re-melt at ^05. The ^10
glaze is less likely to have those wide-range fluxes, so is less
likely to start
re-melting at ^05.
If you can give us the recipe for the glaze we can probably pinpoint
the problem. If it's a commercial glaze, and you still want to use the
overglazes, you may need to try other glazes.
Lynn
On Apr 13, 2010, at 12:30 PM, MJ wrote:
> I am a novice potter. I recently bought some overglazes from Axner
> and the
> instructions say to fire to cone 05. I tried this on pieces that had
> previously been fired to cone 5 and a piece previously fired to cone
> 10.
> The cone 5 pieces completely changed color from the original
> firing. The
> cone 10 piece remained unchanged except for the underglaze. the
> cone 5
> pieces also developed pinholes. The overglazes themselves seemed to
> work
> fine.
Lynn Goodman
Fine Porcelain Pottery
Cell 347-526-9805
www.lynngoodmanporcelain.com
Snail Scott on wed 14 apr 10
On Apr 13, 2010, at 11:30 AM, MJ wrote:
> I am a novice potter. I recently bought some overglazes from Axner
> and the
> instructions say to fire to cone 05. I tried this on pieces that had
> previously been fired to cone 5 and a piece previously fired to cone
> 10.
> The cone 5 pieces completely changed color from the original firing...
This is quite common, actually. Refiring to a lower
temperature has an effect similar to doing a long
hold midway through the cooling phase of the original
firing. For some glazes, the change (whether from a
long cooling hold or refiring lower) is negligible, but
for others, especially true matte glazes, the change
can be huge.
This won't happen with every glaze, but clearly your
glazes are the sort for which it matters. If you really
want to refire to ^05 using these products, you may
need to change your base glaze. If you want to keep
your base glaze, you may need to give up refiring to
^05.
-Snail.
marci and rex on wed 14 apr 10
At 10:42 AM 4/14/2010, Snail Scott wrote:
>On Apr 13, 2010, at 11:30 AM, MJ wrote:
>
>>I am a novice potter. I recently bought some overglazes from Axner
>>and the
>>instructions say to fire to cone 05. I tried this on pieces that had
>>previously been fired to cone 5 and a piece previously fired to cone
>>10.
>>The cone 5 pieces completely changed color from the original firing...
In relation to this : I would be interested
in doing tests on various glazes and clays... If any of you
guys would be willing to send me small test tiles (
or broken shards ) of different glazes and clays, labeled
with what they are , I d be glad to test fire
them wit different overglazes: Chinapaints ( several colors)
, lusters, Liquid bright gold. etc ... and Id photograph and post
the results for everyone to see...
So , anyone who would be willing to be part of
this, please email me...
Im leaving in the morning for a show in Indiana but will be back
saturday night .. ( or you can email to my yahoo traveling address
chinapaintgirl2@yahoo.com
Marci the chinapainter
Johanna DeMaine on thu 15 apr 10
I have experienced a very similar thing happening when I have been testin=
=3D
g
to find the softening point of glazes for adhering laser decals which are=
=3D
only unfluxed iron oxide printed onto decal paper. My observations have
been that when you refire to the lower end of the softening range and the=
=3D
n
shut the kiln down you are left with a partially melted glaze which traps=
=3D
in
normal pinholes and bubbles that happen during glaze maturing. However i=
=3D
f
you can raise the temperature of the refire there is a point that the gla=
=3D
ze
totally smooths over even though you are not going to the top temperature=
=3D
of
the glaze. Each glaze varies. My investigations were on full gloss gla=
=3D
zes
fired to cone 10.
In your case, you can't alter the your refiring temperature as you are
governed by the proprietory cone 05 overglazes that you using so, as Snai=
=3D
l
suggested, you have to change your glaze.
Another option is to work with traditional Overglaze enamels which fire
between cone 017 and 014. There is no problem here with softening points=
=3D
and refreezing the glaze as the enamels have their own flux which adheres=
=3D
them to the glazed surface. Glazes which mature above approx Cone 03 don'=
=3D
t
seem to soften in the cone 017 and 014 range in my experience.
Johanna DeMaine
http://johanna.demaine.org
http://overglaze.info
MJ on thu 22 apr 10
Thanks so much for all of the information. Most of the overglazes I have
seen that fire to cone 017 and 014 seem to carry warnings about food
safety. I just found an Amaco overglaze set that says that indicates that
the overglaze itself is foodsafe, but that you should test the overall
effect for foodsafe. Using comercial glazes and overglazes, is there a
foodsafe overglaze that will work at 014-017? thanks again. MJ
On Wed, Apr 14, 2010 at 10:56 PM, Johanna DeMaine wrot=
e:
> I have experienced a very similar thing happening when I have been testin=
g
> to find the softening point of glazes for adhering laser decals which are
> only unfluxed iron oxide printed onto decal paper. My observations have
> been that when you refire to the lower end of the softening range and the=
n
> shut the kiln down you are left with a partially melted glaze which traps
> in
> normal pinholes and bubbles that happen during glaze maturing. However i=
f
> you can raise the temperature of the refire there is a point that the gla=
ze
> totally smooths over even though you are not going to the top temperature
> of
> the glaze. Each glaze varies. My investigations were on full gloss
> glazes
> fired to cone 10.
>
> In your case, you can't alter the your refiring temperature as you are
> governed by the proprietory cone 05 overglazes that you using so, as Snai=
l
> suggested, you have to change your glaze.
>
> Another option is to work with traditional Overglaze enamels which fire
> between cone 017 and 014. There is no problem here with softening points
> and refreezing the glaze as the enamels have their own flux which adheres
> them to the glazed surface. Glazes which mature above approx Cone 03 don'=
t
> seem to soften in the cone 017 and 014 range in my experience.
>
> Johanna DeMaine
> http://johanna.demaine.org
> http://overglaze.info
>
Johanna DeMaine on sun 25 apr 10
I am not familiar with commercial glazes as I make my own so I know their=
=3D
makeup. As for the Amaco Overglaze set it states that they are lead free=
=3D
and also state "Do Not use overglaze decorating colors on dinnerware
surfaces unless it is pre-tested for lead release" They might be referrin=
=3D
g
here to using it on commercial dinnerware. So if you use a lead free glaz=
=3D
e
with with no added colour together these Overglazes then I would believe
that your work would be food safe. However be aware they have only been
fired to Cone 017-014 and over time will abrade like any other soft glaze=
=3D
.
Johanna DeMaine
http://johanna.demaine.org
http://overglaze.info
marci and rex on sun 25 apr 10
At 02:39 AM 4/25/2010, Johanna DeMaine wrote:
>I am not familiar with commercial glazes as I make my own so I know their
>makeup. As for the Amaco Overglaze set it states that they are lead free
>and also state "Do Not use overglaze decorating colors on dinnerware
>surfaces unless it is pre-tested for lead release" They might be referring
>here to using it on commercial dinnerware. So if you use a lead free glaze
>with with no added colour together these Overglazes then I would believe
>that your work would be food safe. However be aware they have only been
>fired to Cone 017-014 and over time will abrade like any other soft glaze.
HI Johanna,
I havent used the Amaco overglazes but it would appear
that they are just chinapaints premixed with a waterbased drying
medium and sold for a bunch of money in a cute little tin ...
As for " lead free" , Im hoping Paul Lewing will jump in on
this.. but when he was testing for his book , he discovered
that even paints labeled lead free had some lead in them ... but
also, unless they are using some magical substance , it seems to
me ( not knowing the secrets of Mikasa etc ) that ALL of
the commercial dinnerware manufacturers are using chinapaints on
their silk screened decals applied to ALL dinnerware... the
difference being that if you have a chinapainter firing at home,
there is no way for them to consistently test their pieces to
make sure they are properly fired , whereas a big outfit like
Mikasa or any of the dinnerware manufacturers not only
have consistent , stable firing but are able to test to
make sure that they are firing properly .. They also have a set
of placement rules they now follow for where the design
area can be ( a certain amount down from the lip on a cup or mug etc=
)
China paints fired properly ( cone 015 ( approximately 1480
F / 800 C or hotter ) shouldnt abrade any quicker
than commercial dinnerware ( although any metallic gold or
silver will since it doesnt bond with the surface in the same
way that the chinapaints do ) ..... I painted a set of mugs for
my dad in 1998 . He uses them every day and into the dishwasher
they go and they still look the same as when I painted them ... (
for better or worse LOL ) ..
Marci the chinapainter
Paul Lewing on sun 25 apr 10
On Apr 25, 2010, at 7:39 AM, marci and rex wrote:
I havent used the Amaco overglazes but it would appear
that they are just chinapaints premixed with a waterbased drying
medium and sold for a bunch of money in a cute little tin ...
As for " lead free" , Im hoping Paul Lewing will jump in on
this.. but when he was testing for his book , he discovered
that even paints labeled lead free had some lead in them ...
I had several colors of one brand of china paints tested and they did
have lead in them. However, it was not Amaco's overglaze colors. I
believe John Baymore had some of these tested once and they were
indeed lead free.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
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