Those darned bubbles!

EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40 minutes
hold time at 1270 degreess, but they still show up! I am getting rather
frustrated by it all. I can "repair" them by adding glaze to the holes (that
are more like inverted craters going all the way down to the clay) and
refiring once or even twice, but I have a very small kiln at home, and find
it both a waste of space and power, while at the same time not wanting to
"lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650, then up
to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy
being that over about 400, I don't even let the cool air of the laundry room
in, but after that, I take out a couple of plugs (top center and bottom) and
under 200 I start opening the lid of the kiln a little. That shouldn't
affect the bubbles, though, as I am sure they have set at much higher
temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

How high are you bisque firing to? What glaze is this happening with (is it
all glazes, just one, a mix)? We need to know more before suggestions would
be of much use. 40 minutes of hold time is way more than you should need so
something is not as it should be.


"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am getting
rather frustrated by it all. I can "repair" them by adding glaze to the
holes (that are more like inverted craters going all the way down to the
clay) and refiring once or even twice, but I have a very small kiln at
home, and find it both a waste of space and power, while at the same time
not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650, then
up to 1270 and hold for 30 minutes. The cooling was over almost a day.
Policy being that over about 400, I don't even let the cool air of the
laundry room in, but after that, I take out a couple of plugs (top center
and bottom) and under 200 I start opening the lid of the kiln a little.
That shouldn't affect the bubbles, though, as I am sure they have set at
much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

Hi DKat! Good to see you!

I am firing bisque to 1050 C.

It usually happens with the really glossy glazes, but I actually had one
bubble on a matte glaze this time as well.

Since the bubbles go all the way in to the clay, do you think I might be
bisque firing too low, so that there are "substances" left in the clay
before the glaze firing?

I do think my oven's thermometer might show a bit higher than it actually
is, so maybe just increasing to 1060 or 1070 would help?

Once again - any input greatly appreciated! Especially since I have a full
load for bisque firing ready.

Marianne



"DKat" wrote in message
...
How high are you bisque firing to? What glaze is this happening with (is
it all glazes, just one, a mix)? We need to know more before suggestions
would be of much use. 40 minutes of hold time is way more than you should
need so something is not as it should be.


"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am getting
rather frustrated by it all. I can "repair" them by adding glaze to the
holes (that are more like inverted craters going all the way down to the
clay) and refiring once or even twice, but I have a very small kiln at
home, and find it both a waste of space and power, while at the same time
not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650, then
up to 1270 and hold for 30 minutes. The cooling was over almost a day.
Policy being that over about 400, I don't even let the cool air of the
laundry room in, but after that, I take out a couple of plugs (top center
and bottom) and under 200 I start opening the lid of the kiln a little.
That shouldn't affect the bubbles, though, as I am sure they have set at
much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

Hi Marianne!

I'm home sick with flu and not functioning 100% so bare (or is that bear)
with me...

First, you should use cones on all firings or at least do regular spot
checks. You need to know what heat work you are getting not just what
temperature you are going to and you need to know that for different spots
of your kiln.

You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995 C)
and have no problems but I mix my own glazes and know the materials I am
working with. Firing to 04 is often recommended. Do you make up your own
glazes or are you buying glazes? If you don't fire with cones, see if you
can beg, borrow or steal some until you can buy your own, at least to check
your next bisque firing.

You can get bubbles before if your pot is very, very dry when glazing. I am
one of the few potters out on the eastcoast that I know of who rinses off
their bisqueware before glazing. It is a really, really quick rinse so the
pots are still absorbant. I was taught in the desert environment where it
was so dry you could soak your bisqueware in water and five minutes later
they would be bone dry. In fact you had to dip them in water or the glaze
bubbled up. You can wipe down your pots with a damp sponge to both clean
them off and decrease bubbling on the dry glaze surface. This is probably
not the problem with your glaze however. It is something you would notice
by now.

Let us know about the glazes you use. (if you mix your own, what
ingredients - better yet what recipe are you using).

"Bubbles_" wrote in message
...
Hi DKat! Good to see you!

I am firing bisque to 1050 C.

It usually happens with the really glossy glazes, but I actually had one
bubble on a matte glaze this time as well.

Since the bubbles go all the way in to the clay, do you think I might be
bisque firing too low, so that there are "substances" left in the clay
before the glaze firing?

I do think my oven's thermometer might show a bit higher than it actually
is, so maybe just increasing to 1060 or 1070 would help?

Once again - any input greatly appreciated! Especially since I have a full
load for bisque firing ready.

Marianne



"DKat" wrote in message
...
How high are you bisque firing to? What glaze is this happening with (is
it all glazes, just one, a mix)? We need to know more before suggestions
would be of much use. 40 minutes of hold time is way more than you
should need so something is not as it should be.


"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am getting
rather frustrated by it all. I can "repair" them by adding glaze to the
holes (that are more like inverted craters going all the way down to the
clay) and refiring once or even twice, but I have a very small kiln at
home, and find it both a waste of space and power, while at the same
time not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650,
then up to 1270 and hold for 30 minutes. The cooling was over almost a
day. Policy being that over about 400, I don't even let the cool air of
the laundry room in, but after that, I take out a couple of plugs (top
center and bottom) and under 200 I start opening the lid of the kiln a
little. That shouldn't affect the bubbles, though, as I am sure they
have set at much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

Hey again

Sorry you aren't feeling well! Get well soon!

I think it is "bear" - as in to bear a burden, not the animal - hehe!

Okay - I haven't even seen anyone using cones over here in Europe - my
teacher doesn't even with her new kiln, and neither did an old teacher of
mine. I can't remember seeing any in the extensive catalogue from my dealer,
either.

I was told that sponging off bisque-ware was only to remove the dust. My
workshop typically has a humidity of around 50 %. I guess maybe that should
be enough.

But, when you mention during glazing, I do sometimes se that just little
spots aren't covered - like a little speck of grog. I just dab it with my
brush with glaze on it, but could that be part of the problem? I like your
suggestion of a little quick dip in water, and will try that later on. I
need to get myself one of those potter's pencils that doesn't burn away -
and start numbering my pots and writing down their whole way through the
processes.

The clay I use is this:
http://www.michel.ch/michel/katalog/...?Redirect=True

Apollo Steinzeugton 1000 - 1300°C
weiss - hellcrème - hellgrau

Westerwälder Steinzeugton ( WM2502 ), sehr fein schamottiert

Hervorragender Drehton, sehr plastisch, gute Standfestigkeit, auch für sehr
grosse Stücke. Einfach und gut im Trocknen. Guter Glasurträger. Raku
möglich.

Technische Daten
Rohbrand 950 - 980°C
Brennbereich 1000 - 1300°C
Sintertemperatur 1220°C
Brennfarbe weiss - hellcrème - hellgrau
Schamottierung 25 % 0 - 0.2 mm
Trockenschwindung 5 %
1000°C 1100°C 1200°C 1260°C
Brennschwindung 0.5 % 3 % 5 %
Wasseraufnahme 14 % 9 % 3 %
WAK ( 20 - 500 °C ) 7.2

I'm stuck on translating any of this at the moment, but will try if you
don't get the general gist of it.

These are the glazes I use.
http://www.michel.ch/michel/katalog/...?Redirect=True

The one I have most problems with at the moment is 101 with a glaze improver
over. The improver - number 100 - makes it go different blues and greens and
blacks when I add it on top. Fantastic colors, but the bubbles keep showing
up. Mind you, I had a bubble on a matte glaze - 404, I think - on this last
high firing. I don't have this problem at all with low-fire stuff - at 1050
C, same as my bisques (that way I can mix them a bit and get a full kiln
faster).

My kiln is teeny - only about 2 feet wide and maybe 3 feet tall inside - so
I wouldn't expect huge temperature ranges inside except when firing with the
holes open - on in the lid, one right down at the bottom. possibly even
below the bottom shelf. I open those about up to 650 then close them. I
can't remember any bubbly piece specifically being by the open holes, and
glazes only really start to melt well above 650C, don't they?

I'm going to go fire my kiln now. It is a bisque, and I will check my glazes
to see if they can be fired higher than 1050 - there are a couple I have
that shouldn't be, which is why I have stayed at that temp, and I have some
glazed stuff going in now.

Thanks again for your time and input!

***virtual chicken soup for you to get better on***

Marianne


"DKat" wrote in message
...
Hi Marianne!

I'm home sick with flu and not functioning 100% so bare (or is that bear)
with me...

First, you should use cones on all firings or at least do regular spot
checks. You need to know what heat work you are getting not just what
temperature you are going to and you need to know that for different spots
of your kiln.

You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995 C)
and have no problems but I mix my own glazes and know the materials I am
working with. Firing to 04 is often recommended. Do you make up your own
glazes or are you buying glazes? If you don't fire with cones, see if you
can beg, borrow or steal some until you can buy your own, at least to
check your next bisque firing.

You can get bubbles before if your pot is very, very dry when glazing. I
am one of the few potters out on the eastcoast that I know of who rinses
off their bisqueware before glazing. It is a really, really quick rinse
so the pots are still absorbant. I was taught in the desert environment
where it was so dry you could soak your bisqueware in water and five
minutes later they would be bone dry. In fact you had to dip them in
water or the glaze bubbled up. You can wipe down your pots with a damp
sponge to both clean them off and decrease bubbling on the dry glaze
surface. This is probably not the problem with your glaze however. It is
something you would notice by now.

Let us know about the glazes you use. (if you mix your own, what
ingredients - better yet what recipe are you using).

"Bubbles_" wrote in message
...
Hi DKat! Good to see you!

I am firing bisque to 1050 C.

It usually happens with the really glossy glazes, but I actually had one
bubble on a matte glaze this time as well.

Since the bubbles go all the way in to the clay, do you think I might be
bisque firing too low, so that there are "substances" left in the clay
before the glaze firing?

I do think my oven's thermometer might show a bit higher than it actually
is, so maybe just increasing to 1060 or 1070 would help?

Once again - any input greatly appreciated! Especially since I have a
full load for bisque firing ready.

Marianne



"DKat" wrote in message
...
How high are you bisque firing to? What glaze is this happening with
(is it all glazes, just one, a mix)? We need to know more before
suggestions would be of much use. 40 minutes of hold time is way more
than you should need so something is not as it should be.


"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am
getting rather frustrated by it all. I can "repair" them by adding
glaze to the holes (that are more like inverted craters going all the
way down to the clay) and refiring once or even twice, but I have a
very small kiln at home, and find it both a waste of space and power,
while at the same time not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650,
then up to 1270 and hold for 30 minutes. The cooling was over almost a
day. Policy being that over about 400, I don't even let the cool air of
the laundry room in, but after that, I take out a couple of plugs (top
center and bottom) and under 200 I start opening the lid of the kiln a
little. That shouldn't affect the bubbles, though, as I am sure they
have set at much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

I'm assuming you are also posting on clayart where you might have more luck
of overlapping with someone using these glazes.

With that high of humidity don't dunk the pots (I only rinse mine under the
tap very, very quickly). Dunking them is going to empty the air out of them
and you don't want that. I would though, wipe them off with a damp sponge.

How are you venting your kiln? Clay and glaze materials put off some not
good stuff...

Since you are buying a commercial glaze material you should be able to call
them up and get some support. Since you don't know the ingredients and they
do it is their responsiblity to give you help on this. Generally people who
sell glazes are all to happy to do all they can to keep their customers
happy and buying their product.

IMO - There really isn't anything anyone else can do to help unless they are
familiar with the glaze or know what it is made up with. As I said a 40
minute soak is to me overkill.

Thanks for the chicken soup - it always works.

Donna

"Bubbles_" wrote in message
...
Hey again

Sorry you aren't feeling well! Get well soon!

I think it is "bear" - as in to bear a burden, not the animal - hehe!

Okay - I haven't even seen anyone using cones over here in Europe - my
teacher doesn't even with her new kiln, and neither did an old teacher of
mine. I can't remember seeing any in the extensive catalogue from my
dealer, either.

I was told that sponging off bisque-ware was only to remove the dust. My
workshop typically has a humidity of around 50 %. I guess maybe that
should be enough.

But, when you mention during glazing, I do sometimes se that just little
spots aren't covered - like a little speck of grog. I just dab it with my
brush with glaze on it, but could that be part of the problem? I like your
suggestion of a little quick dip in water, and will try that later on. I
need to get myself one of those potter's pencils that doesn't burn away -
and start numbering my pots and writing down their whole way through the
processes.

The clay I use is this:
http://www.michel.ch/michel/katalog/...?Redirect=True

Apollo Steinzeugton 1000 - 1300°C
weiss - hellcrème - hellgrau

Westerwälder Steinzeugton ( WM2502 ), sehr fein schamottiert

Hervorragender Drehton, sehr plastisch, gute Standfestigkeit, auch für
sehr grosse Stücke. Einfach und gut im Trocknen. Guter Glasurträger. Raku
möglich.

Technische Daten
Rohbrand 950 - 980°C
Brennbereich 1000 - 1300°C
Sintertemperatur 1220°C
Brennfarbe weiss - hellcrème - hellgrau
Schamottierung 25 % 0 - 0.2 mm
Trockenschwindung 5 %
1000°C 1100°C 1200°C 1260°C
Brennschwindung 0.5 % 3 % 5 %
Wasseraufnahme 14 % 9 % 3 %
WAK ( 20 - 500 °C ) 7.2

I'm stuck on translating any of this at the moment, but will try if you
don't get the general gist of it.

These are the glazes I use.
http://www.michel.ch/michel/katalog/...?Redirect=True

The one I have most problems with at the moment is 101 with a glaze
improver over. The improver - number 100 - makes it go different blues and
greens and blacks when I add it on top. Fantastic colors, but the bubbles
keep showing up. Mind you, I had a bubble on a matte glaze - 404, I
think - on this last high firing. I don't have this problem at all with
low-fire stuff - at 1050 C, same as my bisques (that way I can mix them a
bit and get a full kiln faster).

My kiln is teeny - only about 2 feet wide and maybe 3 feet tall inside -
so I wouldn't expect huge temperature ranges inside except when firing
with the holes open - on in the lid, one right down at the bottom.
possibly even below the bottom shelf. I open those about up to 650 then
close them. I can't remember any bubbly piece specifically being by the
open holes, and glazes only really start to melt well above 650C, don't
they?

I'm going to go fire my kiln now. It is a bisque, and I will check my
glazes to see if they can be fired higher than 1050 - there are a couple I
have that shouldn't be, which is why I have stayed at that temp, and I
have some glazed stuff going in now.

Thanks again for your time and input!

***virtual chicken soup for you to get better on***

Marianne


"DKat" wrote in message
...
Hi Marianne!

I'm home sick with flu and not functioning 100% so bare (or is that bear)
with me...

First, you should use cones on all firings or at least do regular spot
checks. You need to know what heat work you are getting not just what
temperature you are going to and you need to know that for different
spots of your kiln.

You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995 C)
and have no problems but I mix my own glazes and know the materials I am
working with. Firing to 04 is often recommended. Do you make up your
own glazes or are you buying glazes? If you don't fire with cones, see
if you can beg, borrow or steal some until you can buy your own, at least
to check your next bisque firing.

You can get bubbles before if your pot is very, very dry when glazing. I
am one of the few potters out on the eastcoast that I know of who rinses
off their bisqueware before glazing. It is a really, really quick rinse
so the pots are still absorbant. I was taught in the desert environment
where it was so dry you could soak your bisqueware in water and five
minutes later they would be bone dry. In fact you had to dip them in
water or the glaze bubbled up. You can wipe down your pots with a damp
sponge to both clean them off and decrease bubbling on the dry glaze
surface. This is probably not the problem with your glaze however. It
is something you would notice by now.

Let us know about the glazes you use. (if you mix your own, what
ingredients - better yet what recipe are you using).

"Bubbles_" wrote in message
...
Hi DKat! Good to see you!

I am firing bisque to 1050 C.

It usually happens with the really glossy glazes, but I actually had one
bubble on a matte glaze this time as well.

Since the bubbles go all the way in to the clay, do you think I might be
bisque firing too low, so that there are "substances" left in the clay
before the glaze firing?

I do think my oven's thermometer might show a bit higher than it
actually is, so maybe just increasing to 1060 or 1070 would help?

Once again - any input greatly appreciated! Especially since I have a
full load for bisque firing ready.

Marianne



"DKat" wrote in message
...
How high are you bisque firing to? What glaze is this happening with
(is it all glazes, just one, a mix)? We need to know more before
suggestions would be of much use. 40 minutes of hold time is way more
than you should need so something is not as it should be.


"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am
getting rather frustrated by it all. I can "repair" them by adding
glaze to the holes (that are more like inverted craters going all the
way down to the clay) and refiring once or even twice, but I have a
very small kiln at home, and find it both a waste of space and power,
while at the same time not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650,
then up to 1270 and hold for 30 minutes. The cooling was over almost a
day. Policy being that over about 400, I don't even let the cool air
of the laundry room in, but after that, I take out a couple of plugs
(top center and bottom) and under 200 I start opening the lid of the
kiln a little. That shouldn't affect the bubbles, though, as I am sure
they have set at much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

Hi! Hope you are feeling better today!

No, I don't post on clayart. Is that a newsgroup, or a forum? I don't like
forums, I keep forgetting to keep up and it ends up that I just drop it.

Hmmm - venting my kiln? Well - I told you about the holes. The kiln is in
the laundry room, so I make sure there are no clean clothes in the room and
then open the window. The room does get warmer, but not too bad.

All the glazes I use are so-called "poison class free" - ie. they are
supposed to contain no poisonous materials. Still, the room really stinks,
especially when I am glaze firing, of course, so I always close the door to
the hallway and have the window open in there.

There is a hitch with me trying to discuss this with the makers of the
glaze, because my German really isn't up to par to discuss this! I tried
talking about it with the boss where I buy the stuff, but even face-to-face,
I didn't understand everything he said, and it just got so complicated that
I gave up. I did catch a couple of ideas, but I thought the gang on here
could get into this in general, as it is happening on other glazes than the
101+100 combination, though that one is the worst.

Have a lovely day!

Marianne



"DKat" wrote in message
...
I'm assuming you are also posting on clayart where you might have more
luck of overlapping with someone using these glazes.

With that high of humidity don't dunk the pots (I only rinse mine under
the tap very, very quickly). Dunking them is going to empty the air out
of them and you don't want that. I would though, wipe them off with a
damp sponge.

How are you venting your kiln? Clay and glaze materials put off some not
good stuff...

Since you are buying a commercial glaze material you should be able to
call them up and get some support. Since you don't know the ingredients
and they do it is their responsiblity to give you help on this. Generally
people who sell glazes are all to happy to do all they can to keep their
customers happy and buying their product.

IMO - There really isn't anything anyone else can do to help unless they
are familiar with the glaze or know what it is made up with. As I said a
40 minute soak is to me overkill.

Thanks for the chicken soup - it always works.

Donna

"Bubbles_" wrote in message
...
Hey again

Sorry you aren't feeling well! Get well soon!

I think it is "bear" - as in to bear a burden, not the animal - hehe!

Okay - I haven't even seen anyone using cones over here in Europe - my
teacher doesn't even with her new kiln, and neither did an old teacher of
mine. I can't remember seeing any in the extensive catalogue from my
dealer, either.

I was told that sponging off bisque-ware was only to remove the dust. My
workshop typically has a humidity of around 50 %. I guess maybe that
should be enough.

But, when you mention during glazing, I do sometimes se that just little
spots aren't covered - like a little speck of grog. I just dab it with my
brush with glaze on it, but could that be part of the problem? I like
your suggestion of a little quick dip in water, and will try that later
on. I need to get myself one of those potter's pencils that doesn't burn
away - and start numbering my pots and writing down their whole way
through the processes.

The clay I use is this:
http://www.michel.ch/michel/katalog/...?Redirect=True

Apollo Steinzeugton 1000 - 1300°C
weiss - hellcrème - hellgrau

Westerwälder Steinzeugton ( WM2502 ), sehr fein schamottiert

Hervorragender Drehton, sehr plastisch, gute Standfestigkeit, auch für
sehr grosse Stücke. Einfach und gut im Trocknen. Guter Glasurträger. Raku
möglich.

Technische Daten
Rohbrand 950 - 980°C
Brennbereich 1000 - 1300°C
Sintertemperatur 1220°C
Brennfarbe weiss - hellcrème - hellgrau
Schamottierung 25 % 0 - 0.2 mm
Trockenschwindung 5 %
1000°C 1100°C 1200°C 1260°C
Brennschwindung 0.5 % 3 % 5 %
Wasseraufnahme 14 % 9 % 3 %
WAK ( 20 - 500 °C ) 7.2

I'm stuck on translating any of this at the moment, but will try if you
don't get the general gist of it.

These are the glazes I use.
http://www.michel.ch/michel/katalog/...?Redirect=True

The one I have most problems with at the moment is 101 with a glaze
improver over. The improver - number 100 - makes it go different blues
and greens and blacks when I add it on top. Fantastic colors, but the
bubbles keep showing up. Mind you, I had a bubble on a matte glaze - 404,
I think - on this last high firing. I don't have this problem at all with
low-fire stuff - at 1050 C, same as my bisques (that way I can mix them a
bit and get a full kiln faster).

My kiln is teeny - only about 2 feet wide and maybe 3 feet tall inside -
so I wouldn't expect huge temperature ranges inside except when firing
with the holes open - on in the lid, one right down at the bottom.
possibly even below the bottom shelf. I open those about up to 650 then
close them. I can't remember any bubbly piece specifically being by the
open holes, and glazes only really start to melt well above 650C, don't
they?

I'm going to go fire my kiln now. It is a bisque, and I will check my
glazes to see if they can be fired higher than 1050 - there are a couple
I have that shouldn't be, which is why I have stayed at that temp, and I
have some glazed stuff going in now.

Thanks again for your time and input!

***virtual chicken soup for you to get better on***

Marianne


"DKat" wrote in message
...
Hi Marianne!

I'm home sick with flu and not functioning 100% so bare (or is that
bear) with me...

First, you should use cones on all firings or at least do regular spot
checks. You need to know what heat work you are getting not just what
temperature you are going to and you need to know that for different
spots of your kiln.

You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995
C) and have no problems but I mix my own glazes and know the materials I
am working with. Firing to 04 is often recommended. Do you make up
your own glazes or are you buying glazes? If you don't fire with cones,
see if you can beg, borrow or steal some until you can buy your own, at
least to check your next bisque firing.

You can get bubbles before if your pot is very, very dry when glazing. I
am one of the few potters out on the eastcoast that I know of who rinses
off their bisqueware before glazing. It is a really, really quick rinse
so the pots are still absorbant. I was taught in the desert environment
where it was so dry you could soak your bisqueware in water and five
minutes later they would be bone dry. In fact you had to dip them in
water or the glaze bubbled up. You can wipe down your pots with a damp
sponge to both clean them off and decrease bubbling on the dry glaze
surface. This is probably not the problem with your glaze however. It
is something you would notice by now.

Let us know about the glazes you use. (if you mix your own, what
ingredients - better yet what recipe are you using).

"Bubbles_" wrote in message
...
Hi DKat! Good to see you!

I am firing bisque to 1050 C.

It usually happens with the really glossy glazes, but I actually had
one bubble on a matte glaze this time as well.

Since the bubbles go all the way in to the clay, do you think I might
be bisque firing too low, so that there are "substances" left in the
clay before the glaze firing?

I do think my oven's thermometer might show a bit higher than it
actually is, so maybe just increasing to 1060 or 1070 would help?

Once again - any input greatly appreciated! Especially since I have a
full load for bisque firing ready.

Marianne



"DKat" wrote in message
...
How high are you bisque firing to? What glaze is this happening with
(is it all glazes, just one, a mix)? We need to know more before
suggestions would be of much use. 40 minutes of hold time is way more
than you should need so something is not as it should be.


"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am
getting rather frustrated by it all. I can "repair" them by adding
glaze to the holes (that are more like inverted craters going all the
way down to the clay) and refiring once or even twice, but I have a
very small kiln at home, and find it both a waste of space and power,
while at the same time not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650,
then up to 1270 and hold for 30 minutes. The cooling was over almost
a day. Policy being that over about 400, I don't even let the cool
air of the laundry room in, but after that, I take out a couple of
plugs (top center and bottom) and under 200 I start opening the lid
of the kiln a little. That shouldn't affect the bubbles, though, as I
am sure they have set at much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

We were fighting bubbles too (not you - them), when we first got into
lowfire clay. It seems that there is some kind of material in the clay that
volatilizes at the maturation point, causing holes in the glaze, and
bubbles, which are really nasty. The solution, using cone 04 clay and 04
glaze, was to bisque to 04 and hold it there a while in the bisque fire, to
let it do its thing. It did make the ware a little less absorbant when
glazing, but it beat the bubbles.

Andrew Werby
www.unitedartworks.com




"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am getting
rather frustrated by it all. I can "repair" them by adding glaze to the
holes (that are more like inverted craters going all the way down to the
clay) and refiring once or even twice, but I have a very small kiln at
home, and find it both a waste of space and power, while at the same time
not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650, then
up to 1270 and hold for 30 minutes. The cooling was over almost a day.
Policy being that over about 400, I don't even let the cool air of the
laundry room in, but after that, I take out a couple of plugs (top center
and bottom) and under 200 I start opening the lid of the kiln a little.
That shouldn't affect the bubbles, though, as I am sure they have set at
much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

Hi Andrew :-)

Glad you won't fight me - I'm a wuss! LOL!

I am also wondering if the bubbles are coming from the ware itself or from
the glaze. Could it be that I have more trouble on the glossy glazes because
they just hold the bubbles better?

The data on my clay says bisque 950-980 degrees C, and I am already firing
it to 1050 (again because then I can combine low-fire glaze and bisque in
the same firing). So then I would have thought I have gotten what needs to
be gotten out of the clay?

The bisque pieces are very nicely absorbant fired to 1050, so I guess I
should try 1060 or 1070 on my next batch?

*reminder to self - scratching head too much may cause splinters in fingers*

Marianne



"Andrew Werby" wrote in message
. ..
We were fighting bubbles too (not you - them), when we first got into
lowfire clay. It seems that there is some kind of material in the clay
that volatilizes at the maturation point, causing holes in the glaze, and
bubbles, which are really nasty. The solution, using cone 04 clay and 04
glaze, was to bisque to 04 and hold it there a while in the bisque fire,
to let it do its thing. It did make the ware a little less absorbant when
glazing, but it beat the bubbles.

Andrew Werby
www.unitedartworks.com




"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am getting
rather frustrated by it all. I can "repair" them by adding glaze to the
holes (that are more like inverted craters going all the way down to the
clay) and refiring once or even twice, but I have a very small kiln at
home, and find it both a waste of space and power, while at the same time
not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650, then
up to 1270 and hold for 30 minutes. The cooling was over almost a day.
Policy being that over about 400, I don't even let the cool air of the
laundry room in, but after that, I take out a couple of plugs (top center
and bottom) and under 200 I start opening the lid of the kiln a little.
That shouldn't affect the bubbles, though, as I am sure they have set at
much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne

Original post below.

I am just wondering about something. My wheel is aluminium, and it oxidizes,
so that I get a black stain on the back of my left hand from centering - but
I also get it in some of the clay that I later reclaim.

Is aluminium a possible cause of these bubbles? Should I stick to
new-bought clay and/or treat my wheel with something so it doesn't let off
particles?

Marianne





"Bubbles_" wrote in message
...
EWWWW!!

I keep getting bubbles on my finished pieces. I have tried up to 40
minutes hold time at 1270 degreess, but they still show up! I am getting
rather frustrated by it all. I can "repair" them by adding glaze to the
holes (that are more like inverted craters going all the way down to the
clay) and refiring once or even twice, but I have a very small kiln at
home, and find it both a waste of space and power, while at the same time
not wanting to "lose" the pieces.

Any ideas on other things I could try? Last kiln was 6 hours to 650, then
up to 1270 and hold for 30 minutes. The cooling was over almost a day.
Policy being that over about 400, I don't even let the cool air of the
laundry room in, but after that, I take out a couple of plugs (top center
and bottom) and under 200 I start opening the lid of the kiln a little.
That shouldn't affect the bubbles, though, as I am sure they have set at
much higher temperatures.

BUT - AGH!!!

Any input and suggestions greatly appreciated!!!

Marianne