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Glaze remelting/refiring



 
 
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  #1  
Old November 20th 07, 04:28 PM posted to rec.crafts.pottery
Bubbles_
external usenet poster
 
Posts: 81
Default Glaze remelting/refiring

Hi again, folks

When refiring a glaze, does it melt again at the same or similar melting
point/temperature as it did the first time around? Stupid question, maybe,
but I'm still battling those pock marks and feel knowing for sure would be a
great help.

Thanks all! Back to glazing and firing so I have enough Christmas presents
for my family back in Norway - off on Sunday to visit them! WHEEE!

Marianne


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  #2  
Old November 20th 07, 06:41 PM posted to rec.crafts.pottery
DKat
external usenet poster
 
Posts: 99
Default Glaze remelting/refiring

Not stupid question at all. The second firing of a glaze is not the same as
the first. Before the first firing you had one set of chemicals. After the
firing you have a glass which has undergone chemical changes. Your Carbon,
Sulfur, Nitrogen, etc. have all been removed from the glaze. It isn't even
that you have a frit because glass is oddly a liquid in many ways.

Also the second fire may not get rid of your blisters - it may in fact make
them worse.

If you can sand the blisters down as much as possible and then coat them
with a glaze that tends to be a bit on the runny side... maybe. JMO.

Good luck and enjoy your visit!

Donna



"Bubbles_" wrote in message
...
Hi again, folks

When refiring a glaze, does it melt again at the same or similar melting
point/temperature as it did the first time around? Stupid question, maybe,
but I'm still battling those pock marks and feel knowing for sure would be
a great help.

Thanks all! Back to glazing and firing so I have enough Christmas presents
for my family back in Norway - off on Sunday to visit them! WHEEE!

Marianne



  #3  
Old November 20th 07, 06:45 PM posted to rec.crafts.pottery
Bubbles_
external usenet poster
 
Posts: 81
Default Glaze remelting/refiring

Hi D! Thanks for the quick reply!

So far, with my glazes, a second firing has never made them worse. I see
what you mean about substances being gone. None of my glazes are runny,
though - the only thing is the beautifier, and that has caused many craters
in the past, so I don't trust it much these days. Mind you, I think I was
putting it on wayyy too thick.

Would setting top temperature a couple of degrees higher help in melting the
edges of the craters?

Marianne




"DKat" wrote in message
...
Not stupid question at all. The second firing of a glaze is not the same
as the first. Before the first firing you had one set of chemicals.
After the firing you have a glass which has undergone chemical changes.
Your Carbon, Sulfur, Nitrogen, etc. have all been removed from the glaze.
It isn't even that you have a frit because glass is oddly a liquid in many
ways.

Also the second fire may not get rid of your blisters - it may in fact
make them worse.

If you can sand the blisters down as much as possible and then coat them
with a glaze that tends to be a bit on the runny side... maybe. JMO.

Good luck and enjoy your visit!

Donna



"Bubbles_" wrote in message
...
Hi again, folks

When refiring a glaze, does it melt again at the same or similar melting
point/temperature as it did the first time around? Stupid question,
maybe, but I'm still battling those pock marks and feel knowing for sure
would be a great help.

Thanks all! Back to glazing and firing so I have enough Christmas
presents for my family back in Norway - off on Sunday to visit them!
WHEEE!

Marianne





  #4  
Old November 20th 07, 08:10 PM posted to rec.crafts.pottery
DKat
external usenet poster
 
Posts: 99
Default Glaze remelting/refiring

Your glaze in the second firing is actually going to be melting at a lower
temperature so unless the firing was at too low a temperature for your
glazes to begin with then my answer would be no. I would not increase the
temperature. This is one of those cases where you just have to play with it
and see what works. As I remember you said that you used a really long
soak. If not, I would try soaking at top temperature but keep in mind that
the soak is going to increase your heat work (making it a higher firing than
what you would have without the soak) so you might actually want to drop the
temperature some (8 C). I would soak at least 10 minutes but over soaking
is hard on your elements.

Donna


"Bubbles_" wrote in message
...
Hi D! Thanks for the quick reply!

So far, with my glazes, a second firing has never made them worse. I see
what you mean about substances being gone. None of my glazes are runny,
though - the only thing is the beautifier, and that has caused many
craters in the past, so I don't trust it much these days. Mind you, I
think I was putting it on wayyy too thick.

Would setting top temperature a couple of degrees higher help in melting
the edges of the craters?

Marianne




"DKat" wrote in message
...
Not stupid question at all. The second firing of a glaze is not the same
as the first. Before the first firing you had one set of chemicals.
After the firing you have a glass which has undergone chemical changes.
Your Carbon, Sulfur, Nitrogen, etc. have all been removed from the glaze.
It isn't even that you have a frit because glass is oddly a liquid in
many ways.

Also the second fire may not get rid of your blisters - it may in fact
make them worse.

If you can sand the blisters down as much as possible and then coat them
with a glaze that tends to be a bit on the runny side... maybe. JMO.

Good luck and enjoy your visit!

Donna



"Bubbles_" wrote in message
...
Hi again, folks

When refiring a glaze, does it melt again at the same or similar melting
point/temperature as it did the first time around? Stupid question,
maybe, but I'm still battling those pock marks and feel knowing for sure
would be a great help.

Thanks all! Back to glazing and firing so I have enough Christmas
presents for my family back in Norway - off on Sunday to visit them!
WHEEE!

Marianne







  #5  
Old November 20th 07, 08:47 PM posted to rec.crafts.pottery
charlie
external usenet poster
 
Posts: 29
Default Glaze remelting/refiring


"DKat" wrote in message
news
Your glaze in the second firing is actually going to be melting at a lower
temperature so unless the firing was at too low a temperature for your
glazes to begin with then my answer would be no. I would not increase the
temperature. This is one of those cases where you just have to play with
it and see what works. As I remember you said that you used a really long
soak. If not, I would try soaking at top temperature but keep in mind
that the soak is going to increase your heat work (making it a higher
firing than what you would have without the soak) so you might actually
want to drop the temperature some (8 C). I would soak at least 10 minutes
but over soaking is hard on your elements.

Donna


"Bubbles_" wrote in message
...
Hi D! Thanks for the quick reply!

So far, with my glazes, a second firing has never made them worse. I see
what you mean about substances being gone. None of my glazes are runny,
though - the only thing is the beautifier, and that has caused many
craters in the past, so I don't trust it much these days. Mind you, I
think I was putting it on wayyy too thick.

Would setting top temperature a couple of degrees higher help in melting
the edges of the craters?

Marianne




"DKat" wrote in message
...
Not stupid question at all. The second firing of a glaze is not the
same as the first. Before the first firing you had one set of
chemicals. After the firing you have a glass which has undergone
chemical changes. Your Carbon, Sulfur, Nitrogen, etc. have all been
removed from the glaze. It isn't even that you have a frit because glass
is oddly a liquid in many ways.

Also the second fire may not get rid of your blisters - it may in fact
make them worse.

If you can sand the blisters down as much as possible and then coat them
with a glaze that tends to be a bit on the runny side... maybe. JMO.

Good luck and enjoy your visit!

Donna



"Bubbles_" wrote in message
...
Hi again, folks

When refiring a glaze, does it melt again at the same or similar
melting point/temperature as it did the first time around? Stupid
question, maybe, but I'm still battling those pock marks and feel
knowing for sure would be a great help.

Thanks all! Back to glazing and firing so I have enough Christmas
presents for my family back in Norway - off on Sunday to visit them!
WHEEE!

Marianne


can you sandblast the objects and recoat with the same glaze, then refire to
the same temp?


  #6  
Old November 20th 07, 09:36 PM posted to rec.crafts.pottery
Bubbles_
external usenet poster
 
Posts: 81
Default Glaze remelting/refiring


"charlie" wrote in message
...

can you sandblast the objects and recoat with the same glaze, then refire
to the same temp?


Seeing as the glaze bubbled the first time, it might well do it again, so I
would be careful with that.

Also, "just" grinding the pock marks down and then adding a little glaze to
those areas has worked for me before.

Marianne


  #7  
Old November 20th 07, 09:39 PM posted to rec.crafts.pottery
Bubbles_
external usenet poster
 
Posts: 81
Default Glaze remelting/refiring


"DKat" wrote in message
news
Your glaze in the second firing is actually going to be melting at a lower
temperature so unless the firing was at too low a temperature for your
glazes to begin with then my answer would be no. I would not increase the
temperature. This is one of those cases where you just have to play with
it and see what works. As I remember you said that you used a really long
soak. If not, I would try soaking at top temperature but keep in mind
that the soak is going to increase your heat work (making it a higher
firing than what you would have without the soak) so you might actually
want to drop the temperature some (8 C). I would soak at least 10 minutes
but over soaking is hard on your elements.


I think I am on the trail of the cause for MY pock marks now - the soak
temperature. I tried 1240 - there were less pocks - I tried 1245 and there
were more again. This kiln today is going to soak 30 minutes at 1235.

I am making it a bit harder for myself in that I use different glazes and
combinations of glazes most of the time - so that I have to look at all
angles of the firings and glazes to see what works where. I am making
exacting notes these days, though, so I can track many aspects I wasn't able
to before.

I'm sure I'll be back talking to you before the holidays, so I will just
wish you happy glazing for now! :-)

Marianne


  #8  
Old November 20th 07, 10:07 PM posted to rec.crafts.pottery
charlie
external usenet poster
 
Posts: 29
Default Glaze remelting/refiring


"Bubbles_" wrote in message
...

"charlie" wrote in message
...

can you sandblast the objects and recoat with the same glaze, then refire
to the same temp?


Seeing as the glaze bubbled the first time, it might well do it again, so
I would be careful with that.


not necessarily. if the gases (or the components of the minerals that
produce the gases) that caused the bubbles are gone, then only the newly
added glaze would cause bubbles, if any.

Also, "just" grinding the pock marks down and then adding a little glaze
to those areas has worked for me before.

Marianne



  #9  
Old November 21st 07, 02:33 AM posted to rec.crafts.pottery
Bubbles_
external usenet poster
 
Posts: 81
Default Glaze remelting/refiring


"charlie" wrote in message
...

"Bubbles_" wrote in message
...

"charlie" wrote in message
...

can you sandblast the objects and recoat with the same glaze, then
refire to the same temp?


Seeing as the glaze bubbled the first time, it might well do it again, so
I would be careful with that.


not necessarily. if the gases (or the components of the minerals that
produce the gases) that caused the bubbles are gone, then only the newly
added glaze would cause bubbles, if any.


Which is why I would rather keep the old glaze as much as possible.

Marianne


 




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