Alisa and Claus Clausen on thu 9 mar 00
------------------
Hi Peter,
Thanks very much. I was maybe temporarily elated yesterday when I had no
shivering over the engobes. BUT, I am not yet convinced, I still think =
that
particular
glaze was the problem, and inclined also now to say that it is that =
particular
batch.
I used the same glaze at home, mixed by myself, and it is sticking.
But, but again, I am eager to try your recommended tests, because I am not
convinced that that the engobes fit the white body.
I have tried the glaze that I mixed on 4 clay bodies now,
paper clay, a marbled iron body, white ware and flecked stoneware.
All sticking.
Now bring in the engobes.
It did not peel away from the engobed area (only in one small spot on a pot =
I
painted
when perhaps too dry and maybe too thick in that spot).
But it had consistently sprung off the lips of the whiteware pots.
None of these pots are being sold, etc. They are made by hobbyists in the
community
studio and the ones that shivered were thrown away and the makers told in =
detail
why they may not be retrieved.)
I will let you know what I find, and hopefully, again, I have the feeling it=
is
this
one batch of glaze. Wouldn't that be great?=21
Thanks again,
interesting information you sent.
Alisa in Denmark
Alisa and Claus Clausen on fri 10 mar 00
------------------
Dear Ron,
My original query was that I wanted to know in theory, if shivering can be
caused by a bad fit between slips and bodies,
or only due to a bad fit between bodies and glazes. Peter was kind to
give me that information.
These particular slips and transparent glaze are all commercially made and =
have
been used over approx. 8 months the community studio. Of course I made test
tiles, 2 for each color, one glazed with gloss transparent, one with mat.
They fired fine, no shivering. But the tiles were flat, no lips to get a
thicker
amount of glaze settling. At home I tried these commercial engobes on
four types of cone 6 stoneware. Only the paperclay crackled, the other 3 =
fine.
The paperclay test was painted, as opposed to dipped, so I may have applied
the glaze too thickly. As said, the glaze requires a low viscosity (40).
Am I am reading your message to say I am lazy and expect this all these
materials to work presto bingo?=21..well, that sure would be nice.
I am not a lazy dum dum. However, when things do go wrong,
sometimes it takes time to decide what the variables are and where
to begin a controlled leaping off point to make things correct.
Thus my queries to Clayart.
Recently I have seen a fair amount of lips shivering. Therefore I am trying =
to
diagnose the problem by looking at the easiest problem to fix, and go on
progressively to the more elaborate problems to fix.
I have seen the engobes fit the white body with the transp. glaze.
Now I have a problem.
What has changed?
The batch of glaze.
That is why I am starting with the glaze.
I do have a good idea of what fit is about. That is what lead me to my =
concern
about
perhaps the engobe not fitting a particular body.
It is also my point that for my own work I make engobes made from the same =
body
of the pots that I am going to paint the engobes on. Good fit.
The body that I use for brushing engobes is white, so no coverage problem.
I was pondering if one is assured a fit with the same body engobe,
what would be the advantage of mixing up engobes from a different reciepe
such a standard white, or Bringle, etc.
But that could be just as simple as what you said, to cover a darker
body. But if one used a white body, are there any advantages to mixing
up a different receipe engobe?
I would be interested to hear your opinion on that.
Best regards,
Alisa in Denmark
-----Oprindelig meddelelse-----
Fra: Ron Roy =3Cronroy=40pop.total.net=3E
Til: CLAYART=40LSV.UKY.EDU =3CCLAYART=40LSV.UKY.EDU=3E
Dato: 9. marts 2000 22:09
Emne: Re: Sv: Another shivering engobe problem
----------------------------Original message----------------------------
Why engobes are not tested for fit with both bodies and glazes is a mystery
to me.
I recommend making test tiles out of it and trying your glazes on them. If
they react the way your body does with your glazes then you are on the
right track.
The idea of inserting a layer of anything between clay and glaze and
expecting it to be compatible without any experimentation is simply not
understanding what fit is about.
I recommend making slips out of the same body you are throwing with - if
possible. If you are putting a light slip over a dark body then there is
work to be done and it is easier said than done.
RR
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Ron Roy on sun 12 mar 00
Dear Alisa,
First let me say I'm sorry to have been so abrupt in my post on this - I
was tired and should have waited longer and been more careful. My remarks
were not so much to you as they were an expression of my concern that we
all approach this subject with more care and understanding. I can see you
have been diligent and careful - more than most.
It is my opinion that it is either the slip or the glaze - as it always is
with fit problems - an incompatibility rather than blaming one or the
other.
It may also be the body underneath both - it would help if I knew what the
chips looked like. The bonding of all three layers - or rather the lack of
bonding can be part of this problem. A slip that does not have enough flux
will have a difficult time staying on the body - it just never gets melted
together properly. I would be interested to know what happens if you soak -
or if you do if you soak longer.
The other burning question is - can you trace this change to new body, slip
or glaze - sometimes manufactures put a batch number on their products -
this would be most helpful to both you and them when things go wrong. What
do they say about the shivering?
I suppose the question now is - when the glaze is on just the slip alone -
a sharp edge - does it shiver? Perhaps all three should be tested - glaze
on body and slip on body as well. Freezing the results would continue the
cooling more and would help aggravate the problem.
When you say the combination only crazed on the paper clay - and the others
were fine - the trouble with shivering problems is they are more difficult
to see. There are stresses set up when you have the opposite of crazing
that can be dormant for quite a while. What I am saying here is - in many
cases it is more difficult to spot the imbalances that can result in
shivering and dunting of ware.
This would all be so easy to deal with if I could see the recipe of the
glazes - it is usually quite evident when the expansion is calculated to
predict this kind of problem - especially when one glaze is crazing.
You are asking if it would be an advantage to simply mix up engobes and try
them - right? I think the answer is - maybe - you would have to test till
you found one that worked but at least you would know what you are working
with and could change it.
As I have said - I wish I had more experience in this - I have none - I can
change glazes to fit but slips are a much greater problem. I am working on
a few slips for others at the moment and I will get smarter at it as I get
some experience.
In the mean time - please keep me informed about your problem - I may be
able to help. I have found I do better at this kind of thing when I have
had time to think about them.
In the meantime - don't be mad at an old man who is ashamed of being unkind.
RR
>----------------------------Original message----------------------------
>Dear Ron,
>My original query was that I wanted to know in theory, if shivering can be
>caused by a bad fit between slips and bodies,
>or only due to a bad fit between bodies and glazes. Peter was kind to
>give me that information.
>
>These particular slips and transparent glaze are all commercially made and have
>been used over approx. 8 months the community studio. Of course I made test
>tiles, 2 for each color, one glazed with gloss transparent, one with mat.
>They fired fine, no shivering. But the tiles were flat, no lips to get a
>thicker
>amount of glaze settling. At home I tried these commercial engobes on
>four types of cone 6 stoneware. Only the paperclay crackled, the other 3 fine.
>The paperclay test was painted, as opposed to dipped, so I may have applied
>the glaze too thickly. As said, the glaze requires a low viscosity (40).
>
>Am I am reading your message to say I am lazy and expect this all these
>materials to work presto bingo?!..well, that sure would be nice.
>I am not a lazy dum dum. However, when things do go wrong,
>sometimes it takes time to decide what the variables are and where
>to begin a controlled leaping off point to make things correct.
>Thus my queries to Clayart.
>
>Recently I have seen a fair amount of lips shivering. Therefore I am trying to
>diagnose the problem by looking at the easiest problem to fix, and go on
>progressively to the more elaborate problems to fix.
>
>I have seen the engobes fit the white body with the transp. glaze.
>Now I have a problem.
>What has changed?
>The batch of glaze.
>That is why I am starting with the glaze.
>
>I do have a good idea of what fit is about. That is what lead me to my concern
>about
>perhaps the engobe not fitting a particular body.
>
>It is also my point that for my own work I make engobes made from the
>same body
>of the pots that I am going to paint the engobes on. Good fit.
>The body that I use for brushing engobes is white, so no coverage problem.
>
>I was pondering if one is assured a fit with the same body engobe,
>what would be the advantage of mixing up engobes from a different reciepe
>such a standard white, or Bringle, etc.
>
>But that could be just as simple as what you said, to cover a darker
>body. But if one used a white body, are there any advantages to mixing
>up a different receipe engobe?
>
>I would be interested to hear your opinion on that.
>
>Best regards,
>Alisa in Denmark
>
>
>
>-----Oprindelig meddelelse-----
>Fra: Ron Roy
>Til: CLAYART@LSV.UKY.EDU
>Dato: 9. marts 2000 22:09
>Emne: Re: Sv: Another shivering engobe problem
>
>
>
>
>----------------------------Original message----------------------------
>Why engobes are not tested for fit with both bodies and glazes is a mystery
>to me.
>
>I recommend making test tiles out of it and trying your glazes on them. If
>they react the way your body does with your glazes then you are on the
>right track.
>
>The idea of inserting a layer of anything between clay and glaze and
>expecting it to be compatible without any experimentation is simply not
>understanding what fit is about.
>
>I recommend making slips out of the same body you are throwing with - if
>possible. If you are putting a light slip over a dark body then there is
>work to be done and it is easier said than done.
>
>RR
>
>Ron Roy
>93 Pegasus Trail
>Scarborough
>Ontario, Canada
>M1G 3N8
>Evenings 416-439-2621
>Fax 416-438-7849
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
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