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Röhmertopf?



 
 
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  #1  
Old November 15th 05, 01:27 PM
Bubbles
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Default Röhmertopf?

Hi folks

Hubby is giving me new challenges. This time, he has asked me to make a
röhmertopf.

I have started, but now I am having misgivings. The clay I use is a
high-fire clay that can be fired to 1350 C. But I know that it has to be
low-fired (1000 C), in order to be able to absorb some of the humidity it
needs.

Since it has to be unglazed, I have been "burnishing" it - ie. rubbing it
with a rubber rib, so that the surface is very smooth - also thinking this
will make it easier to keep clean.

But then it hits me.... maybe I am then causing the surface to be more
sealed and impenetrable, which would work against the idea of the pot
absorbing moisture???

I read on the net that the original Röhmertopfs are made of a special clay.
Will my clay work anyway? or should I just chuck the whole thing into my
recycle bin now? :-)

Marianne


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  #2  
Old November 15th 05, 02:23 PM
Xtra News
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Posts: n/a
Default Röhmertopf?


"Bubbles" wrote in message
...
Hi folks

Hubby is giving me new challenges. This time, he has asked me to make a
röhmertopf.

I have started, but now I am having misgivings. The clay I use is a
high-fire clay that can be fired to 1350 C. But I know that it has to be
low-fired (1000 C), in order to be able to absorb some of the humidity it
needs.

Since it has to be unglazed, I have been "burnishing" it - ie. rubbing it
with a rubber rib, so that the surface is very smooth - also thinking this
will make it easier to keep clean.

But then it hits me.... maybe I am then causing the surface to be more
sealed and impenetrable, which would work against the idea of the pot
absorbing moisture???

I read on the net that the original Röhmertopfs are made of a special
clay. Will my clay work anyway? or should I just chuck the whole thing
into my recycle bin now? :-)

Marianne

We were given one as a wedding present. It appeared to be made from just
terracotta clay.
My sister in law makes what she calls chicken bricks.
She throws a large, tall oval shaped pot and completely closes it off.
Turns it so that it is nice and oval, then turns it on its side and flattens
a base, then cuts a lid. She then uses it for cooking like the rohmertopf.
She just uses a basic terracotta.
A


  #3  
Old November 15th 05, 04:20 PM posted to rec.crafts.pottery
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Default Röhmertopf?

The ones I have seen also seem to be just terra cotta. I think terra cotta
is fired to about 2000 degrees F (1100C). That is way beyond what you are
going to get in an oven. You just don't want it to go through thermal shock
(go on to a cold shelf such as the refrigerator after coming out of the
oven). Special clay is needed for using on the stove top for this reason.
In the oven unless it is directly on or under the burner this isn't going to
be an issue. Also don't you start the dish cooking in a cold oven?

Donna

"Xtra News" wrote in message
...

"Bubbles" wrote in message
...
Hi folks

Hubby is giving me new challenges. This time, he has asked me to make a
röhmertopf.

I have started, but now I am having misgivings. The clay I use is a
high-fire clay that can be fired to 1350 C. But I know that it has to be
low-fired (1000 C), in order to be able to absorb some of the humidity it
needs.

Since it has to be unglazed, I have been "burnishing" it - ie. rubbing it
with a rubber rib, so that the surface is very smooth - also thinking
this will make it easier to keep clean.

But then it hits me.... maybe I am then causing the surface to be more
sealed and impenetrable, which would work against the idea of the pot
absorbing moisture???

I read on the net that the original Röhmertopfs are made of a special
clay. Will my clay work anyway? or should I just chuck the whole thing
into my recycle bin now? :-)

Marianne

We were given one as a wedding present. It appeared to be made from just
terracotta clay.
My sister in law makes what she calls chicken bricks.
She throws a large, tall oval shaped pot and completely closes it off.
Turns it so that it is nice and oval, then turns it on its side and
flattens a base, then cuts a lid. She then uses it for cooking like the
rohmertopf. She just uses a basic terracotta.
A



  #4  
Old November 15th 05, 04:38 PM posted to rec.crafts.pottery
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Posts: n/a
Default Röhmertopf?

P.S. This may be what was meant by using a special clay body. Still you
aren't using a glaze so fit isn't an issue and as long as you don't go from
one extreme temperature to another using terra cotta shouldn't be a problem.
I also wouldn't just chuck your piece. You can always use it as a test
piece and surely there must be other uses for it if you decide not to use it
for the oven? You can still glaze it even though it has been burnished if
that is what you would like.

http://www.digitalfire.com/education/glossary/ (digitalfire is a must have
link)

Ovenware
Ovenware (and flameware) clay bodies have a lower thermal expansion so they
can withstand more sudden changes in temperature. Ovenware bodies should
thus have much lower free quartz content and employ low expansion minerals
like mullite, pyrophyllite, petalite, kyanite and spodumene. While many
potters make ware for use in the oven using standard clay bodies, ovenware
manufacturers (like Corning) would object to calling this 'ovenware'. This
is because they dedicate considerable resources to producing bodies and
glazes that have a much lower thermal expansion and therefore are much more
suitable. Potters are able to get away with using standard bodies and glazes
by making sure the glaze fits well (no crazing), avoiding high-quartz and
highly vitreous bodies, firing evenly to reduce built-in stresses,
maintaining an even cross section, avoiding angular contours and larger
sizes with broad flat bottoms and telling customers to be careful about
subjecting ware to sudden temperature change.

Glaze fit is a major problem in designing an ovenware body since common
glazes will craze. It is much easier to make a low expansion clay body than
a glaze, thus it is normal to compromise the lowest possible expansion on
the body in order to get a reliable glaze fit. Low expansion glazes
typically employ lithia and high silica and alumina and avoid sodium and
potassium. It is much easier to make a low expansion glaze at high
temperatures where silica and alumina can be higher.

There are two mechanisms to creating a low expansion body: By firing to form
crystalline minerals that have low expansion or by employing mineral
particles and fluid glasses in the body recipe have low expansion. The
former produces a more vitreous body and requires much more expertise and
test equipment. The later is a bit of a 'crowbar' approach and is dependent
on not firing to full maturity (otherwise mineral species can be dissolved
by the feldspar in the body and the low expansion effect lost). The latter
creates a bit of a 'tug-of-war' in the body since some particles (like
quartz) want to expand on heating and contract on cooling whereas others
(like kyanite, mullite) want to remain stable. Furthermore, the glass that
glues all the particles together introduces a third expansion dynamic to the
matrix.


  #5  
Old November 15th 05, 07:25 PM posted to rec.crafts.pottery
external usenet poster
 
Posts: n/a
Default Röhmertopf?

Bubbles wrote:
Hi folks

Hubby is giving me new challenges. This time, he has asked me to make a
röhmertopf.

I have started, but now I am having misgivings. The clay I use is a
high-fire clay that can be fired to 1350 C. But I know that it has to be
low-fired (1000 C), in order to be able to absorb some of the humidity it
needs.

Since it has to be unglazed, I have been "burnishing" it - ie. rubbing it
with a rubber rib, so that the surface is very smooth - also thinking this
will make it easier to keep clean.

But then it hits me.... maybe I am then causing the surface to be more
sealed and impenetrable, which would work against the idea of the pot
absorbing moisture???

I read on the net that the original Röhmertopfs are made of a special clay.
Will my clay work anyway? or should I just chuck the whole thing into my
recycle bin now? :-)


I had an "original" Römertopf, the bottom part was glazed on the inside,
the top not glazed at all. I used it a few times, and found that it
doesn't do anything which an ordinary pan wouldn't do, it only takes a
whole lot longer. It take hours until ordinary vegetables are done,
hours until meat is tender, if you think of the energy it takes in an
electric oven, i decided, it wasn't worth it and got rid of it again.
If the bottom part is unglazed, it absorbs fat and becomes rancid after
a short time, hence all the Römertöpfe you get really cheat at
fleamarktes. I decided, it was just some kind of fad, and gave up on them.

Schöne Grüsse, Monika
--
Monika Schleidt

www.schleidt.org/MSKeramik
if you wish to write me a mail, remove the number from my user name
  #6  
Old November 15th 05, 08:41 PM posted to rec.crafts.pottery
external usenet poster
 
Posts: n/a
Default Röhmertopf?


"Monika Schleidt" wrote in message
...
Bubbles wrote:
Hi folks

Hubby is giving me new challenges. This time, he has asked me to make a
röhmertopf.

I have started, but now I am having misgivings. The clay I use is a
high-fire clay that can be fired to 1350 C. But I know that it has to be
low-fired (1000 C), in order to be able to absorb some of the humidity it
needs.

Since it has to be unglazed, I have been "burnishing" it - ie. rubbing it
with a rubber rib, so that the surface is very smooth - also thinking
this will make it easier to keep clean.

But then it hits me.... maybe I am then causing the surface to be more
sealed and impenetrable, which would work against the idea of the pot
absorbing moisture???

I read on the net that the original Röhmertopfs are made of a special
clay. Will my clay work anyway? or should I just chuck the whole thing
into my recycle bin now? :-)


I had an "original" Römertopf, the bottom part was glazed on the inside,
the top not glazed at all. I used it a few times, and found that it
doesn't do anything which an ordinary pan wouldn't do, it only takes a
whole lot longer. It take hours until ordinary vegetables are done, hours
until meat is tender, if you think of the energy it takes in an electric
oven, i decided, it wasn't worth it and got rid of it again.
If the bottom part is unglazed, it absorbs fat and becomes rancid after a
short time, hence all the Römertöpfe you get really cheat at fleamarktes.
I decided, it was just some kind of fad, and gave up on them.

Schöne Grüsse, Monika
--
Monika Schleidt

www.schleidt.org/MSKeramik
if you wish to write me a mail, remove the number from my user name


The one we had was unglazed, but we did worry about the hygene thing. It is
now used as a planter )
It was a proper romertopfe mould made with the name across it, a recipe book
etc.
I like the tagines more, the morroccan style casserole, here is one
http://www.crateandbarrel.com/family.aspx?c=520&f=9064
I have made them with the lid handle a bit wider so that you can turn it
over and use it as a serving bowl.


  #7  
Old November 15th 05, 11:19 PM posted to rec.crafts.pottery
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Default R����������


The one we had was unglazed, but we did worry about the hygene thing. It is
now used as a planter )


I'd have thought that (see eg http://fantes.com/romertopf.htm) baking
for an hour at 200degC would kill most bugs!
  #8  
Old November 16th 05, 12:01 AM posted to rec.crafts.pottery
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Posts: n/a
Default R??????????


"pbhj" wrote in message
...

The one we had was unglazed, but we did worry about the hygene thing. It
is now used as a planter )


I'd have thought that (see eg http://fantes.com/romertopf.htm) baking for
an hour at 200degC would kill most bugs!


Yeah, probably, but then you clean it as much as you can and let it dry, but
it never looks completely clean again. Its more a feeling thing probably
than a real hygene issue. The one here looks very like the one we have,
part of the reason we stopped using it though is because the lid had a bit
crack in it, don't remember how it happened. It has a little walnut tree
planted in it now, which I must soon transplant to give growing space.


  #9  
Old November 16th 05, 12:53 AM posted to rec.crafts.pottery
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Posts: n/a
Default Röhmertopf?


"Monika Schleidt" wrote in message
...

I had an "original" Römertopf, the bottom part was glazed on the inside,
the top not glazed at all. I used it a few times, and found that it
doesn't do anything which an ordinary pan wouldn't do, it only takes a
whole lot longer. It take hours until ordinary vegetables are done, hours
until meat is tender, if you think of the energy it takes in an electric
oven, i decided, it wasn't worth it and got rid of it again.
If the bottom part is unglazed, it absorbs fat and becomes rancid after a
short time, hence all the Römertöpfe you get really cheat at fleamarktes.
I decided, it was just some kind of fad, and gave up on them.


If the original can be glazed, then so can my "copy". I also like the idea
of hygenic surfaces for food. Might be that temperature kills the bugs, but
I still see a porous surface - yaknow?

I can agree with your arguments, Monika - and also another that this thing
is going to take a lot of space in some cupboard. I have forwarded the
arguments to my husband, and will just keep the whole thing from drying
until we decide what to do. I have non-poison glazes only, so will use one
of the 1000C ones on the inside bottom.

You are supposed to soak the whole thing in water for ages before use - and
then soak for 10-15 minutes before each use - put in a cold oven - and never
on a cold surface when taking out of the oven. Sounds pretty delicate to me!
Hehe!

I'll see what I do - but thank EVERYONE for their ever fantastic responses!
You guys inspire me!

Marianne


  #10  
Old November 16th 05, 02:39 AM posted to rec.crafts.pottery
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Posts: n/a
Default Röhmertopf?

They are not supposed to be glazed. They are supposed to be soaked in water
before putting food in them and then put in the oven. It is part of the
cooking method. The food is steamed and then dry roasted which is a bit
odd. I found that I wasn't fond of mine. I have heard good things about
the tagines mentioned.

Donna

"Bubbles" wrote in message
...

"Monika Schleidt" wrote in message
...

I had an "original" Römertopf, the bottom part was glazed on the inside,
the top not glazed at all. I used it a few times, and found that it
doesn't do anything which an ordinary pan wouldn't do, it only takes a
whole lot longer. It take hours until ordinary vegetables are done, hours
until meat is tender, if you think of the energy it takes in an electric
oven, i decided, it wasn't worth it and got rid of it again.
If the bottom part is unglazed, it absorbs fat and becomes rancid after a
short time, hence all the Römertöpfe you get really cheat at fleamarktes.
I decided, it was just some kind of fad, and gave up on them.


If the original can be glazed, then so can my "copy". I also like the idea
of hygenic surfaces for food. Might be that temperature kills the bugs,
but I still see a porous surface - yaknow?

I can agree with your arguments, Monika - and also another that this thing
is going to take a lot of space in some cupboard. I have forwarded the
arguments to my husband, and will just keep the whole thing from drying
until we decide what to do. I have non-poison glazes only, so will use one
of the 1000C ones on the inside bottom.

You are supposed to soak the whole thing in water for ages before use -
and then soak for 10-15 minutes before each use - put in a cold oven - and
never on a cold surface when taking out of the oven. Sounds pretty
delicate to me! Hehe!

I'll see what I do - but thank EVERYONE for their ever fantastic
responses! You guys inspire me!

Marianne



 




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