Philip Poburka on thu 30 nov 00
Dear Marcia,
Was your cone ten Mug 'standing up', as a Mug might do?
If, snow, thaw, water, to Ice...then, well, it might 'break' it
indeed...if it had a little 'puddle' in it...especially if it narrowed
some...from the bottom, was 'wider' at the bottom.
Had it been on it's 'side', I should be very surprised were a Winter to hurt
it.
Was it on or in 'soil'?
'Frost' can spall porous or simi-porous surfaces sometimes.
I wouldn't suppose the Mug...could 'spall' tho', being vitrious.
Or, 'ice' when becomeing 'ice' of course expands a little from the room it
took up as water. And so, had the Mug been on it's side...my quess is that a
little puddle in it, when freezing, would have just expended it's little
bit, and not broken the Mug.
Life has...many mysteries...!
Phil
lvnev
------Original Message------
From: Marcia Selsor
To: CLAYART@LSV.CERAMICS.ORG
Sent: November 30, 2000 4:28:28 PM GMT
Subject: Re: frostproof - historical reference
Dear Ed,
That was an interesting post but past experience has contrary results. I
accidently left a favorite mug outside in my garden. It was ^10
woodfired made by a famous potter in Montana. I found it cracked with
ice in the spring. Freezing broke it.
Marcia
Ed Kraft wrote:
>
> Evan,
>
> The following is quoted from "A Treatise on Masonry Construction" by Ira
> Osborn Baker last published in 1920. "Formerly, it was believed that the
> absorptive power of a building brick had an important effect upon its
> ability to resist destruction by frost; but experiments and a more careful
> study of experience have shown that the absorptive power of a brick has
> little or nothing to do with its durability. Apparently there are two
> reasons for this: (1) the pores of the brick are not entirely filled with
> water, and consequently the expansion of the water in freezing is
cushioned
> by the air in the pores; and (2) with the more porous bricks, the water
> freezes in the pores without any destructive effect much as water freezes
in
> a large-necked bottle, and with more dense bricks the strength of the
burned
> clay is greater than the expansion force of the water. The absorptive
power
> varies with the chemical composition of the clay, and there seems to be no
> close relation between the absorptive power and the and the strength of a
> brick or the loss of strength by freezing." *
>
> * Report German Royal Experiment Station, Thonindustrie, Zeitung, No. 74,
> 1905.
>
> Ed Kraft
> Earth Arrangements
> 2109 39th St
> Bellingham, WA 98226
> 360 734-6839 ph 360 647 0416 fax
> eartharr@msn.com
>
> ----- Original Message -----
> From: "pedresel"
> To:
> Sent: Monday, November 27, 2000 6:30 PM
> Subject: Re: frostproof - the real test
>
> > I think we don't have all the variables that affect frostproof very well
> > defined. Maybe this is asking for trouble at this time of year, but my
> > terra cotta flower pots are doing fairly well so far. Some have been
> > through several winters and the winters here are not too severe but do
> > go through a number of freeze-thaw cycles. I did have one bird bath
> > form crack but it accumulated standing water (for obvious reasons). I
> > started with ^06-^04 firing and have moved up to ^03 to try and tighten
> > the body and because RR suggested a while ago that a little crystobalite
> > formation would likely be a good thing in terra cotta (if I remember
> > correctly). I suppose I should measure absorption but I can tell you
> > that this body sucks up water to a reasonable degree -- it doesn't pool
> > or run off like stoneware.
> >
> > So what's this mean? I think there is a lot to a clay having strength
> > to withstand the stress of freezing, even if it is porous. I expect a
> > pot that has sintered a fair bit will be a lot stronger than one that
> > has not. By that I mean the materials in the body have started to react
> > to form new crystals such as cristobalite and mullite. I consider this
> > different from vitrification which implys melting to form a glassy
> > phase. By the way I use Seattle Pottery Supply's terra cotta with sand
> > which seems to take a lot of abuse. Supposedly the sand avoids the
> > problem with grog sucking up water. They say the body can be fired to
> > ^1. I think some bodies can inherently stand the freeze thaw cycles
> > while others can't and that problems in forming can increase problems in
> > spallation and cracking -- but I'm not totally sure.
> >
> > There was a good article about frost proof pots in Studio Potter that
> > pointed out that shape and drainage is critical for flower pots. Many
> > pots are broken by the force of the freezing soil so the pots should
> > flare upward, giving the soil room to expand. I suppose the shape
> > factor isn't relevant to tiles, but I think drainage is.
> >
> > -- Evan in W. Richland WA where the clouds are down around our heads.
> >
> >
>
____________________________________________________________________________
> __
> > Send postings to clayart@lsv.ceramics.org
> >
> > You may look at the archives for the list or change your subscription
> > settings from http://www.ceramics.org/clayart/
> >
> > Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>
______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/Tuscany2001.html
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Marcia Selsor on thu 30 nov 00
Dear Phil and Earl,
Here is what I was responding to: "with the more porous bricks, the water
>> freezes in the pores without any destructive effect much as water
freezes in
>> a large-necked bottle, and with more dense bricks the strength of the burned
>> clay is greater than the expansion force of the water."
My mug was cylindrical maybe not "large necked". Too bad. I loved that
mug and the potter doesn't make that style anymore.
Marci
Philip Poburka wrote:
>
> Dear Marcia,
>
> Was your cone ten Mug 'standing up', as a Mug might do?
> If, snow, thaw, water, to Ice...then, well, it might 'break' it
> indeed...if it had a little 'puddle' in it...especially if it narrowed
> some...from the bottom, was 'wider' at the bottom.
>
> Had it been on it's 'side', I should be very surprised were a Winter to hurt
> it.
>
> Was it on or in 'soil'?
> 'Frost' can spall porous or simi-porous surfaces sometimes.
> I wouldn't suppose the Mug...could 'spall' tho', being vitrious.
>
> Or, 'ice' when becomeing 'ice' of course expands a little from the room it
> took up as water. And so, had the Mug been on it's side...my quess is that a
> little puddle in it, when freezing, would have just expended it's little
> bit, and not broken the Mug.
>
> Life has...many mysteries...!
>
> Phil
> lvnev
>
> ------Original Message------
> From: Marcia Selsor
> To: CLAYART@LSV.CERAMICS.ORG
> Sent: November 30, 2000 4:28:28 PM GMT
> Subject: Re: frostproof - historical reference
>
> Dear Ed,
> That was an interesting post but past experience has contrary results. I
> accidently left a favorite mug outside in my garden. It was ^10
> woodfired made by a famous potter in Montana. I found it cracked with
> ice in the spring. Freezing broke it.
> Marcia
>
> Ed Kraft wrote:
> >
> > Evan,
> >
> > The following is quoted from "A Treatise on Masonry Construction" by Ira
> > Osborn Baker last published in 1920. "Formerly, it was believed that the
> > absorptive power of a building brick had an important effect upon its
> > ability to resist destruction by frost; but experiments and a more careful
> > study of experience have shown that the absorptive power of a brick has
> > little or nothing to do with its durability. Apparently there are two
> > reasons for this: (1) the pores of the brick are not entirely filled with
> > water, and consequently the expansion of the water in freezing is
> cushioned
> > by the air in the pores; and (2) with the more porous bricks, the water
> > freezes in the pores without any destructive effect much as water freezes
> in
> > a large-necked bottle, and with more dense bricks the strength of the
> burned
> > clay is greater than the expansion force of the water. The absorptive
> power
> > varies with the chemical composition of the clay, and there seems to be no
> > close relation between the absorptive power and the and the strength of a
> > brick or the loss of strength by freezing." *
> >
> > * Report German Royal Experiment Station, Thonindustrie, Zeitung, No. 74,
> > 1905.
> >
> > Ed Kraft
> > Earth Arrangements
> > 2109 39th St
> > Bellingham, WA 98226
> > 360 734-6839 ph 360 647 0416 fax
> > eartharr@msn.com
> >
> > ----- Original Message -----
> > From: "pedresel"
> > To:
> > Sent: Monday, November 27, 2000 6:30 PM
> > Subject: Re: frostproof - the real test
> >
> > > I think we don't have all the variables that affect frostproof very well
> > > defined. Maybe this is asking for trouble at this time of year, but my
> > > terra cotta flower pots are doing fairly well so far. Some have been
> > > through several winters and the winters here are not too severe but do
> > > go through a number of freeze-thaw cycles. I did have one bird bath
> > > form crack but it accumulated standing water (for obvious reasons). I
> > > started with ^06-^04 firing and have moved up to ^03 to try and tighten
> > > the body and because RR suggested a while ago that a little crystobalite
> > > formation would likely be a good thing in terra cotta (if I remember
> > > correctly). I suppose I should measure absorption but I can tell you
> > > that this body sucks up water to a reasonable degree -- it doesn't pool
> > > or run off like stoneware.
> > >
> > > So what's this mean? I think there is a lot to a clay having strength
> > > to withstand the stress of freezing, even if it is porous. I expect a
> > > pot that has sintered a fair bit will be a lot stronger than one that
> > > has not. By that I mean the materials in the body have started to react
> > > to form new crystals such as cristobalite and mullite. I consider this
> > > different from vitrification which implys melting to form a glassy
> > > phase. By the way I use Seattle Pottery Supply's terra cotta with sand
> > > which seems to take a lot of abuse. Supposedly the sand avoids the
> > > problem with grog sucking up water. They say the body can be fired to
> > > ^1. I think some bodies can inherently stand the freeze thaw cycles
> > > while others can't and that problems in forming can increase problems in
> > > spallation and cracking -- but I'm not totally sure.
> > >
> > > There was a good article about frost proof pots in Studio Potter that
> > > pointed out that shape and drainage is critical for flower pots. Many
> > > pots are broken by the force of the freezing soil so the pots should
> > > flare upward, giving the soil room to expand. I suppose the shape
> > > factor isn't relevant to tiles, but I think drainage is.
> > >
> > > -- Evan in W. Richland WA where the clouds are down around our heads.
> > >
> > >
> >
> ____________________________________________________________________________
> > __
> > > Send postings to clayart@lsv.ceramics.org
> > >
> > > You may look at the archives for the list or change your subscription
> > > settings from http://www.ceramics.org/clayart/
> > >
> > > Moderator of the list is Mel Jacobson who may be reached at
> > melpots@pclink.com.
> >
> >
> ______________________________________________________________________________
> > Send postings to clayart@lsv.ceramics.org
> >
> > You may look at the archives for the list or change your subscription
> > settings from http://www.ceramics.org/clayart/
> >
> > Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
> --
> Marcia Selsor
> selsor@imt.net
> http://www.imt.net/~mjbmls
> http://www.imt.net/~mjbmls/Tuscany2001.html
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/Tuscany2001.html
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