Jeff Lawrence on mon 14 sep 98
Hello Sistren & Brethren,
In the course of my glacial-paced volcanic ash tests (two test firings in
five months ... how's that for not rushing things!) I've sifted out a bit
of what my geologist neighbor Dane says is probably cristobalite. some of
them are like little diamonds almost -- up to 2mm or so and glass-clear.
I sift them out because otherwise they stay stuck in the surface of the
pots like 40 grit sandpaper chunks that have lost their way. I mean, these
things do not melt at all at ^6.
Since I try avoid ever throwing anything away, I wonder:
Anybody ever heard of any use for coarse crystobalite sand/crystals? Any
interesting thoughts?
Maybe bullet-proof vest liners for penitential police?
Jeff Lawrence
jml@sundagger.com
Sun Dagger Design
Rt. 1 Box 394L
Espanola, NM 87532
vox/fax 505-753-5913
Chris Leake on wed 16 sep 98
Jeff,
Maybe you could try wedging the crystals into your clay body. It might
create some really interesting effects.
Chris Leake
Jeff Lawrence wrote:
> ----------------------------Original
> message----------------------------
> Hello Sistren & Brethren,
>
> In the course of my glacial-paced volcanic ash tests (two test firings
> in
> five months ... how's that for not rushing things!) I've sifted out a
> bit
> of what my geologist neighbor Dane says is probably cristobalite. some
> of
> them are like little diamonds almost -- up to 2mm or so and
> glass-clear.
>
> I sift them out because otherwise they stay stuck in the surface of
> the
> pots like 40 grit sandpaper chunks that have lost their way. I mean,
> these
> things do not melt at all at ^6.
>
> Since I try avoid ever throwing anything away, I wonder:
>
> Anybody ever heard of any use for coarse crystobalite sand/crystals?
> Any
> interesting thoughts?
>
> Maybe bullet-proof vest liners for penitential police?
>
> Jeff Lawrence
> jml@sundagger.com
> Sun Dagger Design
> Rt. 1 Box 394L
> Espanola, NM 87532
> vox/fax 505-753-5913
Ron Roy on fri 18 sep 98
Keep in mind - cristobalite goes through it's inversions at oven
temperatures - not a good idea for any kind of oven ware.
Cristobalite is some times added - in carefully controlled amounts - to
earthenware bodies to help control crazing. Don'r know what mesh is used.
>----------------------------Original message----------------------------
>Jeff,
>
>Maybe you could try wedging the crystals into your clay body. It might
>create some really interesting effects.
>
>Chris Leake
>
>Jeff Lawrence wrote:
>
>> ----------------------------Original
>> message----------------------------
>> Hello Sistren & Brethren,
>>
>> In the course of my glacial-paced volcanic ash tests (two test firings
>> in
>> five months ... how's that for not rushing things!) I've sifted out a
>> bit
>> of what my geologist neighbor Dane says is probably cristobalite. some
>> of
>> them are like little diamonds almost -- up to 2mm or so and
>> glass-clear.
>>
>> I sift them out because otherwise they stay stuck in the surface of
>> the
>> pots like 40 grit sandpaper chunks that have lost their way. I mean,
>> these
>> things do not melt at all at ^6.
>>
>> Since I try avoid ever throwing anything away, I wonder:
>>
>> Anybody ever heard of any use for coarse crystobalite sand/crystals?
>> Any
>> interesting thoughts?
>>
>> Maybe bullet-proof vest liners for penitential police?
>>
>> Jeff Lawrence
>> jml@sundagger.com
>> Sun Dagger Design
>> Rt. 1 Box 394L
>> Espanola, NM 87532
>> vox/fax 505-753-5913
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Ron Roy on tue 22 sep 98
Keep in mind - cristobalite goes through it's inversions at oven
temperatures - not a good idea for any kind of oven ware.
Cristobalite is some times added - in carefully controlled amounts - to
earthenware bodies to help control crazing. Don'r know what mesh is used.
>----------------------------Original message----------------------------
>Jeff,
>
>Maybe you could try wedging the crystals into your clay body. It might
>create some really interesting effects.
>
>Chris Leake
>
>Jeff Lawrence wrote:
>
>> ----------------------------Original
>> message----------------------------
>> Hello Sistren & Brethren,
>>
>> In the course of my glacial-paced volcanic ash tests (two test firings
>> in
>> five months ... how's that for not rushing things!) I've sifted out a
>> bit
>> of what my geologist neighbor Dane says is probably cristobalite. some
>> of
>> them are like little diamonds almost -- up to 2mm or so and
>> glass-clear.
>>
>> I sift them out because otherwise they stay stuck in the surface of
>> the
>> pots like 40 grit sandpaper chunks that have lost their way. I mean,
>> these
>> things do not melt at all at ^6.
>>
>> Since I try avoid ever throwing anything away, I wonder:
>>
>> Anybody ever heard of any use for coarse crystobalite sand/crystals?
>> Any
>> interesting thoughts?
>>
>> Maybe bullet-proof vest liners for penitential police?
>>
>> Jeff Lawrence
>> jml@sundagger.com
>> Sun Dagger Design
>> Rt. 1 Box 394L
>> Espanola, NM 87532
>> vox/fax 505-753-5913
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Fay & Ralph Loewenthal on thu 24 sep 98
Ron I thought that Cristobalite went through its inversions at
about 570C. This is quite a bit higher than normal oven
temperatures. If I am wrong please let us know at what
temperature the inversion takes place. TIA Ralph in PE SA
Ron Roy on sat 26 sep 98
Hello Ralph,
You are thinking of the quartz inversion at 573C - I am looking at a
dilatometer chart right now - I heat my samples at 3degrees centigrade per
minute and it looks like the cristobalite curve starts up about 100C and
levels off about 180C - that seems fairley standard. I must have at least
100 charts done on bodies and clays so far. Not much to worry about with
cone 6 fired clays or porcelains at any temp. If you are firing stoneware
at cone10 you probably have some and maybe a lot.
Can't say too much right now but I am doing a series of bars for Peter
Sohngen who will write an article on this soon - if you need your body
measured contact me off list.
>----------------------------Original message----------------------------
>Ron I thought that Cristobalite went through its inversions at
>about 570C. This is quite a bit higher than normal oven
>temperatures. If I am wrong please let us know at what
>temperature the inversion takes place. TIA Ralph in PE SA
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
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