mel jacobson on fri 9 oct 09
in about 1965 i did a series of pots that had melted glass in
the bottom.
i knew then, and still know that sharp glass edges can splinter
off and become a part of food. we don't want that.
i in/curved my flat dish/pots, made a well of sorts and added
broken glass and some cobalt, copper etc. just sprinkled it
on the glass.
we knew it would crackle like mad..and it did.
in keeping with some new pallet ideas, brighter colors
for my sales...i am bringing it back.
folks just like the pots.
i am very cautious telling potters not to use this in
food serving dishes, but some don't listen.
it takes just one sliver of glass breaking off, bingo...naughty.
i have these pots sort of listed as trivets, decorative pots
for tables...etc.
i added a pix of one of the 1965 pots on my website/clayart page.
i use celedon as a base glaze...then add the glass.
i will photograph two that just came out of the kiln/i used marbles.
but, am running low on my bags of marbles.
i will use fine wine bottles for my next series.
colleen works in a bar, and will save all the glass exotic bottles.
i bet those blue vodka bottles will be nice.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
new book: http://www.21stcenturykilns.com
ivor & olive lewis on sat 10 oct 09
Whenever this topic is raised I recall the time I spent In Sunderland, Co.
Durham, UK.
After a good storm and the sea had settled down we used to go to the beache=
s
and troll along the tide line looking for coloured glass nodules. Some had
high polish but most were just sanded. Put into jars and filled with water
then placed where the Sun would illuminate them they were colourful and
decorative. Those who attended pottery classes used them in the way Mel
describes but because they were already coloured there was no need to add
metallic oxides or carbonates.
Where had the glass come from. Well, during the time of the Venerable Bede.
about 700 CE and the building of the churches, an industry was established
to create window glass for the church and cathedral windows. Sunderland was
one main source of coloured glass for some 1200 years. So some of those
nodules we collected were ancient.
Best regards,
Ivor Lewis,
Redhill,
South Australia
Keith Arbogast on sat 10 oct 09
Dear Mel,
There is a wonderful potter from Florida, Peter Streit, who puts
colored glass in the bottom of bowls and the effect is stunning. I
don't know the type of glass or the firing details, but I think he
puts a solid piece of clear glass over the broken pieces of colored
glass to make a smooth surface.
Best wishes,
Keith Arbogast
Bloomington, IN
Tommy Humphries on sat 10 oct 09
Years ago I made a set of steins for a friend of mine. After firing we
placed colored marbles in them and melted the glass in his annealing
kiln firing down and soaking to temper the glass so it would not
craze. Once cooled I ground the clay off the bottom of the steins and
polished the glass with my diamond lapidary wheels. Was way cool
drinkin a beer with the light coming through the bottom of the mug.
Tommy Humphries
On Oct 9, 2009, at 12:22 PM, mel jacobson wrote:
> in about 1965 i did a series of pots that had melted glass in
> the bottom.
>
> i will photograph two that just came out of the kiln/i used marbles.
> but, am running low on my bags of marbles.
>
Too bad Mel is losing his marbles!
> mel
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
> new book: http://www.21stcenturykilns.com
Snail Scott on sun 11 oct 09
On Oct 10, 2009, at 3:49 PM, Keith Arbogast wrote:
> There is a wonderful potter from Florida, Peter Streit, who puts
> colored glass in the bottom of bowls and the effect is stunning. I
> don't know the type of glass or the firing details, but I think he
> puts a solid piece of clear glass over the broken pieces of colored
> glass to make a smooth surface...
The 'cracked ice' effect is due to incompatible CoE
between the clay and glass, not the chunkiness
of the glass pieces. Putting more glass over it
would change nothing. Would it really be possible
to have a glaze with a CoE compatible with the
clay which wouldn't be also be cracked by the
stresses in the underlying glass? Seems unlikely.
The cracking, remember, happens in the lower
stages of cooling, after things haver solidified to
the point where they can't accommodate any
further dimensional changes. Any normally
non-crazing glaze or even a CoE-compatible
glass would probably be cracked by the forces
of the glass splitting up underneath it.
Tommy Humphries mentioned annealing (controlled
slow cooling) to reduce cracking, but if cracking is
the look that's wanted, annealing won't help.
A type of cracked-ice glaze is currently popular
in commercially-made ware, but it's a thin glaze,
well-bonded to the clay underneath, and a far cry
from the misfit of regular melted glass puddles.
Is Peter Streit's glaze truly smooth on top, or are
the crazing lines just not very sharp or open?
Sometimes they aren't obvious, but are they truly
absent? Please tell more...
-Snail
Keith Arbogast on mon 12 oct 09
"Is Peter Streit's glaze truly smooth on top, or are
the crazing lines just not very sharp or open?
Sometimes they aren't obvious, but are they truly
absent? Please tell more..."
Hi Snail,
Now I've done it... My intention was to offer the idea that the
broken or cracked surface could be covered with a clear layer to
eliminate the roughness. I don't know the technique in any detail.
You make good points. They seem watertight. All I can say is my
recollection is that the surface was smooth, but the underlying
colored glass was broken. But, this was over two years ago. He was in
a booth next to us at the Fourth Street Festival in Bloomington. If
I remember right... he said he put a piece of clear glass on top to
achieve that. Maybe I dreamed that. I would not testify that it was
table top smooth, but it was not rough or sharp. The effect of the
radiant amber and blue glass in the bottoms of ceramic bowls was quite
something. Well worth investigating. I'm sorry I don't know the type
of glass and clay he combines and how he fires them. I do not have an
e-mail address for Peter Streit, but you can see some of his work at http:/=
/www.tampatourdeclay.com/gallery/
--just none with a glass layer showing. The Web page contains an
address and a telephone number, if anyone wishes to ask him directly.
Best wishes,
Keith Arbogast
David Woof on mon 12 oct 09
The local glass man told me that common window glass contains lead=3D2C (oh=
hh=3D
fear and dread) but if this is factual information=3D2C we should be awar=
e.=3D
I have not followed up on this because it is not an issue for me at prese=
=3D
nt. =3D20
=3D20
Also as everyone knows=3D2C slumping=3D2C fusing=3D2C and glass casting al=
l happ=3D
en at different temps and all require annealing for long term stability. =
=3D
=3D20
=3D20
Devitrification of the glass at pottery firing temps can cause sodium scumm=
=3D
ing cloudyness in/on the glass but in my experience it has not been a probl=
=3D
em when the glass is fired on and melted into a glaze pool. Which by the wa=
=3D
y=3D2C a new COE forms for the co-mingled finished product.
=3D20
=3D20
David Woof
=3D20
=3D20
2a. Re: mel's glass project
Posted by: "Snail Scott" claywork@FLYING-SNAIL.COM=3D20
Date: Sun Oct 11=3D2C 2009 8:32 pm ((PDT))
=3D20
On Oct 10=3D2C 2009=3D2C at 3:49 PM=3D2C Keith Arbogast wrote:
> There is a wonderful potter from Florida=3D2C Peter Streit=3D2C who puts
> colored glass in the bottom of bowls and the effect is stunning. I
> don't know the type of glass or the firing details=3D2C but I think he
> puts a solid piece of clear glass over the broken pieces of colored
> glass to make a smooth surface...
=3D20
=3D20
The 'cracked ice' effect is due to incompatible CoE
between the clay and glass=3D2C not the chunkiness
of the glass pieces. Putting more glass over it
would change nothing. Would it really be possible
to have a glaze with a CoE compatible with the
clay which wouldn't be also be cracked by the
stresses in the underlying glass? Seems unlikely.
The cracking=3D2C remember=3D2C happens in the lower
stages of cooling=3D2C after things haver solidified to
the point where they can't accommodate any
further dimensional changes. Any normally
non-crazing glaze or even a CoE-compatible
glass would probably be cracked by the forces
of the glass splitting up underneath it.
=3D20
Tommy Humphries mentioned annealing (controlled
slow cooling) to reduce cracking=3D2C but if cracking is
the look that's wanted=3D2C annealing won't help.
=3D20
A type of cracked-ice glaze is currently popular
in commercially-made ware=3D2C but it's a thin glaze=3D2C
well-bonded to the clay underneath=3D2C and a far cry
from the misfit of regular melted glass puddles.
=3D20
Is Peter Streit's glaze truly smooth on top=3D2C or are
the crazing lines just not very sharp or open?
Sometimes they aren't obvious=3D2C but are they truly
absent? Please tell more...
=3D20
-Snail
=3D20
=3D20
=3D20
=3D0A=3D
_________________________________________________________________=3D0A=3D
Your E-mail and More On-the-Go. Get Windows Live Hotmail Free.=3D0A=3D
http://clk.atdmt.com/GBL/go/171222985/direct/01/=3D
L TURNER on mon 12 oct 09
On Mon, Oct 12, 2009 at 9:27 AM, David Woof wrote:
> The local glass man told me that common window glass contains lead, (ohhh=
=3D
fear and dread) =3DA0but if this is factual information, we should be awar=
e.
The best online source for glass composition is:
http://glassproperties.com/glasses/
The lowest cost glass is soda-lime-glass and that is what window glass
is made from
typical composition:
Soda-lime glass composition (containers, float glass e.g. for windows), mol=
=3D
%
Typical container glass
Typical float glass
Approximate limits pct mole
SiO2 63-81
Al2O3 0-2
MgO 0-6
CaO 7-14
Li2O 0-2
Na2O 9-15
K2O 0-1.5
Fe2O3 0-0.6
Cr2O3 0-0.2
MnO2 0-0.2
Co3O4 0-0.1
TiO2 0-0.8
SO3 0-0.2
Se 0-0.1
=3D3D=3D3D=3D3D
Your local glass man appears to be wrong.
Regards,
L. Turner
The Woodlands, Tx
douglas fur on tue 13 oct 09
L TURNER's got the data right.
Its the low Al2O3 which alows the glass to flow wich causes the fit problem=
.
Pots have more Al2O3 and its in the glazes so they don't flow off the pot.
You could make it fit but that would end the crackle...
The Kyoto recipe I got from a friend was 85 % glass 15%ash
DRB
Seattle
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