Paul Haigh on tue 8 apr 08
1) I love that whole nuka over other glaze thing. However- the nuka that I want to use (1:1:1 wood ash, silica, feldspar) is really flux saturated and high Si:Al (over 14). I know it won't leach anything dangerous out- but will it withstand the dishwasher etc for years? Should I limit it to not-as-food-functional wares? (firing to cone 11-12 in woodfire)
2) I have a question about spodumene in shino.
I have thus far avoided any copper, barium, lead, chrome, etc in any glazes. This is as much for sanitary/environmental reasons as it is about glaze safety for me. I clean a glaze bucket, or screen, or whatever out and the rinse water goes on the lawn- no worries about clogging my drain or poisoning my grass (my sandy soil can use the clay content). I wouldn't want any of that in my septic anyway. This is a "I don't have to worry" maneuver, rather than a misguided concept that they cannot be used safely- so let's not go there.
I understand that spodumene is meant to act as a flux and to control expansion, but I have some reservation about introducing Li into my glaze pallet. Are inhalation and acute poisoning the only issues? Any environmental concern?
Steve Slatin on tue 8 apr 08
Paul --
Remember, you can avoid food-contact surfaces even on
functional ware. The outside of a bowl is a great place
for out-of-whack effects; it can look great, offer tactile
feedback, and have zero risk exposure.
I'd be more concerned with the possibility of deterioration
in the glaze itself if exposed to heat/water/soluble
alkalis simultaneously, as is the case in a
dishwasher.
I hate to return to this particular soapbox, but if you
have doubts, the wise thing is to make a piece and
use it heavily -- expose it to metal marking, scratching,
acid attack, alkali attack, sudden temperature shifts --
and examine it closely (a loupe really does help) to
see what happens.
As far as environmental issues and lithium, I can only
note that lithium is widespread in the natural environment.
Tiny amounts can be found in many locations, but
elemental lithium is so reactive that it tends to create
tight bonds quickly -- did you ever see the sodium
metal in water experiment in a chemistry class?
(Kids, don't try this at home ...)
A chunk of lithium metal, dropped in your hand,
will burn right through your skin. Lithium carbonate,
spodumene, and similar materials just sit in the
palm of your hand, pretty close to inert. (Inhaling
dust is generally the most serious risk.)
Best wishes -- perhaps someone with more information
can help more -- Steve Slatin
Paul Haigh wrote:
1) I love that whole nuka over other glaze thing. However- the nuka that I want to use (1:1:1 wood ash, silica, feldspar) is really flux saturated and high Si:Al (over 14). I know it won't leach anything dangerous out- but will it withstand the dishwasher etc for years? Should I limit it to not-as-food-functional wares? (firing to cone 11-12 in woodfire)
2) I have a question about spodumene in shino.
I have thus far avoided any copper, barium, lead, chrome, etc in any glazes. This is as much for sanitary/environmental reasons as it is about glaze safety for me. I clean a glaze bucket, or screen, or whatever out and the rinse water goes on the lawn- no worries about clogging my drain or poisoning my grass (my sandy soil can use the clay content). I wouldn't want any of that in my septic anyway. This is a "I don't have to worry" maneuver, rather than a misguided concept that they cannot be used safely- so let's not go there.
I understand that spodumene is meant to act as a flux and to control expansion, but I have some reservation about introducing Li into my glaze pallet. Are inhalation and acute poisoning the only issues? Any environmental concern?
______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
---------------------------------
You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.
Hank Murrow on tue 8 apr 08
On Apr 8, 2008, at 10:50 AM, Paul Haigh wrote:
>
> 2) I have a question about spodumene in shino.
>
> I have thus far avoided any copper, barium, lead, chrome, etc in
> any glazes. This is as much for sanitary/environmental reasons as
> it is about glaze safety for me. I clean a glaze bucket, or
> screen, or whatever out and the rinse water goes on the lawn- no
> worries about clogging my drain or poisoning my grass (my sandy
> soil can use the clay content). I wouldn't want any of that in my
> septic anyway. This is a "I don't have to worry" maneuver, rather
> than a misguided concept that they cannot be used safely- so let's
> not go there.
>
> I understand that spodumene is meant to act as a flux and to
> control expansion, but I have some reservation about introducing Li
> into my glaze pallet. Are inhalation and acute poisoning the only
> issues? Any environmental concern?
None to my knowledge. Spodumene is a rock/mineral and the Lithium is
completely tied up at the molecular level with alumina and silica.
Cheers, Hank Murrow
Lee on tue 8 apr 08
On Tue, Apr 8, 2008 at 12:50 PM, Paul Haigh wrote:
> 1) I love that whole nuka over other glaze thing. However- the nuka that I want to use (1:1:1 wood ash, silica, feldspar) is really flux saturated and high Si:Al (over 14).
Hard to say Paul. I have some pieces I made almost 20 years
ago and they look fine. I have some old mashiko pieces that are very
old. The nuka doesn't seet in a dishwasher.
If you are worried, use a fake nuka with tin or zircopax
instead of saturated silica white.
> 2) I have a question about spodumene in shino.
I think Hank is right. But if you are worried, do one of the
gazillion shinos that doesn't contain spodumene.
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/
"All that is necessary for evil to succeed is that good men do
nothing." --Edmund Burke
Paul Haigh on wed 9 apr 08
Steve- Thanks! that's all I'm worried about is deterioration with nuka- not any leaching (there's nothing to leach). My firing cycle is so slow with the size of my kiln that it would be 7-8 months before I got any useful data, so I'm really looking for some first hand nuka experience before I start. If I don't nail it, then it will be years before I get the glaze I want :(
Nuka. I just like saying it.
As for lithium- ya, I've burned lithium, and sodium. It's reactivity is not my concern as much as environmental fate. Lead, and uranium compounds will just sit in your hand and are found widespread in nature- but I don't want to dump them on my property, and thus my question. (an aside- don't you love it when people tell you "it's all natural!"? I always reply- "So is rattlesnake poison and falling off a cliff- what's your point?" :)
Hank- thanks- and for the email. You've been a great help. My worry with it even in mineral state, some of this stuff breaks down in our acidic soil- especially well ground with all that surface area. Once it's out of the mineral, it's pretty mobile. I'm no major scale potter that would dump pounds in a year, so my concern may be quite overblown.
Lee- I did have some success with a faux nuka, but I just want to simplify with materials that I always have. In fact, I used the Rogers one at your recomendation and it was great, except in high ash-attack and serious flame blast areas of the kiln. I tried to get it a bit more resistant, but over did it.
3 part glaze- very cool. Thinking about a cheap ball mill and this would be a super easy glaze to make with local materials. I'll be looking at ash and a local clay when the ground thaws.
Lee on wed 9 apr 08
On Wed, Apr 9, 2008 at 7:20 AM, Paul Haigh wrote:
> Lee- I did have some success with a faux nuka, but I just want to simplify with
>materials that I always have. In fact, I used the Rogers one at your
recomendation
>and it was great, except in high ash-attack and serious flame blast
areas of the kiln.
> I tried to get it a bit more resistant, but over did it.
When you use traditional glazes, you can get a lot of technical
information by examining how the traditional potters used them.
Traditionally, Mashiko glazes are cone 8. Mashiko Kaki was used as a
liner glaze because it will seal a pot that is a little underfired.
Tradtionally, nuka, nuka seiji were used to decorate the
outside of pots, over a standard ash glaze.
>
> 3 part glaze- very cool. Thinking about a cheap ball mill and this would be a super >easy glaze to make with local materials. I'll be looking at ash and a local clay when >the ground thaws.
A bunch of folks on Woodkiln@googlegroups.com order from the now
defunct BigSky, rock crushers that work really well. Craig Edwards
got one and let it to me with a big sack of Custer rocks and it is
really fun turning stone into little pieces. You can control the
size of the particle through adjusting the plates and running the
crush through multiple times. I crushed granite too, from Craig's
garden and it makes a nice speckle effect as a clay inclusion.
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/
"All that is necessary for evil to succeed is that good men do
nothing." --Edmund Burke
Ron Roy on sun 13 apr 08
Hi Paul,
Hard to tell because there is no analysis for the ash - best to have it
tested if you need to know. Add 5% copper carb and 6 rutile and have it
leach tested for copper.
I'm not concerned about the lithium tied up in a feldspar like material
like spodumene. If you really want to know how stable a shino is - have it
tested - I don't think it's been done yet - anyone?
RR
>1) I love that whole nuka over other glaze thing. However- the nuka that
>I want to use (1:1:1 wood ash, silica, feldspar) is really flux saturated
>and high Si:Al (over 14). I know it won't leach anything dangerous out-
>but will it withstand the dishwasher etc for years? Should I limit it to
>not-as-food-functional wares? (firing to cone 11-12 in woodfire)
>
>2) I have a question about spodumene in shino.
>
>I have thus far avoided any copper, barium, lead, chrome, etc in any
>glazes. This is as much for sanitary/environmental reasons as it is about
>glaze safety for me. I clean a glaze bucket, or screen, or whatever out
>and the rinse water goes on the lawn- no worries about clogging my drain
>or poisoning my grass (my sandy soil can use the clay content). I
>wouldn't want any of that in my septic anyway. This is a "I don't have to
>worry" maneuver, rather than a misguided concept that they cannot be used
>safely- so let's not go there.
>
>I understand that spodumene is meant to act as a flux and to control
>expansion, but I have some reservation about introducing Li into my glaze
>pallet. Are inhalation and acute poisoning the only issues? Any
>environmental concern?
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
| |
|
