Kizzy on tue 27 jul 99
Hi Cindi...you wrote
I was also told my my clay supplier that low fire clays are lousy
> to throw with, and most catalog descriptions of low fire clays say for
> handbuilding.
That's an odd statement, pretty broad too..
> I would like to try a variety of low fire clay bodies (white, red,
> brown), so if you have favorite low fire clays what are they, and do you
> use it for handbuilding or throwing?
Currently I'm playing with Darcy's RdArt w/mica, ^06 can be fired to ^05,
begins to warp at ^04. I really like it.
One of my coleagues uses it for majolica, but I like it as is, for
flowerpots, runestones, spirit pots, urns, it has great green strength
Wheel work or slabwork, altho I don't do much of the latter. It's available
from Tacoma Clay, but our clay/tool supplier stocks a pretty good variety.
Hope this helps
Kizzy
Anji Henderson on tue 27 jul 99
I have used Campbell's LF white, brown, and red, for throwing and hand
building. I actually prefer it for hand building, but I have found that the
clays seem "Butterier" I have to consciously throw slower. And maybe it is
just me or maybe the clay, but I found that it chips easier. I have heard
others in my area complain that the outer layers disintegrate when left out
doors, with in a year (this is including taking it indoors for the winter).
>From my time with it I have tried to keep stuff that may end up out side HF
and use the LF for the rest. I haven't had any firing problems except the
Campbell's LF clear glaze bubbles.. That's a whole nother story..
Hope this helped in some way
Anji
Ron Roy on wed 28 jul 99
Mulite is what makes stoneware clays stronger than earthenware clays - so
firing stoneware clays lower than 1100C simply turns them into lowfired
clays (earthenware.) The will still leak and absorb water and still be
unfit for microwaving - and even doutfull for ovenware.
Hi talc bodies ( like 50 to 60%) are best for earthenware because they
resist water absorption - the kind that rehydrates clay and causes it to
expand and craze the glaze. There is also some enstatite developed in these
bodies which raises the expansion (and contraction) that helps with the all
too common crazing problems on earthenware. There is also a small amount of
cristobalite produces in high talc bodies - at temperature below 1100C -
which again raised COE and helps counteract crazing. Best to do some fit
testing of your glazes before you start changing bodies - those glaze that
do do immediatly craze now might just be pot busters on a body with a high
COE.
R
>----------------------------Original message----------------------------
>ORIGINAL POST:
>
>I've been throwing stoneware clays, but find myself firing them with low
>fire glazes often. Mainly I wanted to concentrate on other things
>before I started mixing my own glazes, and commercial glazes are low to
>mid range. I like some of the cool colors in low fire.
>
>Although I have been told that underfired stoneware is stronger than
>vitrified low fire clay, I have become convinced through ClayArt that
>this is not true. I should use a low fire clay if I'm going to fire it
>low. I was also told my my clay supplier that low fire clays are lousy
>to throw with, and most catalog descriptions of low fire clays say for
>handbuilding. But I just tried a bag of San Jose White from Claymaker
>and it seemed fine for throwing. (Maybe I'm missing something and it
>will all fall apart in firing???)
>
>I would like to try a variety of low fire clay bodies (white, red,
>brown), so if you have favorite low fire clays what are they, and do you
>use it for handbuilding or throwing?
>
>Thanks!
>
>ps If people email me directly, 'll collect the answers and send them
>all back out for you and the archives.
>-------------------------------------------------
>
>RESPONSES:
>Hi Cindi,
>I'm a handbuilder, and I use Carolina Buff from Campbell Ceramic Supply
>(Richmond Virginia). It's a great ( for me) white low fire clay, I've
>tried
>others and have always come back to it. Also it would seem ,from the
>list,
>that while some of the other clay companies have changes in quality and
>questionable customer service ,in 8 years I've never had a problem with
>Campbells.
>I hope this is helpful to you.
>Liz
>Bedford, Va
>
>Hi Cindi: I have been using Standard Clay Mines earthenware S105 with
>good results. I tried to send a scanned
>photo of what I do with it, I hope it gets to you. Decoration is done
>with commercial underglazes (duncan
>EZStrokes) right on the green ware, bisque to ^04 and glaze to ^06. All
>my pieces are thrown on the wheel, glazed
>all over and stilted on the bottom so they are waterproof. The bare clay
>will absorb water on a functional piece
>and weaken it in time. I hope this helps, let me know if you need more
>info. Carol Seidman
>
>Hello Emily Meunsch
>I often throw with very commonly found, super plastic clay here in
>Denmark
>called "blue clay". Bluish when wet, but despite it's name, it fires to
>cone 04
>a very pale orange terracotta . I routinely set my pots up on a turn
>table or
>wheel head and brush them with a white slip that of course fits the clay
>type.
>Big rabbit hair brushes. The brush strokes in the slip (medium thick
>viscosity)
>give an attractive and rustic whitewashed effect under transparent
>glaze. Pots
>are always leather hard or a bit wetter. Pots can be dipped also, (do
>NOT try
>this with completly dry, green post, they will crack up to pieces when
>slips
>starts to dry due to slip drawing too much on dry wall) but surface
>becomes a
>smooth white without any markings. This slip brushing works just as well
>on
>darker terracotta like common red clay. The stipes in the slip make a
>nice play
>of patterns under glaze or under further slip details painted over the
>white
>background.
>Alisa in Denmark
>
>Dear Cindi
>I use low fire white clay (mature at cone 02) most often. My favorite is
>Sandy Bottoms from Highwater Clays in Asheville NC. I only
>handbuild--don't
>know how it would hold up for throwing. Has a lot of grog. I also use a
>low
>fire red clay (matures at cone 02 also) from Highwater which is called
>buff
>eathernware, but it does come out more red than buff. Again, I only
>handbuild.
>
>I also use a mid-fire clay at lot--a buff that fires to cone 6. I use
>low
>fire glazes and colors all the time. Have never used glazes/underglazes
>that
>fire higher than cone 04. What I do is fire the cone 6 clay to cone 6 in
>the
>bisque firing and then fire to the cone of the glaze or underglaze in
>the
>next firing. The only problem there is not being able to apply a low
>fire
>underglaze to greenware if it is cone 6. Sometimes that presents me with
>having to fire more than twice.
>Hope this helps. Janice in NC
>
>Cindi,
> I have used S101 from Standard for over 10 years, which is rated
>from
>^02-9. I use it for hand building, throwing, high fire , low fire and
>Raku.
>I find it holds up better in raku than raku clay. I bisque everything to
>^02.
> Elizabeth Jacobs
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
Judy Frederick on fri 30 jul 99
In your post, you say that low fire clays are unfit for microwave and
conventional ovens. I was taught that as long as the clay was vitrified that
it was oven and microwave safe. I was also told to do a microwave test,
putting water into the vessel and running the microwave for 5 minutes on
high. Also run pieces through the dishwasher was another routine test that
should be done. I make a few mugs and small to medium dishes for dips or
soups, etc.
Judy in Baltimore
beginning ... the more I get into this the more confused I get
...............
*** The more you know, the more you forget,
*** The more you forget, the less you know,
*** The less you know, the less you forget,
*** The less you forget, the more you know! ! !
Tony Hansen on sun 15 aug 99
> I was also told my my clay supplier that low fire clays are lousy
> to throw with, and most catalog descriptions of low fire clays say for
> handbuilding. But I just tried a bag of San Jose White from Claymaker
> and it seemed fine for throwing.
> I would like to try a variety of low fire clay bodies (white, red,
> brown), so if you have favorite low fire clays what are they, and do you
> use it for handbuilding or throwing?
You are right. Low fire clays can easily be as good or better workability
than stonewares. Redart is a classic low fire red raw material. Manufacturers
can add ball clay to make very plastic bodies. Even 50% redart in a recipe still
fires quite red. Again, that leaves lots of room for plastic materials.
--
T o n y H a n s e n thansen@digitalfire.com
Don't fight the dragon alone http://digitalfire.com
Calculation/Database Software for Ceramic Industry
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