Clayphil on mon 6 oct 97
Hi all,
I am testing a batch of slop glaze, odds and ends of glaze accumulated over
time. As I anticipate this stuff will run off the pots or not mature
properly, I was wondering about stratagies to cope with these and other
faults? Add clay to lower the melting temp? And how do you guesstimate how
much to add to 4 gals of slop? It may not be pretty but I have alot of it; a
shame to throw it out.
TIA, Phil in Chicago
Ric Swenson on tue 7 oct 97
>----------------------------Original message----------------------------
>Hi all,
>I am testing a batch of slop glaze, odds and ends of glaze accumulated over
> time. As I anticipate this stuff will run off the pots or not mature
> properly, I was wondering about stratagies to cope with these and other
> faults? Add clay to lower the melting temp? And how do you guesstimate how
> much to add to 4 gals of slop? It may not be pretty but I have alot of
>it; a
> shame to throw it out.
>TIA, Phil in Chicago
You have the right idea in trying to re-use/re-cycle the left over glazes
In my experience, I have usually been surprised at how well the glaze
works...as is. IF you have a LOT of one glaze involved, it may resemble
that color more than anything else.....ie..if you dump in a LOT of
opacified (Titanium Dioxide rich) glaze...the result might be more "cloudy"
or satin than the batch that has little opacification available...
First of all....mix the stuff well and test it as is.
dip the top of a cylinder, down a few inches...then double dip a half inch
at the rim...
fire at the temp you normally use. (You might want to put a bisque fired
plate or bowl under the test...just in case it does a real meltdown
scenario. )
and ...when you see the result..the color/texture will suggest a name.....(
"slop" glaze...does NOT sound attractive...at all. ! ) 'Phoenix Eye', or
'Grade A Gray Day', or some equally clever name you associate with that
batch of left-over glazes.
Don't get attached to it...it won't last forever...and do NOT make a set of
dishes for someone using that glaze....if they ever wanted a replacement
piece, it would be hard to explain to them that their dishes were glazed
with an un-repeatable "slop" glaze. eh?
As with all materials, be aware of the hazardous materials in the primary
(your exposure to dust, etc.) and the secondary exposure (leaching in
acidic conditions by end-user...like the dangers of orange juice stored in
the lead glazed pitcher, et al..)
The addition of clay to 'raise' the firing temp. ( EPK has a melting temp.,
PCE, around cone 30, by itself? ) The addition of clay starting at 5% up
to 10 % might help if the glaze is really runny. If it is dry and not
'glaze like' (unlikely, I think.) try Neph. Sy. at 5-10 % Nepheline
Syenite (from Nepheline, Canada, I believe...?)
It is likely that the glaze will be one that crazes...balancing the
silica...and/or..using thin application techniques might help with that
process....
It will be an interesting project for you. Always "write down what you
did" and "only change one thing at a time"...or you won't really learn
anything for next time.
HTH
just my thoughts on a very beautiful, sunny and colorful Fall day in
Bennington, Vermont.
Ric
#################################################################
From: Ric Swenson, ( home ) : P.O. Box 494, North Bennington, VT
05257 - 0494
( work ) : Bennington College, Route 67 - A, Bennington, Vermont
05201 - 6001. ( 802 ) 440 - 4621 ( fax
440 - 4582 )
email: rswenson@bennington.edu
##################################################################
"If you teach a bear to dance,
..... you should be prepared to dance until the bear gets tired."
Louis Katz on tue 7 oct 97
From my column in the NCECA journal,
Dear Doctor,
Our glaze area sink does not have a trap, so we have been washing brushes,
buckets and other glazing tools in trash cans filled with water. The second
can is almost filled. I would hate to throw away this material. What should
I do?
Sincerely,
To the Rim in Arizona,
Dear Oops and Rim,
I applaud your desire to conserve resources, protect the environment, save
money and avoid violating the first principle (never throw anything away ).
My first experience with recycled glaze ingredients was when my job was to
empty a fifteen gallon trap built into the floor at the University of
Michigan in 5734 (1974). This material without any alterations was an
acceptable cone ten semi-matte black. If I remember correctly we called it
Scrap Black. It was not very popular, it might still be there..
My next experience was while my wife was teaching at University of
Missouri, Columbia. We had inherited a good deal of glaze remnants with
little documentation and a five gallon trap full of glaze material. We
mixed it all together and developed a few glazes with these materials.
Named "Moonlight over Montana" and other colorful names these firing
sensitive glazes with complexly colored and surfaces were studio favorites
until they ran out.
In the Island University studio I segregate the clay washing sink from the
glaze sink. This limits the variation in the scrap and insures that the
glaze scrap will at least come close to melting. It also limites the amount
of red clay in the scrap and keeps the scrap glaze from always being a
tenmoku. It is a good idea when possible to keep glaze scrap separated by
temperature. Since we fire most everything to cone 10 this is not a problem
for us.
When altering the glaze scrap I try to use only inexpensive ingredients,
and only those that are O.K. to dispose of in landfills. I mix and sieve
the scrap and test it in our normal firing cycle. If the scrap has chunks
in it that don't want to mix in I throw the chunks away.
Runny glazes that craze get additions of clay; sometimes a ball clay,
sometimes kaolin, occasionally a red clay. I use additions of about 2
pounds to five gallons. I don't bother weighing it. Glazes that craze but
are not runny get silica straight up or talc and silica. I use the talc
when I am short on matt glazes in the studio. Scrap that doesn't seem quite
melted usually gets whiting or dolomite, or occasionally plastic vitrox.
I favor red iron oxide, and rutile as colorants to add to scrap glazes. For
five gallons I use about 250 grams (1/4 pound). When the scrap glazes start
to build up however, some cobalt carbonate will increase usage. If the
glaze is not already too dark, cobalt carbonate 100 grams should make a big
difference in five gallons of glaze. With cobalt's cost, it better make a
difference. I usually prefer to use the big dollar colorants in tested
glazes.
A common fault of these scrap materials is over-floculation. This is often
caused by an excess of soluble ingredients in the scrap. Over-floculation
can cause crawling. To wash out the soluble salts, split the materials into
a few 1/4 full buckets. Add water until full, stir and let the scrap settle
out. Throw the water from the top of the buckets away. If the problem is
severe, wash the materials twice.
Scrap materials build up fast and fixing five gallon buckets has become too
much work. It seems that with good reclamation about 15 gallons of scrap
glaze appear semester down here at the Island University. I am beginning
this semester to fix the scrap glaze in 15 gallon quantities. We get the
buckets from community swimming pools. They get pool chemicals in them. The
buckets come with nice screw down plastic lids.
When a glaze looks especially nice, or I do a good demonstration pot with
it, it gets used quickly. The students know there will be no more. When I
am demonstrating glazing or onglaze decorating I often use an unpopular
scrap glaze, and wash the pot off afterward, so I can use the bisqueware
again.
Gail Busch, my wife, always washes her sigillata brushes in the same cup of
distilled water. Her scrap sig usually comes out a gray blue green.. Scrap
Raku glazes usually need no alteration,. and have been our most popular
surfaces. If they don't look good try adding copper carbonate.
The key to recycling is to spend you efforts where they will do the most
good. If a a batch of scrap just won't work, throw it away, and concentrate
your efforts more productively on a batch that looks promising. If a batch
looks like it will require a large alteration to make it work, throw it
away. Teach your students to use a spatula to recover glazes from pouring
containers and ladles.
Back to the studio.....,
Louis
Rick Sherman on tue 7 oct 97
------------------------original message-----------------------------
I am testing a batch of slop glaze, odds and ends of glaze accumulated
over time. As I anticipate this stuff will run off the pots or not
mature properly, I was wondering about stratagies to cope with these
and other faults? Add clay to lower the melting temp? And how do you
guesstimate how much to add to 4 gals of slop? It may not be pretty
but I have alot of it; a shame to throw it out.
TIA, Phil in Chicago
-------------------------------reply--------------------------------
Phil: I agree it is a shame to throw out and sometimes one gets an
exciting glaze and starts making pots for it. Don't adjust it until
you have run a test. Put some on a tile and place in or on a piece of
bisque in case it runs. I usually add EPK or silica or combinations
thereof. If too dry, I add whiting. Another trick is to use the slop
as one point of a tiaxial blend. Play with it. In the future, when
running glaze test or saving odds and ends. Have two buckets, one to
hold dark glazes and one for clear or light glazes. Most slops tend to
be dark and muddy.
RS
San Jose, CA
Leona Stonebridge Arthen on fri 10 oct 97
At 9:23 AM 10/6/97, Clayphil wrote:
>----------------------------Original message----------------------------
>Hi all,
>I am testing a batch of slop glaze, odds and ends of glaze accumulated over
> time. As I anticipate this stuff will run off the pots or not mature
> properly, I was wondering about stratagies to cope with these and other
> faults? Add clay to lower the melting temp? And how do you guesstimate how
> much to add to 4 gals of slop? It may not be pretty but I have alot of it; a
> shame to throw it out.
>TIA, Phil in Chicago
I've had some very good slop glazes. My favorite was "Sludge Green" which
turned out a semi matte green with darker spots. Given my production
methods, it didn't vary much from batch to batch. When I was working with
unfamiliar glazes, I washed up in a separate bucket till I knew what the
sludge would produce. If it was really yucky, I'd pour it into a bisqued
bowl and fire it solid before throwing it out!
Leona
In Western Mass. where the leaves are glowing with color.
---
Leona Stonebridge Arthen
leona@javanet.com
Worthington, Massachusetts/USA
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