Laura Freedman on fri 20 sep 96
I have been collecting glazes from clayart for a while and have tested
some. I would like to share my results with you. I used Standard Ceramic
112 with the speckles and 181 white. Fired to Cone 6.
Metallic Black from Sharon LaRocca-Miranda
I substituted copper black oxide for black iron oxide (didn't have
any.) The results were truly wonderful on both clays. A winner.Truly
metal like sheen.
**************************
Floating Red - From Sharon LaRocca-Miranda
Interesting glaze. I first dipped two sample tiles too heavily
so I then dipped again with another two tiles- a lighter application.
The heavier dipped was much nicer. I'm not sure what to call this- khaki
color base with red in spots and where it breaks over the ridges. The
lighter dipped which looked adequately dipped had very poor coverage.
Good color on both tiles that were heavily dipped.
***************
MATTE GREEN from Tom Buck
Very nice on the white 181. Not very good on 112 speckled. Kind of
muddy colored on 112. I am going to try this again and double dip. This
was to be a cone 5 glaze but I took it to cone 6. At least that's what
my kiln sitter says. If I put an opacified in would this be better on
the 112?
*****************
Bob Wicks Glossy - Beautiful bright glossy hard glaze on both. Put
oxides (iron, chrome and cobalt) underneath. Sharp.
*****************
Bob Wicks White - similar recipe as glossy - Bright white glossy on both
tiles.
*****************
Simple Clear - from Clayart via C.Russell - Good, simple. Not as glossy
as Wicks. Also put the oxides under and they came out nice and clear.
*****************
Turquoise from Tom Buck - Cone 5 fired to cone 6. I found this to be a
disappointment. I will try this again. Poor coverage. Probably my fault.
********************
I have identified the glazes with people to keep it straight in my own
mind. I don't know if these glazes originated with those people.
Lauras@epix.net
Diane Woloshyn on fri 18 jun 99
Want to send the following glazes to Alfred Labs for testing, but I don't
know what to have them tested for. The blue, I presume, would be cobalt and
the green, cobalt and chrome, but what about the others?
All of these are ^6 oxidation and have come off of Clayart at one time. I
will be glad to share the results with everyone when they come back and
Alfred will have the results to publish.
Thanks for any help.
Falls Creek Shino
Albany Slip 56.07
Gerstley Borate 18.69
Soda Feldspar 9.35
Silica 9.35
Lithium carb 6.54
Superpax 9.35
Tin Oxide 4.67
The Albany Slip Substitute
Red Art 72
Whiting 10
Soda Feldspar 8
Talc 5
EPK 5
SAFFIRE BLUE
EPK 25.5
Frit 3134 42.6
Custer Feldspar 25.5
Silica 15
Rutile 4.3
Cobalt Oxide 2.13
FLOATING GREEN
Nepheline syenite 30
Gerstley Borate 21
Whiting 8
EPK 10
Silica 31
KAKI
Lithium carb 10.5
Bone Ash 10.5
Nepheline syenite 61.5
EPK 17.5
Red Iron Oxide 10.5
Diane Florida Bird Lady
Joanne L. Van Bezooyen on sat 19 jun 99
what makes the floating green, green?
Diane Woloshyn wrote:
> ----------------------------Original message----------------------------
> Want to send the following glazes to Alfred Labs for testing, but I don't
> know what to have them tested for. The blue, I presume, would be cobalt and
> the green, cobalt and chrome, but what about the others?
>
> All of these are ^6 oxidation and have come off of Clayart at one time. I
> will be glad to share the results with everyone when they come back and
> Alfred will have the results to publish.
>
> Thanks for any help.
>
> Falls Creek Shino
>
> Albany Slip 56.07
> Gerstley Borate 18.69
> Soda Feldspar 9.35
> Silica 9.35
> Lithium carb 6.54
> Superpax 9.35
> Tin Oxide 4.67
>
> The Albany Slip Substitute
>
> Red Art 72
> Whiting 10
> Soda Feldspar 8
> Talc 5
> EPK 5
>
> SAFFIRE BLUE
>
> EPK 25.5
> Frit 3134 42.6
> Custer Feldspar 25.5
> Silica 15
> Rutile 4.3
> Cobalt Oxide 2.13
>
> FLOATING GREEN
>
> Nepheline syenite 30
> Gerstley Borate 21
> Whiting 8
> EPK 10
> Silica 31
>
> KAKI
>
> Lithium carb 10.5
> Bone Ash 10.5
> Nepheline syenite 61.5
> EPK 17.5
> Red Iron Oxide 10.5
>
> Diane Florida Bird Lady
John Hesselberth on sun 20 jun 99
Hi Diane,
It is great to see someone willing to test their glazes. Unfortunately,
very few are willing to do so. Please note that I have not looked at
these glazes' unity formulas and compared them to limits--I am only going
by what is in them and the potential of those materials to cause harm. I
would offer the following suggestions:
Falls Creek Shino: I would probably test for lithium and boron.
Everything else is pretty innocuous. Some would even say I was being too
cautious testing for those.
Albany Slip Substitute: I see no need to test this one.
Saffire Blue: I would test for cobalt and, maybe, boron.
Floating Green: You didn't show the chrome and cobalt concentrations,
but they should be tested for.
Kaki: I would test for lithium. It is at a higher level here than in
Falls Creek Shino so I would give this one priority if you only test one
for lithium
I tend to test more than most people would. If you are on a tight
budget I would set the priorities for the materials in this set of glazes
as follows: 1. chrome 2. cobalt 3. lithium and 4 boron.
For those you decide not to test at Alfred, do the vinegar and dishwasher
tests to be sure they will hold up in use. I'll be eager to hear your
results. John
Diane Woloshyn wrote:
>----------------------------Original message----------------------------
>Want to send the following glazes to Alfred Labs for testing, but I don't
>know what to have them tested for. The blue, I presume, would be cobalt and
>the green, cobalt and chrome, but what about the others?
>
>All of these are ^6 oxidation and have come off of Clayart at one time. I
>will be glad to share the results with everyone when they come back and
>Alfred will have the results to publish.
>
>Thanks for any help.
>
>Falls Creek Shino
>
>Albany Slip 56.07
>Gerstley Borate 18.69
>Soda Feldspar 9.35
>Silica 9.35
>Lithium carb 6.54
>Superpax 9.35
>Tin Oxide 4.67
>
>The Albany Slip Substitute
>
>Red Art 72
>Whiting 10
>Soda Feldspar 8
>Talc 5
>EPK 5
>
>
>SAFFIRE BLUE
>
>EPK 25.5
>Frit 3134 42.6
>Custer Feldspar 25.5
>Silica 15
>Rutile 4.3
>Cobalt Oxide 2.13
>
>FLOATING GREEN
>
>Nepheline syenite 30
>Gerstley Borate 21
>Whiting 8
>EPK 10
>Silica 31
>
>KAKI
>
>Lithium carb 10.5
>Bone Ash 10.5
>Nepheline syenite 61.5
>EPK 17.5
>Red Iron Oxide 10.5
>
>
>Diane Florida Bird Lady
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"It is time for potters to claim their proper field. Pottery in its pure
form relies neither on sculptural additions nor on pictorial decorations.
but on the counterpoint of form, design, colour, texture and the quality
of the material, all directed to a function." Michael Cardew in "Pioneer
Pottery"
Ron Roy on sun 20 jun 99
Hi Diane,
Good for you - I am interested in the results - please.
Would you please have the Shino and Kaki tested for lithium leaching - I'l
be glad to share costs.
RR
>----------------------------Original message----------------------------
>Want to send the following glazes to Alfred Labs for testing, but I don't
>know what to have them tested for. The blue, I presume, would be cobalt and
>the green, cobalt and chrome, but what about the others?
>
>All of these are ^6 oxidation and have come off of Clayart at one time. I
>will be glad to share the results with everyone when they come back and
>Alfred will have the results to publish.
>
>Thanks for any help.
>
>Falls Creek Shino
>
>Albany Slip 56.07
>Gerstley Borate 18.69
>Soda Feldspar 9.35
>Silica 9.35
>Lithium carb 6.54
>Superpax 9.35
>Tin Oxide 4.67
>
>The Albany Slip Substitute
>
>Red Art 72
>Whiting 10
>Soda Feldspar 8
>Talc 5
>EPK 5
>
>
>SAFFIRE BLUE
>
>EPK 25.5
>Frit 3134 42.6
>Custer Feldspar 25.5
>Silica 15
>Rutile 4.3
>Cobalt Oxide 2.13
>
>FLOATING GREEN
>
>Nepheline syenite 30
>Gerstley Borate 21
>Whiting 8
>EPK 10
>Silica 31
>
>KAKI
>
>Lithium carb 10.5
>Bone Ash 10.5
>Nepheline syenite 61.5
>EPK 17.5
>Red Iron Oxide 10.5
>
>
>Diane Florida Bird Lady
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
Diane Woloshyn on thu 26 aug 99
Does anyone have an email address or phone number for Aflred Analytical Lab?
I sent five glazes for testing, including a ^6 Shino, at the end of June. My
check to them cleared the bank on July 15. Still have not heard a word.
Need to check that results did not get lost in the mail. Sent an email to
John Hesselberth but it bounced back. Anyone? Thanks. You can reply off
list.
Diane Florida Bird Lady
cwolo@aol.com
Olivia T Cavy on fri 27 aug 99
Diane,
The address and telephone numbers you are looking for is:
Dr. Roland Hale
Alfred Analytical Laboratory
4964 Kenyon Road
Alfred Station, NY 14803
607-478-8074 or fax at 607-478-5324
I do not have an email address.
Bonnie
Bonnie D. Hellman, Pittsburgh, PA
PA work email: oliviatcavy@juno.com (NO attachments please to this
address)
PA home email: mou10man@sgi.net (that's the number 10 in the middle of
the letters)
Colorado email: mou10man@RMI.net (that's the number 10 in the middle of
the letters)
On Thu, 26 Aug 1999 12:09:30 EDT Diane Woloshyn writes:
>
> ----------------------------Original
> message----------------------------
> Does anyone have an email address or phone number for Aflred
> Analytical Lab?
> I sent five glazes for testing, including a ^6 Shino, at the end of
> June. My
> check to them cleared the bank on July 15. Still have not heard a
> word.
> Need to check that results did not get lost in the mail. Sent an
> email to
> John Hesselberth but it bounced back. Anyone? Thanks. You can
> reply off
> list.
>
> Diane Florida Bird Lady
> cwolo@aol.com
___________________________________________________________________
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Joan Walton on sat 4 nov 00
Hi! Another lurker steps out of the forest.
I’m about to embark on some heavy-duty glaze testing
and was intrigued by Paul Lewing’s remark “easily dip
them into the little mixer I use to make tests in.” I
would be very grateful for info on the mixer and the
method. Do you make 100gm. tests? To me that seems a
very small amount, prone to big fluctuations in the
results from making such small measurements. 300gms
seems better, plus you can continue to test glaze
combos with the leftovers. What do you think? Also,
when mixing these small batches with tiny quantities
such as 0.35% chrome oxide, does anyone have a secret
for accuracy other than a digital (big $) gram scale?
TIA to all who wish to respond, especially, hopefully,
Paul.
Joan in Brooklyn, NY
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Cindy Strnad on sun 5 nov 00
Hi, Paul.
I always mix 500 gram batches because I dip little bowls (usually tea bowls)
as test pieces, and not tiles. If you're dipping little tiles, 100 grams is
fine, but I like a bit more of a surface in order to evaluate the glazes
more thoroughly.
As you're new, here are a few tips.
Do screen your test glazes. It doesn't always make a lot of difference, but
sometimes it does. If you can't sieve them, at least let them sit a day or
two and re-mix before glazing anything with them. A hand-held immersion
blender works great and costs less than $10.
Digital scales aren't necessarily more expensive than a good triple beam. I
paid less than $100 for mine (I'm thinking around $75 or so, but I don't
remember). It weighs up to 1000 grams and is very accurate. (I tested with
the weight set I had for my old triple-beam.) Perfect for test batches and
even for weighing the more sensitive ingredients for large batches. A good
investment, and try getting a good triple-beam for less than that.
Round off anything behind the decimal point. If the recipe calls for 7.34%
rutile, it will be okay to just add 7%. Really, it will. I even round off
cobalt oxide. If it needs that tenth of a percent, it's way too picky of a
glaze for me. Besides, my scale only weighs in one gram increments.
Hope this is of help,
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Paul Lewing on sun 5 nov 00
Joan Walton wrote:
> I¹m about to embark on some heavy-duty glaze testing
> and was intrigued by Paul Lewing¹s remark ³easily dip
> them into the little mixer I use to make tests in.² I
> would be very grateful for info on the mixer and the
> method.
Hi, Joan.
The mixer I use is a little food chpper/blender that I believe is made
by Cuisinart. I got it at Costco a few years back after I wore out the
first one I had. I got that one by going to one of those time-share
condo pitch things where they promised a free food processor to anyone
who came. It was a joke as a food processor, but made a nice glaze test
mixer. It holds about 2 cups of liquid, and I have the beaker part
marked off with a magic marker where enough water for a 100g test comes,
so I can just put in the water and add ingredients as I weigh them out.
(Mark it in pencil and make a few tests to se if you have it in the
right place). I also have it marked off where a 100g batch of wet glaze
comes, so I can just put in that much of a base glaze and add colorants
or other ingredients. It's also marked off where 200g of wet glaze
comes to.
Do you make 100gm. tests? To me that seems a
> very small amount, prone to big fluctuations in the
> results from making such small measurements. 300gms
> seems better, plus you can continue to test glaze
> combos with the leftovers. What do you think?
I make 100g tests. Yes, they're pretty small, but you have to realize,
I may make 300 or 400 test tiles a year, from maybe 100 different
recipes. I generate enough scrap glaze as it is without making bigger
tests. If something looks real promising on a 100g test, I'll make 500g
next time, but 90% of your glaze tests won't be worth keeping, I'll
guarantee you. Even after all the testing I've done, I'd bet that over
half the tests I make go right in the scrap bucket. And you'd be
surprised how far off you can be on the measurement of most glaze
ingredients and not be able to tell any difference. Colorants are
usually an exception, but most base glaze ingredients, you can add or
subtract a whole gram or two in a 100g batch and not see a difference in
the fired result. These recipes that are carried out to two decimal
points are nonsense.
Also,
> when mixing these small batches with tiny quantities
> such as 0.35% chrome oxide, does anyone have a secret
> for accuracy other than a digital (big $) gram scale?
To weigh out less than a gram accurately, put a small piece of paper on
your scale, zero it out with the paper on it, weigh out one gram, then
separate it by eye with a knfe blade. About a third of one gram is
close enough to 0.35% for testing purposes. Just remember to put your
scale back to zero without the paper when you're done.
I once heard Lana Wilson say something really apt about glaze testing.
She said, "This is not marriage- this is coffee dating. We're just
trying to see if we're compatible here. We're not trying to see if we
want to live together forever."
Happy testing,
Paul Lewing
The Buchanans on mon 6 nov 00
Paul, a permanant coffee maker filter (they are sold to replace the paper
kind) is perfect for screening glaze and fits on a half pound margerine cup
which holds a hundred gram test easily.
I think it is important to screen after each coloring oxide addition for
smoother results.
When you need less than a gram of oxide for a test, measure out one gram on
a piece of paper. With a blade smooth it into a flattened square and half
it, then quarter it etc. Then scrape the needed amount onto another piece of
paper and dump it in. Of course you'll probably add another quarter gram and
screen again for another test and then another. :>) That's how you always
end up using 4 times the test tiles you expected to fire.
Judi B.
>
Do screen your test glazes. It doesn't always make a lot of difference, but
> sometimes it does. >
____________________________________________________________________________
__
>
will edwards on sun 17 dec 00
Hello,
Alisa is it good to know you are going to get a break. I thought you migh=
t
have gotten covered up in so much glaze by now you had turned to concrete=
=2E
(Smile)
I am about ready to run my first series of tests myself on these glazes a=
nd
will send them out as I get the results. =
Also for the one who lost their pottery I must also say I am sorry to hea=
r
this at this time of year. It isn't much of a way to kick off the holiday=
s but
good things will come to you!
Last>>>(Delete or read)
It does bug some of us here for certain when we see more energy put into =
a
thread about how to find something or where to look and then add a months=
worth of ad nauseum verbiage that insults one of the members directly and=
in
public without real merit! Why not do this off-list first? Seems to take =
your
time to add such offensive lip sevice here so why not just answer of dele=
te or
move on through the list?
Its no different when a manufacturer jumps on here whenever they see thei=
r
products mentioned in an unfavorable light and states this is as good a p=
lace
to settle this as any. (Is it really?)
Elizabeth has given much more than she has recieved I am sure. Also it is=
rather easy to get caught in the tense issues on occasion when some of th=
e
members are working out a solution between themselves that only they can
conclude. (Means it is not a thread you need to worry over)
Contributions come in varying shades of color.
Its a free service
The Web is full of other services
Check archives
(ARCHIVE) - Sometimes it does take a little doing but the archives is a g=
reat
place to roam around and you can learn so much there.
I apologize once more that I have elected to even bring anything negative=
back
up but I am getting so much help from the people on here that those who w=
ish
to argue over every tiny detail has cast a cloud over many of the topics =
at
hand. =
I also would like to firmly wish you all a very Happy Yule-Tide time of y=
ear
and that the spirit of giving and recieving is passed freely between all =
our
members here. Merry Chirstmas
William Edwards
____________________________________________________________________
Get free email and a permanent address at http://www.netaddress.com/?N=3D=
1
Pancioli on mon 19 feb 01
We use wet testing to explore color. Less hazardous and MUCH MUCH
faster.
It goes like this:
Weigh out 3000 grams (dry at first of course) of a recipe you would like
to test for color response.
Add water and seive.
Divide evenly (by eye or weight) into 6 similar containers.
Add percentages of six different colorants, one to each container, and
stir well.
Divide the contents of each container evenly into six small paper cups.
First put each of the six colored glazes on a tile (these are the base
line colors).
Then mix (by pouring together) each cup with every other cup: 1+2. 1+3,
1+4, 1+5, 1+6; 2+3, 2+4, 2+5, 2+6; 3+4, 3+5, 3+6; 4+5, 4+6, 5+6.
Mark the tiles.
You will all probably recognize this as a "50/50 blend". The only
difference from the way I learned it a long time ago is that it is
TEN times faster doing it wet, and equally informative.
Diana
Ron & Nancy on mon 12 mar 01
Richard,
I tried to get you off clay art ,but no dice. Tell your friend to go
to the Mexican Import store on Broadway and (about ) 6th st. (south/west
side of the street.) They have all their pottery tested, before selling
they can give you the information you are seeking.
Or write to me off clay art and ! can give you better information on
the directions, too late tonight to remember the name of the place.
hope this helps ,
Nancy
Jonathan Pennington on mon 24 dec 01
So with all this discussion about glazes, where can I get mine tested?
I'm assuming that Ron and John will have that in their book as well,
but until that's out, where are some fairly inexpensive labs where I
can test my glazes? Right now, I'm not selling, but when I give them
as gifts I use the "This glaze *should* be safe for food use, but it's
not been tested by a lab yet, I'll let you know if you want to wait to
use it" approach.
-J
--
Jonathan Pennington | jwpennin@bellsouth.net
"There are no pots, there is only clay." -original
"It's hard to take life too seriously
when you realize yours is a joke." -also original
John Hesselberth on thu 3 jan 02
on 12/24/01 2:43 PM, Jonathan Pennington at jwpennin@BELLSOUTH.NET wrote:
> So with all this discussion about glazes, where can I get mine tested?
Hi Jonathon,
There are only two labs I am aware of that leach test at prices that potters
can afford. One is Alfred Analytical Lab in Alfred Station, New York (not
associated with Alfred University) and the other is BSC in Kennett Square,
PA. Service at Alfred Analytical has gotten so uncertain that I now do
nearly all my testing at BSC. You can find the details at
http://www.frogpondpottery.com/glazetest.html
We devote a full chapter to testing glazes in the book. Most of the tests
are ones you can do right in your home or studio at essentially zero cost.
Regards,
John
Web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
Email: john@frogpondpottery.com
"The life so short, the craft so long to learn." Chaucer's translation of
Hippocrates, 5th cent. B.C.
Ellen Currans on sat 16 aug 03
I find that having an organized space to do glaze testing makes it much
easier to get to it. I have one wall with shelves in my glazing area which holds
all my glaze materials and tools. I'm short but I work standing up, so my gram
scale is on a wide shelf at the proper height to fill and read easily
without bending. There is room on the shelf to hold scoops, plastic containers,
file cards (one for each glaze to be tested). There is a good light directly
above the scale.
On shelves above this wider shelf I keep all my oxides, stains, additives,
etc. in pint to half gallon size plastic jars. Plastic, because I don't want
to even think about what a mess I'd have on the concrete floor if all those
expensive oxides in glass bottles came off the shelves in an earthquake. Salsa,
herbs, peanut butter, etc. come in suitable jars, tho I would have loved to
order matching jars from a chemical supply house.
Below the scale shelf are four shelves wide enough to hold gallon plastic
milk jugs two deep (I put the less used chemicals behind the more common ones)
which contain all my available glaze and clay materials. These are jugs with a
handle on the side and a large hole cut out of the top. Each is labeled in
large print on two sides. They fit under the shelf so that no lid is needed -
not much dust gets in them -and they are easy to pluck off the shelf with one
hand and scoop out the material without taking off a lid.
The jugs are refilled when needed from bags kept in an adjoining storeroom,
and I even use this system for mixing my usual glazes. A gallon jug will hold
enough of most materials to make a 10,000 gram batch. This sure beats
crawling under the tables and unstacking bags to get to the little bit of material
you need when mixing 100 gram tests. It is always convenient to weigh out
tests which can be held in plastic sandwich bags (labeled of course) until you
have time to do the actual mixing.
I started with a wall area four feet wide and later expanded to 7 feet.
I use a $3.50 Hamilton Beach Drink Master (from the thrift store) to mix
test batches and only need to sieve those with a few difficult ingrediants. I
fill a plastic jar about 1/3 full of water ( it came with vitamins in it and
holds about l cup full), add the dry ingrediants from the baggie, swirl around,
hold up under the mixer for a few minutes, and the glaze is mixed. Water is
adjusted as needed and remixed. Swish out the jar with a brush and you are
ready for the next test. Tests are saved in baby food jars, until I've decided if
they are useful or not.
Oh yes, keep good records, and there have been some excellent suggestions on
clay art. I love the carpet on the wall with velcro attached tiles! I need
another empty wall.
Ellen, from the warm, dry Willamette valley of Oregon. I doesn't rain here
all the time!
Paul Lewing on wed 18 jan 06
on 1/18/06 5:40 PM, Bobby Childs at bobby@TBLCRAFTS.COM wrote:
> I have recently started making glazes for my wife's pottery. I understand
> i should have my glazes tested to see if they are food safe. I am curious
> as to what metals I should test for other than the the obvious, Lead and
> Cadmium.
Bobby, if you're making the glazes, you must know what's in them. If
you're not adding any lead or cadmium, there's no point in testing for
those.
If you just want to see if your base, uncolored glazes are OK, make each of
them up with about 5% copper carbonate and have that tested. Copper is the
hardest thing to keep in a glaze. If it'll hold the copper in, it'll hold
anything.
Paul Lewing, Seattle
Bobby Childs on wed 18 jan 06
I have recently started making glazes for my wife's pottery. I understand
i should have my glazes tested to see if they are food safe. I am curious
as to what metals I should test for other than the the obvious, Lead and
Cadmium.
Any help or recommendations would be appreciated.
Bobby Childs,
TBL Crafts
bill edwards on fri 17 mar 06
I have a few contributions left here and there. Keep
in mind that I have no way of firing now and will
depend on those who ask questions to do the foot-work.
I will possibly be working off and on at Britt Davids
and if I am there I will be trying to introduce some
glazes which means I will have a minimal chance to do
testing but not the same controls I once held.
Fact is, I am mostly doing paper work, calculations
that are not exclusive to glazes but more so for other
art products. Testing sodium polyacrylates and various
flow properties and all that boring stuff. Now with
that said, I can see some new ways to enhance glazes
using some strange chemistry, inparticular some newer
methods for doing majolica using this old chemistry in
newer ways. I wish Linda Arbuckle would contact me
with a note saying she is interested in trying some of
this. (Perhaps she will read this and get bug biten) I
would love to see how to use coloring oxides in a
different way without the use of
Carboxylmethylcellulose and how effective these
changes may be under firing conditions. Yep - I
already know someone is going to tell me about fumes,
I understand this. All kiln fumes are toxic if you
stand there and breath them. This is no more of a
problem than the rest of the combustables in the kiln,
perhaps even less in some ways. Copper, zinc,
manganese and sulpher are but a few.
Trivalent Chromium - The fumes or residuals you can
see from chromium in the kiln for several firings that
tinge some white glazes pink. Not to be alarmed! At
least this is one you can visually see that volitizes
whereas lead and cadmium aren't as inviting but remain
a long time after the fires go out.
Here's a recipe for those who like to test glazes.
Here's why and how. The why? It will help you
understand how to get red from an otherwise green
glaze. It will also show you how vapors penetrate
bricks and remain settled till re-heated enough to
volitize and find romance once more with your whites.
Also for others who may have some of my earlier
recipes for this glaze, check your records and up-date
them to this.
Edwards Chrome Tin Red. ^6 ox. 03/17/06
F 3134 - 24.00
Neph Syen - 10.00
EPK - 16.00
Whiting - 20.00
Silica - 26.00
Talc - 2.50
G-200 Potash Spar - 1.50
Tin Ox - 5.00
Chromium Oxide - 0.40 +/- based on your tastes. I
would consider this the higher level, so going under
that would be wise to start if your testing for color
hue and vibrancy.
Now make the same glaze and leave out the chromium to
get a white. Place that in the kiln for several
firings. It is a low AL203 and low SiO2 glaze with
high CaO. Its a sodium glaze which I predict to be
soluble of course because I have done many tests using
similar bases. Whats the purpose? None other than for
your physical testing against other CTR out there.
Aesthetic use and decorative use. Now I can adjust
this and continue getting a red but this one was for a
more brighter version attempting to get as close to
copper red as possible. Here's something to note -
when it is first made, let it stand for about a week
or two before you use it. Put it on in 3 coats dipping
the first time about 1/2 inch from the bottom of the
piece and not doing a count down, just dip. add an
over-laying dip and then a drop about a 1/3 back up
towards the lip and dip it again so you have 3 very
distinct dip lines showing 1/3-1/3-1/3 with a margin
at the foot of the pot for good measure.
The molecular side of things. I will give you one, Ron
and perhaps a dozen or more will give you another
version. This is the differences in materials added to
the glaze base calculations tools. It often is close,
not perfect and is based on whatever companies
analysis is for that material at the time it was
introduced to your calculations data base. This is
where minor mistakes can go a long ways. Sometimes it
matters a whole lot sometimes not as much.
Seger Weight%
KNO 0.175 4.78%
CaO 0.771 18.06%
MgO 0.054 0.90%
Al2O3 0.229 9.74%
B2O3 0.215 6.25%
SiO2 2.376 59.58%
TiO2 0.002 0.07%
K2O 0.019 0.76%
Na2O 0.156 4.03%
Cr2O3 0.0071 0.45%
Al:Si 10.37
Expan. 9.78
ST 312.02
For those who will argue the vitues of this glaze will
need to post a picture of what they got, that is if
they follow procedure and often many will miss
something if not very careful. I still have some
pictures on CD of this glaze. Actually there was
several ladies where I was teaching at one time who
talked me into just mixing the white for some flower
pots and discovered they liked the pink so much the
red got left behind. But its a good way to examine two
things, where the volatiles go, how to get a brighter
red. You can't get there from here so you have to go
to your shop and start weighing up the samples. Have
fun!
Bill Edwards
http://apottersmark.blogspot.com/
'Studio Pottery Set-up for Sell, offers considered!'
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