Joyce Lee on sun 1 nov 98
Probably seems like overkill, but after mixing 100 and 200 gram tests
for some time, I felt I needed more information than I was getting from
these small test samples. I still use the 100g tests for line blends and
those six-section blends Robin Hopper describes in Ceramic Spectrum,
which ARE great for testing totally unknown glazes that may or may not
have any redeeming values for me. However, for a true test of every
aspect I can think of for a glaze that has either been recommended by
others or I've seen myself and admired and think it has a fighting
chance on my pots, I mix 2500 grams. I can then place small bowls or
largish tiles or small plates in all parts of the kiln, and am able to
try with wax, without wax, thick&thin applications, layered with other
glazes and on different clay bodies. Even so, the glazes sometimes turn
on me and react differently a few firings later. I'll NEVER make it to
glaze guru status since even with all this testing, my glazes tend to
have a mind of their own. Can glazes be anthropomorphic? I think so.
And NOW I hear from a most reliable source that the soda-ash in shinos
tends to travel to the outside along with the evaporating water so
saggar-firing probably won't help create the same warm toasty look on
the outside of a shinoed pot that it always has on the inside. Drat.
Joyce
In the Mojave thankful for all the Clayarters' responses and suggestions
to my last "firing" post. I am humbled.
Joseph Herbert on mon 2 nov 98
------------------
Joy Holdread wrote: =22Wear a mask =26 mix on large scraps of naoghhide sp =
makes
for easy clean up.=22
The wearing a mask is good but I wonder about the sheet of material for
mixing? Dry mixing of glaze ingredients is not necessary and probably is a
bad idea. Each measured material should be gently allowed to slide into a
standing amount of water. This minimizes dust. As a general rule, glazes
take a little more than an equal weight of water so for a 100 gram batch, a
half cup of water (125 grams) is a place to start.
Don=92t do dry mixing, the worst that can happen when placing the powders in
water is that you will have to wait and decant off some water.
A further observation from a training point of view. Knowledgeable persons
often omit basic information from their instructions. This assumed =
knowledge
is common to the instructor and unknown to the student. From this we get =
the
above sort of practices. I have seen others do dry mixing of glaze
ingredients and can only think it is an omission in their instruction that =
is
the cause. Next time you think that =22everyone knows that=22 you are =
wrong.
Relay all the pertinent information, that is want good training is all =
about.
Joseph Herbert
JJHerb=40aol.com
Joyce Lee on tue 3 nov 98
Joseph's post on glaze mixing demonstrates one of the reasons Clayart is
such a valuable tool. I stopped dry mixing my glazes sometime ago when
I noticed the little puffs of chemcial dust that floated up from the
container no matter how slowly I stirred. It was my first discovery that
glazing/firing isn't as much like cooking as I'd thought. However, I
still was never sure how much water to add either...probably one reason
my "small test samples" seemed too small. Funny, most books do not
mention the all-crucial step of adding water to a glaze. Actually, I
haven't found any that give this info. Joseph's suggestion to add "a
little more than equal weight" of water to glaze is a good place to
start. Are there other tips available for mixing/dipping glazes? Even
though I follow the guidelines of letting your fingernails do the
talking, I never am confident of one dip/two dip or more...and just how
long IS a dip, anyway? Bought a hydrometer awhile ago. Could never
make it work...dratted thing kept sinking to the bottom. Decided 5
gallons just wasn't enough to measure. During clayarter-bud Lynne
Antone's visit she tactfully mentioned that maybe it sunk so fast
because the glaze was too thin. Turns out the hydrometer was doing its
job. I just didn't understand the basics. The question of the moment
is: "How did I arrive at such an advanced age thinking I was sooo
smart???"
Joyce
In the Mojave recognizing once again that "just the basics" is almost
the WHOLE thing...the problem is to get basic enough.
Joyce
In the Mojave
Lois Ruben Aronow on thu 5 nov 98
------------------
On Tue, 3 Nov 1998 10:05:29 EST, Joyce Lee wrote:
=3E----------------------------Original message----------------------------
=3EJoseph's post on glaze mixing demonstrates one of the reasons Clayart is
=3Esuch a valuable tool. I stopped dry mixing my glazes sometime ago when
=3EI noticed the little puffs of chemcial dust that floated up from the
=3Econtainer no matter how slowly I stirred.
FWIW, I think dry mixing is pretty important. Especially if the
recipe calls for Bentonite, which, I find, turns gelatinous when water
hits it. If I do do a dry mix, there will be a big jello lump that's
really tough to work through.
To solve the dust problem, I do the dry mix at the chemical bench and
I wear my respirator and gloves until the chems are pretty well mixed
in with the water. I do my dry mix with a whisk (yes, one for
cooking) as it tends not to raise too much dust.
=3E Funny, most books do not mention the all-crucial step of adding
=3E water to a glaze. Actually, I haven't found any that give this info.
=3E Joseph's suggestion to add =22a little more than equal weight=22 of =
water
=3E to glaze is a good place to start. Are there other tips available for
=3E mixing/dipping glazes?
I let my wet chemicals sit overnight, sieving it the next day. This
lets the chemicals and water mix. I tend to get lumps and granules if
I sieve the same day and don't let the chemicals soak in the water.
=3EEven though I follow the guidelines of letting your fingernails do the
=3Etalking, I never am confident of one dip/two dip or more...and just how
=3Elong IS a dip, anyway?
Ain't that the truth.
John Hesselberth on sat 7 nov 98
In following this thread I notice that some people use the phrase "adding
water to the dry glaze". If you haven't tried slowly pouring your dry
glaze into the water, give it a try. There is a world of difference! I
weigh out each component and immediately pour it directly into the
measured amount of water I need. It is pretty well slaked by the time I
finish weighing out the last ingredient. Then a minute or two of
stirring and once or twice through an 80 mesh screen and the glaze is
ready to use. John Hesselberth
>----------------------------Original message----------------------------
>------------------
>On Tue, 3 Nov 1998 10:05:29 EST, Joyce Lee wrote:
>
>>----------------------------Original message----------------------------
>>Joseph's post on glaze mixing demonstrates one of the reasons Clayart is
>>such a valuable tool. I stopped dry mixing my glazes sometime ago when
>>I noticed the little puffs of chemcial dust that floated up from the
>>container no matter how slowly I stirred.
>
>FWIW, I think dry mixing is pretty important. Especially if the
>recipe calls for Bentonite, which, I find, turns gelatinous when water
>hits it. If I do do a dry mix, there will be a big jello lump that's
>really tough to work through.
>
>To solve the dust problem, I do the dry mix at the chemical bench and
>I wear my respirator and gloves until the chems are pretty well mixed
>in with the water. I do my dry mix with a whisk (yes, one for
>cooking) as it tends not to raise too much dust.
>
>> Funny, most books do not mention the all-crucial step of adding
>> water to a glaze. Actually, I haven't found any that give this info.
>> Joseph's suggestion to add "a little more than equal weight" of water
>> to glaze is a good place to start. Are there other tips available for
>> mixing/dipping glazes?
>
>I let my wet chemicals sit overnight, sieving it the next day. This
>lets the chemicals and water mix. I tend to get lumps and granules if
>I sieve the same day and don't let the chemicals soak in the water.
>
>>Even though I follow the guidelines of letting your fingernails do the
>>talking, I never am confident of one dip/two dip or more...and just how
>>long IS a dip, anyway?
>
>Ain't that the truth.
John Hesselberth
Frog Pond Pottery
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"The whole aim of practical politics is to keep the populace alarmed, and
hence clamorous to be led to safety, by menacing it with an endless
series of hobgoblins, all of them imaginary." H.L. Mencken, 1925
Winnie Coggins on sun 8 nov 98
One method to dry mix without excessive dust is to weigh out materials and
place them in a large, heavy gage plastic bag (similar weight bag to what
commercially purchased clay is shipped in). Close the bag and then manipulate
it (shake, turn, massage) to get a mix of materials. Then pour slowly into a
bucket filled with approximately enough water to slake the mix. Proceed as
usual. For recyclers, mark the bag with the glaze name and use it again next
time you mix that glaze. This method works well with large (10,000 gram)
batches.
Winnie Coggins
Columbia, Maryland
Christine Dubois on mon 9 nov 98
How do you know how much water you will need? I've never seen a glaze recipe
that specified the amount of water.
Craig Martell on tue 10 nov 98
>------------------------Original message----------------------------
>How do you know how much water you will need? I've never seen a glaze
recipe
>that specified the amount of water.
Hi:
It's difficult to tell someone exactly how much water to add to any glaze
because different people will use different methods of application and will
want their glazes to be mixed to facilitate their way of working.
If you have a consistency that you like for any given receipe, you can mix a
500 gram batch and add water from a graduated cylinder or another type of
container that will tell the quantity of water added. Once you know how
much water you need for this amount, you can apply it to smaller or larger
amounts by just using simple math.
regards, Craig Martell in Oregon
Tom Buck on tue 10 nov 98
Christine Dubois:
Typically, your mix should have these densities (specific gravity,
but this term is deemed unacceptable by world chemists:
Spraying density: 1.45 grams per millilitre (kilograms per litre),
plus or minus 0.03 g/mL.
Dipping density, 1.55 g/mL (+/- 0.03 g/mL).
Brushing density, 1.65 g/mL or higher, depending.
To measure the density, take a plastic measuring cup of say 500 mL (2
cups (16 fl oz)), tare it (weigh it empty). Put in a known volume of the
glaze mixture ("slurry or slop"), say 200 mL and reweigh. You'd likely get
310 grams. This gives 300/200 or 1.55 g/mL.
Then you mix you glazes accordingly and get the slurry density
close to that needed by the application method you use. Then you fine tune
both the bisquing cone and the dipping time for best results.
Good tests.
Tom Buck ) tel: 905-389-2339 & snailmail: 373 East
43rd St. Hamilton ON L8T 3E1 Canada (westend Lake Ontario, province of
Ontario, Canada).
Caryl W. on wed 11 nov 98
>Date: Mon, 9 Nov 1998 09:08:54 EST
>Reply-To: Ceramic Arts Discussion List
>From: Christine Dubois
>Subject: Re: Glaze mixing
>To: CLAYART@LSV.UKY.EDU
>
>----------------------------Original
message----------------------------
>How do you know how much water you will need? I've never seen a glaze
recipe
>that specified the amount of water.
As a standard practice I add 90ml water/100gm.batch of glaze to be
mixed.So that's 900ml/1000gm.batch etc.etc.Just need to do the math.I
use a paint mixer on the end of a drill and add the dry chemical to the
water with a mix from the drill after each addition.I then screen at
least 4 times through an 80 mesh screen and let sit for a while( a day
or two if possible).Just before using I mix with the drill again, then
do the old finger test for thickness and add water at that point if
necessary.Some glazes seem to absorb a little water during the sitting
period, some don't, but I've never had to remove any water using that
formula.Hope this helps.
Caryl
______________________________________________________
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Rebecca Knight on fri 12 jul 02
And speaking of 5 gal. buckets, thanks to all who responded to my glaze
mixing questions last week. A few pointed out that I put 5 lb. instead of 5
gal. One of those cases of the brain thinking one thing and the fingers
typing something else.
I successfully mixed up larger batches of two glazes and did my third glaze
firing using these along with all of my smaller test batches of glazes.
Still trying to find the right temp and soak for my kiln so that I get
consistent firings. I fired ten degrees lower and soaked for 15 mins.
longer this time. For glaze firing 4, I will lower the temp another 10
degrees and add another 15 mins to soak.
Again, thanks for all the help.
_________________________________________________________________
Chat with friends online, try MSN Messenger: http://messenger.msn.com
Autumn Downey on sat 9 nov 02
These are the instructions specific to our Guild, (obviously using dry
mixing) if they are any help to anyone. Autumn
GLAZE MIXING (YK Guild)
Standard Guild Glazes are kept alphabetically in the Glaze binder.
Cautions: Wear a mask; try not to cause dust
Wear rubber gloves when handling wet or dry chemicals.
Do the mixing under fume hood with fan running.
1. Choose recipe and decide quantities. 4000 - 8000 grams make a bucket of
glaze. If you are doing a test, 100 grams is enough.
2. Put the measuring container on the scale and adjust the sliding weight
so that the scale is balanced. You do not want the weight of the pan to
count. A plastic ice cream bucket isn't too heavy and will hold large
amounts of material.
3. Weigh out each chemical and pour carefully into a large container. It
helps to mark each material off as weighed. Large quantities over 2500 g.
may be weighed in two parts.
4. Stir dry chemicals together slowly with whisk and without causing a
dust. Mixing up particle size prevents the glaze from being lumpy.
5. Two methods of mixing:
a. Add dry mix slowly to hot water. Let slake, then stir well. The amount
of water needed is usually about the same number of litres as there are kg
in the batch. i.e. 5000 g requires 5 litres. Best to start with less,
e.g. 4.5 litres and add the rest as needed/during rinsing of buckets.
b. Add very hot water to the dry chemicals; pour it down the side to
avoid making dust, stick a lid on and leave. Works well with most glazes if
they are dry mixed. Let mixture sit until bubbling has stopped; then
stir well.
6. Use talisman sieve (the white plastic one with the crank.) Sieve twice
with a coarse screen, adding water if needed. The consistency should be
about that of light cream. Add liquid gum solution at about 1/2 cup per
large batch and add more water if needed - gum changes the consistency.
(May not be needed with high clay glazes). Gum helps suspend the glaze,
and makes it stick better to bisqueware with a less powdery surface. N.B.
Glazes that become cement-like after sitting awhile are sometimes improved
by having 1-2 tbsp. of Epsoms salt solution added to them. Too much
Epsoms' salt makes the glaze like pudding.
7. Sieve twice more with a fine screen and put into large pail. Label
both pail and lid with glaze name. Also, attach a temporary note "not to
use the glaze till it is tested."
8. If a glaze that is new to the Guild, do tests on both red and white
clay, so there will be an indication of how it looks. If a standard
glaze, one test is enough. Label the test tile with underglaze pencil.
9. Update the Chemical Inventory book; (we keep a running total of
materials on hand so that supplies can be ordered.)
Kate Johnson on tue 4 jan 05
I'm interested in this thread as well, as I'm still exploring how to get an
approximation of an early traditional honey glaze without using lead. The
consensus is that adding red iron oxide to a transparent glaze is probably
as close as I can come, and I've found that to be true...it's not
satisfyingly rich, yet, but it is vaguely honey colored.
The problem is the specks of iron that remain in the fired glaze. I expect
and want SOME, but mixing, shaking, stirring, and multiple straining still
leaves more specks than seems acceptable. (MUCH better than my first
attempt, which resulted in the coarse ground pepper effect, but
still....) I got an 80-mesh strainer--need finer?
There's an example in the next to last photo on this page:
http://pg.photos.yahoo.com/ph/graphicartepsi/album?.dir=bbb8 (and by the way
the sgraffito owl plate that collapsed it next to it, on the left. Rats!
That outer rim is now touching the surface of whatever it's sitting on...)
If I brush the glaze on the iron specks smear in lines--if I pour it, I have
more, though smaller, specks than I want. It's almost as if it needs
crushing in a mortar and pestle when wet...now THERE would be a
time-consuming process!
Ideas? Suggestions, please? Wasn't sure what search terms to use on the
website, but didn't get specifics on this...
Best--
Kate
wjskw@BELLSOUTH.NET on tue 4 jan 05
Kate:
This might be a stupid question, but have you tried putting the DRY
ingredients through a blender cycle? It's time consuming (mostly
waiting for the dust to settle before opening the jar again) but it
will reduce everything to much finer particles. I find that a few
minutes on "high" (with the blender tipped as needed to keep
everything moving) lets the final mix pass through a 120 sieve.
If you can't get the powder to mix acceptably dry, you can always
add some part of your glaze water to it. Leave it going a while
longer then. Something you might want to play with. Used blenders
can be had for as little as $5 at a yard/tag/garage sale.
Best Regards,
Wayne Seidl
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Kate
Johnson
Sent: Tuesday, January 04, 2005 12:23 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Glaze mixing
I'm interested in this thread as well, as I'm still exploring how to
get an
approximation of an early traditional honey glaze without using
lead. The
consensus is that adding red iron oxide to a transparent glaze is
probably
as close as I can come, and I've found that to be true...it's not
satisfyingly rich, yet, but it is vaguely honey colored.
The problem is the specks of iron that remain in the fired glaze. I
expect
and want SOME, but mixing, shaking, stirring, and multiple straining
still
leaves more specks than seems acceptable. (MUCH better than my
first
attempt, which resulted in the coarse ground pepper effect, but
still....) I got an 80-mesh strainer--need finer?
There's an example in the next to last photo on this page:
http://pg.photos.yahoo.com/ph/graphicartepsi/album?.dir=3Dbbb8 (and by
the way
the sgraffito owl plate that collapsed it next to it, on the left.
Rats!
That outer rim is now touching the surface of whatever it's sitting
on...)
If I brush the glaze on the iron specks smear in lines--if I pour
it, I have
more, though smaller, specks than I want. It's almost as if it
needs
crushing in a mortar and pestle when wet...now THERE would be a
time-consuming process!
Ideas? Suggestions, please? Wasn't sure what search terms to use
on the
website, but didn't get specifics on this...
Best--
Kate
____________________________________________________________________
__________
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Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
claybair on wed 5 jan 05
Kate,
I use a 100 or 120 mesh to strain my slip which contains various iron
oxides. I think using a higher mesh will fix your glaze speckling problem.
Gayle Bair
Bainbridge Island, WA
http://claybair.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Kate Johnson
Sent: Tuesday, January 04, 2005 10:23 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Glaze mixing
I'm interested in this thread as well, as I'm still exploring how to get an
approximation of an early traditional honey glaze without using lead. The
consensus is that adding red iron oxide to a transparent glaze is probably
as close as I can come, and I've found that to be true...it's not
satisfyingly rich, yet, but it is vaguely honey colored.
The problem is the specks of iron that remain in the fired glaze. I expect
and want SOME, but mixing, shaking, stirring, and multiple straining still
leaves more specks than seems acceptable. (MUCH better than my first
attempt, which resulted in the coarse ground pepper effect, but
still....) I got an 80-mesh strainer--need finer?
There's an example in the next to last photo on this page:
http://pg.photos.yahoo.com/ph/graphicartepsi/album?.dir=bbb8 (and by the way
the sgraffito owl plate that collapsed it next to it, on the left. Rats!
That outer rim is now touching the surface of whatever it's sitting on...)
If I brush the glaze on the iron specks smear in lines--if I pour it, I have
more, though smaller, specks than I want. It's almost as if it needs
crushing in a mortar and pestle when wet...now THERE would be a
time-consuming process!
Ideas? Suggestions, please? Wasn't sure what search terms to use on the
website, but didn't get specifics on this...
Best--
Kate
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
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Ivor and Olive Lewis on wed 5 jan 05
Dear Kate Johnson,
I seem to be well out of step with the rest of the tribe with this
one. I could never get the traditional Honey glaze, that is a
transparent moderate golden orange yellow with Iron oxide.
But I do achieve this robust traditional style of finish with a
stoneware glaze based on Soda Felspar/Whiting and reasonable amounts
of Manganese Carbonate, round about twelve percent on a white clay.
Great colour, bright surface, fully transparent at cone 8 down.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
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