Malone & Dean McRaine on tue 13 may 97
Aloha Amy,
Mixing by volume is much easier. However,since many (most) good high fire
glazes are finely balanced, sometimes complicated and some materials vary
slightly in density from batch to batch and some can be compressed there are
too many variables to be bang on accurate although simpler glazes will work
fine. Raku glazes are more forgiving and are often given in cup measure.
There is one source I've seen with high fire glazes by volume, I think it
was 'Glaze Projects' by Behrens published by Ceramics Monthly. Ask their
book service if I got it right before you buy. If you're going to make your
own glazes you're going to need a balance or digital scale. No springs.
Ohaus' are the standard but sometimes you can find good scales for cooking
that are work well for glazing and cheap, too. A company named 'Sohlne'
makes a great one, big pan, accurate, goes to 12 kg. I put a 5 gal bucket
on the scale tare off 1 kg. +/- to balance the bucket and measure all
ingredients right in.
Good Luck,
Dean
Lili Krakowski on tue 20 feb 07
"Gee whiz chucks, folks", quoth she, blushing shyly and kicking her toe
against a rock.
I did an article called "Measure for Measure" in PMI November 1999 (Vol
II, No 3) About measuring out glazes by volume.
PMI did not include the chart I had that showed what volume corresponded
to what weight. You are on your own.
There are different approaches to glazes by volume.
1. You take an educated guess and start mixing let us say 1/4c Neph Sy,
1/4c clay, with 1/4 c flint.
You test. You look at the result. You gasp! You scream! You think! You
then mix same mixture but add let us say 1/4 c whiting at THIS end and 1/4
c. dolomite at THAT end and do blends. Or you add more clay at this end and
more silica at the other. This is fun if you have an idea what you are
doing.
2. The method I started with. I simply weighed out a simple recipe, put
each ingredient separately in a baggie, then measured the contents of each
baggie. This gave me a basis for mixtures as above.
3. This one took a while to do. I measured out each ingredient I had in
my glaze pantry. I measured each in 1T . 1/8c, 1/4c and up.
I weighed the result. I repeated each measurement twice: First time I used
my measuring cup as scoop, leveled off with a knife blade, as in cooking.
The second time I ladled the materials into the cup, again leveling off.
The result with some materials was identical, with others not.
Likewise : 1/4 c. of X material did not necessarily weigh half of what 1/2
c of the material did. Either measuring cups ain't that accurate, or the
some materials pack down a lot.
I would suggest you do this on a day that is fairly dry. To do it at
monsoon time might make the measurements wrong--too much moisture.
I used only the cups that come in adorable little sets. NOT the big
measuring cups that are half pints and pints. I also used soda bottle caps
and detergent caps--be sure the latter don't have an air hole. Of course
when you get up there you can use larger containers....
This chart gave me a great guide for adapting other people's recipes to
volume.
What is great about glazes by volume is, that if you do not have a scale you
can borrow one for a day or so and then be scale free. (Good laugh here for
fruit growers!) You also are better equipped when you need to mix glazes at
a camp or school.
I measure out most of my glazes, slips that way. Quick, easy, peaceful.
And yes. Imperial measures work as well!
And, again, once more: this method is as dusty as any other. Wear your
mask, take off your work clothes as soon as you can after weighing out all
that powdered stuff, throw the clothes in the wash, shower and shampoo your
gorgissimo self.
Lili Krakowski
Be of good courage
Leigh Whitaker on tue 20 feb 07
In a message dated 2/20/2007 10:50:58 A.M. Eastern Standard Time,
mlkrakowski@CITLINK.NET writes:
1. You take an educated guess and start mixing let us say 1/4c Neph Sy,
1/4c clay, with 1/4 c flint.
You test. You look at the result. You gasp! You scream! You think! You
then mix same mixture but add let us say 1/4 c whiting at THIS end and 1/4
c. dolomite at THAT end and do blends. Or you add more clay at this end and
more silica at the other. This is fun if you have an idea what you are
doing.
2. The method I started with. I simply weighed out a simple recipe, put
each ingredient separately in a baggie, then measured the contents of each
baggie. This gave me a basis for mixtures as above.
3. This one took a while to do. I measured out each ingredient I had in
my glaze pantry. I measured each in 1T . 1/8c, 1/4c and up.
I weighed the result. I repeated each measurement twice: First time I used
my measuring cup as scoop, leveled off with a knife blade, as in cooking.
The second time I ladled the materials into the cup, again leveling off.
The result with some materials was identical, with others not.
I can see how this would work. You could either have a recipe based on
volumetric measurements, or you could "calibrate" your measuring cups to each
ingredient. Of course, this is going to depend on ingredients being homogenous
(will it work if you switch from milled rutile to granular? Or is rutile
from this company the same density as rutile from that one?). Or, like what
Wayne said, and like method #1, I guess, you could just not be too concerned
about the difference between volume and weight. With that method I do think I
would concerned about very heavy ingredients like iron oxide, etc... They are
really quite a bit heavier than say talc, aren't they? Of course if it's
working for you, that's great, you've obviously got it figured out. My concern
would be the OP taking a recipe that is formulated for weights and using
volumes, then not getting the results she wanted. She could then tinker with
it, but it would probably end up taking time and money to figure out
conversions that would work.
Here's something I was wondering about... In the lab, we often make
solutions from stocks. For example we will have stock solutions made up of
ingredients x, y and z. For simplicity say: 100 g/L x, 100 g/L y, and 100 g/L z.
Then if you wanted to make up a solution that had 1 g/L x, 2 g/L y, and 5 g/L
z, you just measure out the correct volume of each stock and dilute
accordingly. I can see something like this working for glaze recipes, but you would
have to be very very sure that your stock solution was mixed up well. Anyway,
in that case you'd only have to have access to a scale for one day, then
you'd have your stock solutions ready to go. Oh, I guess another disadvantage
would be your stocks would be heavy and take up a lot of room. Evaporation
could be a problem too. Okay, maybe not such a great idea!
Leigh
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Taylor Hendrix on tue 20 feb 07
Yes, Leigh. Lee Love does this very thing with his wet ladles (how do
you spell that word?). He knows the make up of his wet glaze material
(glazes) and dips accordingly. Great stuff.
Taylor, in Rockport TX
On 2/20/07, Leigh Whitaker wrote:
...> Here's something I was wondering about... In the lab, we often make
> solutions from stocks. For example we will have stock solutions made up of
> ingredients x, y and z. For simplicity say: 100 g/L x, 100 g/L y, and 100 g/L z.
> Then if you wanted to make up a solution that had 1 g/L x, 2 g/L y, and 5 g/L
> z, you just measure out the correct volume of each stock and dilute
> accordingly. I can see something like this working for glaze recipes, but you would
> have to be very very sure that your stock solution was mixed up well.
Ron Roy on thu 22 feb 07
Personally I think measuring by volume is a backward step. It may work for
some types of glazes but if you are interested in repeat performance from
your glazes - you are just introducing more variables.
If you must I would suggest a combination of volume and weight - volume for
the larger amounts and weight for the smaller amounts.
RR
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Bonnie Staffel on thu 22 feb 07
Hi Lili,
I attended a workshop by Brian Gartside who measures a lot of his glazes =
by
volume. This was just up my alley, making the mixture very like a cook. =
We
did a multitude of tests with varying degrees of success, but that was =
part
of the process. =20
If any of you ever have an opportunity to attend one of his workshops, =
it is
an eye opener as well as a lot of fun. He is an excellent presenter. I =
see
he is scheduling his 2007 workshop dates and you can access them by =
looking
up his website, I believe, which he keeps current. =20
Regards,
Bonnie Staffel
http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
DVD Throwing with Coils and Slabs
DVD Beginning Processes
Charter Member Potters Council
Lee Love on thu 22 feb 07
On 2/21/07, Taylor Hendrix wrote:
> Yes, Leigh. Lee Love does this very thing with his wet ladles (how do
> you spell that word?). He knows the make up of his wet glaze material
> (glazes) and dips accordingly. Great stuff.
Thanks Taylor,
My main glaze is measured by volume: wet ladle measure. It is:
3ladels wood ash
2 ladels ball clay
1 ladel Amakusa stone.
I work with washed ash and the clay and stone is slaked. The
top water, after the material settles out, is scooped/poured/ladeled
out. This method allows for consistant results and it is a method
used for over 800 years in China/Korea/Japan.
The key to any method is consistency. My teacher's glazing
is much more precise than what we are used to back home
. The other key is testing the glaze several times before you use it.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
Lili Krakowski on thu 22 feb 07
Apologies for being rather committed in this area, and belaboring the issue.
We all now know someone was a bit off track suggesting that a cup of one
ingredient would WEIGH the same as a cup of another.
And I repeat what I said in an earlier post. Ingredients may, often will,
WEIGH more if the measuring cup is used as a scoop (to get the material out
of its container) or if a spoon or similar is used to ladle the material
into the cup. I also said that a 1/2 c measuring cup may hold more or less
than two 1/4 c cups. These variations come, I think, from the way
materials pack down
Furthermore. If one is going to get serious about this it is a good idea to
spend a day with a scale and weigh out the contents of every size measuring
cup one has, for each ingredient, and to do it several times for scooped,
and, again several times, for poured. And work from the average.
That is how I arrived at my chart, as explained in the article in PMI.
I respectfully differ from Ron who considers measuring glazes out by volume
a backward step. It is neither forward NOR backward. It is a different
approach.
Look at it this way. Most recipes one finds--looking at Cooper here--call
for Neph.Sy, call for Feldspar, or Pot. Feldspar, or Soda Feldspar. They
call for kaolin and ball clay and dolomite and whiting. These general
"descriptions" are pretty loose.
(Reminding one of the joke about the mother in Little Italy who yelled:
"TONY! Lunch is ready!" out of the tenement window--and twenty little boys
showed up.) We all have exchanged stories about a feldspar that went off
the market and we never got that particular glaze again with the new spar.
We all have heard about a whiting that had a lot of magnesium in it, or why
one often buys calcium carbonate instead. Or about materials such as NephSy
that are mined in several parts of the world and are NOT identical. Not to
mention wood ash. EVERYTHING, just about, that we buy varies from batch to
batch. And, in my opinion, these variations have more effect than how we
measure out our ingredients.
And I will skip that the body underneath also changes and varies.....
OF COURSE there are glazes so neurotic they need to be pampered. They need
to be weighed and applied and fired with very special care. But for the
majority of glazes, once one is familiar with glaze, the measuring out
method works extremely well.
We all go to musea and are awed by the magnificence of old pots. I think we
should remember these are the result of craftsmanship and knowledge not of
scientific accuracy. The old potters took a fistful of this and a shovel
full of that, and that is how they arrived at their glazes. Yes. I am more
than a little uneasy about our rush to science....But that is for another
thread.
Lili Krakowski
Be of good courage
Tom Buck on thu 22 feb 07
Lili, others:
a basic problem with preparing glazes by volume is the
"fluffiness" of the raw materials, which leads to wide variations in the
actual molar make-up of the fired glaze. this especially happens with
certain raw materials (eg, gerstley borate) as you end one bag and start
a new one.
for sure, if you have a few workable recipes from materials on
hand one can fine-tune the volume approach, and have successful glazes
without a weigh scale accurate to 0.1 gram (or 1 g).
if you are committed to volume measurements, then you can reduce
the variations spread if you do this:
take a sizeable amount of each powder, and tamp it thoroughly, so
that your get a consistent "bulk density" (not a true density of the
mineral/chemical). if you do this with most of the powders, the volume
amount will be close to the same, cup or litre time after time. You could,
if you have a friendly potter handy with a scale close by, take a tamped
amount to her and have it weighed (try say three samples, and average it).
Then you will be more confident that your volume will actual match a
published recipe.
good pots Peace Tom B.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
brian on sun 25 feb 07
On 24/2/07 Alisa wrote ....
>Brian's cone 6 Base Glaze recipe is by volume and I have tested it with
>about 20 colorants, yepsie, in the archives!
Alisa, Steve, Bonnie
This discussion has wandered away from the topic of Behrens glazes
but i want to reply......as the subject of my basic glaze has
surfaced.
'Seems to me there are many variables in any glaze situation, not
the least the clay body a person uses. There are differences in
materials in another country, the thickness and method of application
and the firing atmosphere and cycle.........and more
The main thing is to get something that works for me, decorating is
my major interest and I have an easy. relaxed approach to designing
glaze surfaces without having to be concerned about precision and
accuracy........
I like to layer on top of high-iron mix with other coloured mixes of
the SAME glaze...with a few clear bisque areas to give brighter image
symbols
If anyone is interested
The glaze in question is here.....'will need translation (frit 4108
is 3134 I think)
http://www.gartside.info/briansbasicglaze.htm
and, much more important, how the glaze is used..... click on PRESENT WORK
http://gartsidesignz.com/onlinesales.html
Brian
--
Brian Gartside
main site http://www.gartside.info
sales/store http://gartsidesignz.com
Pukekohe, New Zealand
Ron Roy on sun 25 feb 07
Hi Lili,
I should explain my "backward step" comment.
It seems to me it is a good idea to apply as much science to our glazes as
is needed to fulfill out obligations to function.
I apply the same kind of thinking to clay as well - make it do what it is
supposed to do.
Just better for business - try not to disappoint your customers - the best
situation from both ends and people will use hand made pots more often and
we will all be happier.
What I don't understand is - what are the advantages of making glazes using
volume measuring? Why not use a more precise method if it is available -
and if you are calculating you have to weigh anyway.
The backward step I see as moving away from a more scientific method - and
I think we should be going in the other direction.
RR
>I respectfully differ from Ron who considers measuring glazes out by volume
>a backward step. It is neither forward NOR backward. It is a different
>approach.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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