SUBSCRIBE Clayart Anonymous on fri 12 nov 10
There are two standardized forms for glaze recipes right? In the percenta=
=3D
ge
form all material percentages add to 100% including colorants. You use th=
=3D
ese
percentages to figure the amount of each material to add.=3D20
In the second base glaze recipe form, the base glaze has percentages that=
=3D
add to 100%. But, there is an addition of colorants that will contain one=
=3D
or
more ingredients to add to the 100% base glaze. When you add all of the
ingredients together you get 105, 109, or 100.5% depending on what you ad=
=3D
d
to the base. Clayheads start with a clear base glaze then put different
colorants in to create other results.=3D20
My questions:
1. Are there two standardized forms for glaze recipes?
2. Can you convert between the two?
3. Either form works fine when mixing larger batches you just have to do =
=3D
the
correct math for the base glaze method.=3D20
4. The clay gods did not come down off of the primary clay mountain to
render one or the other method as THE standard from?
Thanks,
Standardless Clayhead
Richard White on fri 12 nov 10
There is no standard, there is no clay god, only the kiln gods, and you'=
=3D
d
better not mess with them. The two most common methods are those you
describe. A third method in fairly common use is "get a recipe from anoth=
=3D
er
potter and however much of whatever he/she put in, you put in." It may to=
=3D
tal
743, or it may total 4,743, or maybe even 3,095, including the oxide/stai=
=3D
n
colorants and bentonite. IMO, the most useful (and for thus for me, corre=
=3D
ct)
method is the one in which the base glaze materials only add to 100. The
colorants or other additives are in addition to the base, so the grand to=
=3D
tal
may be more. Further, any color variations may have a different grand tot=
=3D
al
because of the different amounts of the alternative colorants, but the ba=
=3D
se
recipe is unchanged.=3D20
The reason I like this method is so that I can directly compare the
composition of two recipes to determine their similarities or differences=
=3D
both at the material level and at the molecular level. While a unity
calculation can be made from any recipe total, the colorants and additive=
=3D
s
do not affect the unity calculation and generally don't have much effect =
=3D
on
the performance of the base glaze, so balance the base glaze total to 100=
=3D
and put the additions below that. This methodology also allows me to judg=
=3D
e
what are the actual percentages of the colorant oxides in relation to the=
=3D
base so that I can tell when they are leaning toward the unsafe levels.=3D2=
0=3D
For example, 5% copper may be leaning toward a bit too much to stay in a
marginally stable glaze, but maybe ok in a really solid stable glaze reci=
=3D
pe.
If, however, you gave me a very similar recipe but calculated to grand to=
=3D
tal
out at 100, including 15% zircopax, 2% bentonite, and 1% cobalt (plus the=
=3D
5%
copper), the actual percentage of copper compared to the base (which is n=
=3D
ow
only 77% of the gross recipe) will be well over 6%, which likely makes th=
=3D
at
an unsafe glaze.=3D20
My opinions, YMMV
dw
William & Susan Schran User on fri 12 nov 10
On 11/12/10 11:31 AM, "SUBSCRIBE Clayart Anonymous" >
wrote:
> 1. Are there two standardized forms for glaze recipes?
Most folks use, as do glaze calculation programs, the guideline of the base
,materials adding up to 100%, then colorants are a percentage of this
(colorants are usually not part of the base recipe).
> 2. Can you convert between the two?
You can use any system that makes sense to you. I have seen recipes where
colorants or opacifiers are part of the base.
> 3. Either form works fine when mixing larger batches you just have to do =
the
> correct math for the base glaze method.
Yes, doing the correct math so that all materials stay in the same
proportion/percentage.
> 4. The clay gods did not come down off of the primary clay mountain to
> render one or the other method as THE standard from?
The clay gods care only about the firings, they care nothing about the
glazes.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Snail Scott on fri 12 nov 10
On Nov 12, 2010, at 10:31 AM, SUBSCRIBE Clayart Anonymous wrote:
> 1. Are there two standardized forms for glaze recipes?
The 'base recipe =3D 100%, plus colorants' version is the
most prevalent in my experience, but not all glazes can
be broken down so distinctly. Many popular glazes have
nominal 'colorants' which are also integral parts of the
melt chemistry, and can't be simply listed separately
without implying that they are to some extent optional,
which they are not. So, though the 'base plus colorant'
version is very handy for glazes whose colorants can
be tinkered with pretty freely, and is a useful tool for
comparing chemistry independent of color, the 'full
recipe' version is also necessary. Neither is better in
any fundamental way; each has its appropriate uses.
>
> 2. Can you convert between the two?
No problem. Just take the 'base plus colorants' as a
simple list of quantities, add them all together, then
normalize to 100% to show each ingredient as a
percentage of the new total. To convert a full recipe
to 'base plus colorants', add up all the non-colorants
and normalize that to 100%, then use the same
conversion on all the colorants.
>
> 3. Either form works fine when mixing larger batches you just have
> to do the
> correct math for the base glaze method.
I wouldn't bother. For a typical five-gallon bucket, the
volume of colorant in most recipes is so small as to
have no real effect on the fullness of the bucket. The
density of other large-percentage ingredients - say,
gerstley borate versus frit - is a bigger factor. I just
figure 10,000 grams per bucket, or 8,000 if there's a
lot of clay or GB, or 12,000 if there's a lot of frit, for
instance. No math at all.
>
> 4. The clay gods did not come down off of the primary clay mountain to
> render one or the other method as THE standard from?
I suspect the clay gods prefer volumetric measurements,
the third option we haven't even discussed yet. It seems
more likely for nontechnological practices, as most divine
lifestyles of myth and fable seem to be. Not: 32.4% of this,
21.7% of that, but rather, three scoops of this, two of that...
-Snail
ivor and olive lewis on sun 14 nov 10
"There are two standardized forms for glaze recipes right?"
Wrong ! !
Standardize in this context means being accountable to a practice
which has universal acceptance. So we have standards for mass of materials,
eg Kilograms, Time, we all agree about the Second, Distance, nothing wrong
with the metre
It seems better to say that there are two acceptable ways of representing a
glaze batch recipe and that a worker should use the one they think
appropriate to their own workshop practice and stick with it.
In the examples given, it's a question of Accounting .... where to draw the
Bottom
Line. My own preference is to Draw the Line below the glaze batch
ingredients then put compounds augmenting colour, opacity, surface texture
etc. below the line.Why ??? The Math is easier.
Regards,
Ivor Lewis,
REDHILL,
South Australia
Eric Hansen on mon 15 nov 10
It all goes back to certain glazes such as "Reeves Base" which is a
kind of clear glaze to which different colorants can be added. One
glaze with many colors. I have seen artists do this, one piece with a
base glaze done in several different colors. So in that context it
makes sense for the base glaze to equal 100 and the colorant oxides to
be ADDED to the 100, making a number which is more than 100, which of
course if you divide by 100 will get you to the other way of
expressing the same glaze. Its all those tricky numbers, huh? Some
very "important" potters will sometimes take and ingredient out,
leaving less than 100, or add an ingredient, giving more than 100,
then sweep the dirt under the carpet by listing the ingredients as,
for example: "14.875 % whiting" etc. when in fact they themselves
NEVER measure it that way. Lots of smoke and mirrors and secret voodoo
- h -
On Fri, Nov 12, 2010 at 11:31 AM, SUBSCRIBE Clayart Anonymous
wrote:
> There are two standardized forms for glaze recipes right? In the percenta=
ge
> form all material percentages add to 100% including colorants. You use th=
ese
> percentages to figure the amount of each material to add.
> In the second base glaze recipe form, the base glaze has percentages that
> add to 100%. But, there is an addition of colorants that will contain one=
or
> more ingredients to add to the 100% base glaze. When you add all of the
> ingredients together you get 105, 109, or 100.5% depending on what you ad=
d
> to the base. Clayheads start with a clear base glaze then put different
> colorants in to create other results.
>
> My questions:
> 1. Are there two standardized forms for glaze recipes?
> 2. Can you convert between the two?
> 3. Either form works fine when mixing larger batches you just have to do =
the
> correct math for the base glaze method.
> 4. The clay gods did not come down off of the primary clay mountain to
> render one or the other method as THE standard from?
>
> Thanks,
> Standardless Clayhead
>
--
Eric Alan Hansen
Stonehouse Studio Pottery
Alexandria, Virginia
americanpotter.blogspot.com
thesuddenschool.blogspot.com
hansencookbook.blogspot.com
"Simplify, simplify, simplify" - Thoreau
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