Susan Ford on thu 17 feb 00
If I wanted to add, say 5% Wollastonite to a glaze
formula, how would I go about re-adjusting the
formula to add to 100%? My gut reaction is to
simply divide the new total into the individual
percentages to get the new percentages.
What I am trying to do is slightly reduce the
extreame shiny-ness of a glaze. It is a beautiful
transparent green, fits well, but almost looks like
Duncan clear, it's so extreamly shiny.
The recipe I'm using is:
Deep Green, cone 4-6 Ox.
whiting 23.6
custer feld. 45.5
ball clay 21.8
flint 9.1
____
100%
Add:
zinc ox. 9.10%
cobalt carb. .25%
copper carb. 3%
This glaze fits my ware nicely, and pools beautifuly
in texture, plus is a deep olive green on stoneware
and a slightly bluish green on porcelain. I just want
to reduce the shinyness of it a bit.
I am going to test the base glaze without the
colorants in order to see if it would make a good
clear glaze and add other colorants to it, because I
like pooling glazes.
Susan
---
Susan K. Ford
Norman, Oklahoma
http://www.clueless.norman.ok.us/sf/rerhome.htm
"When the chips are down, the buffalo is empty."
Jim Cullen on fri 18 feb 00
Good questions. This e-mail is not an answer to any of them. But:
We've all been there and CLAYART is the place to be.
My suggestion, buy a software program. I use and use and use... INSIGHT 5.
It's greast and allows you to see the changes you're talking about. Of course
it takes some getting used to, to figure out what the program is telling you,
but it is manageable for the chemist and the non-chemist. If you're really
interested in mixing glazes I highly recommend the GLAZE TECHNOLOGY course
taught by RON ROY at Canadore College, North Bay, Ontario, Canada. It's great
and Ron is a terrific instructor and shares his knowledge with any and all
who are interested.
There are other programs out there that provide similar information, but each
program is different and none of them do everything. I have several
HYPERGLAZE, GlazeChem demo, and MATRIX demo. I'm most familar with INSIGHT.
Keep those questions coming. We have some of the best people on CLAYART and
they will collectively give you more information than you ever expected was
available or necessary.
We are all learning together and your questions sometimes slap us up side the
head and remind us where we came from.
HAPPY GLAZING and KEEP CENTERED
Cullen
Naperville, Illinois
Paul Lewing on fri 18 feb 00
Susan Ford wrote:
>
> ----------------------------Original message----------------------------
> If I wanted to add, say 5% Wollastonite to a glaze
> formula, how would I go about re-adjusting the
> formula to add to 100%? My gut reaction is to
> simply divide the new total into the individual
> percentages to get the new percentages.
>
> What I am trying to do is slightly reduce the
> extreame shiny-ness of a glaze. It is a beautiful
> transparent green, fits well, but almost looks like
> Duncan clear, it's so extreamly shiny.
Susan, I don't have time tonight to run your recipe through a glaze calc
program, but in general, I'd say you should add some more clay to this
to take down the shine. I think wollastonite would just make it
glossier.
But I did want to address your comment about this not then adding up to
100 after you had made your additions. Your gut reaction is correct.
To make the new recipe add up to 100, you divide the old number for each
material by the new total. In your example of adding 5 wollastonite,
you would then divide the 23.6 feldspar by 105, and so on.
However, especially for the purposes of testing, there's no reason it
has to add up to 100. In fact, most of us would say it already doesn't
add up to 100, since most people would include the 9.1 zinc oxide in a
100-gram recipe as well. I'd consider what you have here a 109.1 g
batch, with the colorants added to that.
I get this question in workshops a lot about "what do I take out to make
it add up to 100 if I add that?" And also the question about "is this
grams or percentages?" Well, if it adds up to 100, then those numbers
are both grams (or any other weight measurement, for that matter) and
percentages. If it adds up to some number other than 100, the numbers
are still that weight measurement, but they're no longer percentages.
If you do that division thing we just talked about, what you're really
doing is converting it from weight measurements to parts of 100 of those
weight measurements. I'll never forget a few years ago when my mother
had one of those "AHA!" moments when I explained to her that the word
percent was Latin for "parts (per) of one hundred (cent)".
So when you add something, you don't then have to subtract an equal
amount of some other material to make it add up to 100. If you like,
you can think of it as subtracting a bit of everything, in the
proportions that they were each present in the original.
Anyway, it's only a convention that the materials in a base, or
uncolored, glaze recipe should add up to 100, and the colorants should
be listed as additions. It's done this way only because it makes it
easier to compare recipes. Imagine if all colored glaze recipes were
adjusted to add up to 100. You wouldn't necessarily recognise that a
glaze that had 1% colorant was the same recipe as if you added 5% more
colorant, because then all the numbers would be different. Does that
make sense? I hope it helps.
Paul Lewing, Seattle
Ron Roy on sat 19 feb 00
Thanks Jim, I feel warm all over - RR
>----------------------------Original message----------------------------
>Good questions. This e-mail is not an answer to any of them. But:
>
>We've all been there and CLAYART is the place to be.
>
>My suggestion, buy a software program. I use and use and use... INSIGHT 5.
>It's greast and allows you to see the changes you're talking about. Of course
>it takes some getting used to, to figure out what the program is telling you,
>but it is manageable for the chemist and the non-chemist. If you're really
>interested in mixing glazes I highly recommend the GLAZE TECHNOLOGY course
>taught by RON ROY at Canadore College, North Bay, Ontario, Canada. It's great
>and Ron is a terrific instructor and shares his knowledge with any and all
>who are interested.
>
>There are other programs out there that provide similar information, but each
>program is different and none of them do everything. I have several
>HYPERGLAZE, GlazeChem demo, and MATRIX demo. I'm most familar with INSIGHT.
>
>Keep those questions coming. We have some of the best people on CLAYART and
>they will collectively give you more information than you ever expected was
>available or necessary.
>
>We are all learning together and your questions sometimes slap us up side the
>head and remind us where we came from.
>
>HAPPY GLAZING and KEEP CENTERED
>Cullen
>Naperville, Illinois
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Ron Roy on sat 19 feb 00
Hi Susan,
The zinc should be included in the main body of the recipe so if you are
stating this recipe in the coventional way it should read -
Custer - 37.25
Whiting - 19.25
Zinc ox - 7.50
Ball - 18.0
Silica - 18.0
Total - 100
This would mean your colour oxides would need to be adjusted down a bit -
the copper carb from 3 down to 2.5 approx. I have rounded off the numbers
but it will look like exactly the same glaze.
To take some of the shine off simply do 4 recipes lowering the zinc by one
% each time - when you have lost enough shine recalculate to 100 as others
have suggested - divide total into each material number and multiply by
100.
A = 75
B = 50
C = 25
150 total
I multipy by 100 first to cut out a step so finding the % for A is:
7500/(divided by) the total 150 = 50
B = 5000/150 = 33.33
C = 2500/150 = 16.66
Total = 99.99
By the way the expansion rate of zinc is higher than the glaze so there is
little danger of the new version crazing.
Any questions?
>----------------------------Original message----------------------------
>If I wanted to add, say 5% Wollastonite to a glaze
>formula, how would I go about re-adjusting the
>formula to add to 100%? My gut reaction is to
>simply divide the new total into the individual
>percentages to get the new percentages.
>
>What I am trying to do is slightly reduce the
>extreame shiny-ness of a glaze. It is a beautiful
>transparent green, fits well, but almost looks like
>Duncan clear, it's so extreamly shiny.
>
>The recipe I'm using is:
>
>Deep Green, cone 4-6 Ox.
>
>whiting 23.6
>custer feld. 45.5
>ball clay 21.8
>flint 9.1
> ____
> 100%
>Add:
>zinc ox. 9.10%
>cobalt carb. .25%
>copper carb. 3%
>
>This glaze fits my ware nicely, and pools beautifuly
>in texture, plus is a deep olive green on stoneware
>and a slightly bluish green on porcelain. I just want
>to reduce the shinyness of it a bit.
>
>I am going to test the base glaze without the
>colorants in order to see if it would make a good
>clear glaze and add other colorants to it, because I
>like pooling glazes.
>
>Susan
>---
>Susan K. Ford
>Norman, Oklahoma
>http://www.clueless.norman.ok.us/sf/rerhome.htm
>
>"When the chips are down, the buffalo is empty."
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
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