Marjory R. Kline on mon 1 apr 96
Hi Mel,
Your posting perked me right up, since I've been working with Rhodes 21 and
adjusting it to get where I want to go. Thank to suggestions from other
clayarters, and especially Tom Buck, I have a lovely Rhodes glaze that shows
great promise. So, as Tom pointed out, Oxford spar (that's the original
Rhodes ingredient) has gone the way of the dinosaur. Your Rhodes 32 calls
for Oxford spar, china clay, dolomite, and whiting. If you need the
formula, I have the Rhodes book and will be glad to send it along. Rhodes
does not specify where the china clay, dolomite, and whiting come from. So
what to do? How does Ron Roy answer this? Curious to know.
Marjory
Ron Roy on tue 2 apr 96
Just to answer Marjory's question re china clay, dolomite and whiting. I
had asked Mel which materials he was using so I could calculate the glaze
and offer suggestions if there were indications of problems with durability
and fit.
The varations in feldspar - which is by far
the most important material in this case - must be taken into account.
There are many Kaolins -each having different analyses which will show up
to a small degree in the molecular formula. Dolomite is a variable material
depending where it is mined - the kind I use comes from N.E . USA. If I had
to use another kind I would ask my supplier, or better still - the mine to
provide an analysis. I have heard whiting is variable - Louis - care to
jump in here?
If your material analysis (which programs use to calculate molecular
formulas of melted glaze) are not at least close to reality you will get
misleading information. I spend considerable time keeping analysis up to
date to make sure I am not wasting my time with outdated and fictional
numbers.
More than you wanted to know - well, believe it or not I'm trying to be
brief and accurate. Actually I could go on about this for a long time but
will stop for now - stay tuned for further installments if necessary.
Bob Hanlin on sat 6 aug 05
I've had great surfaces with this glaze with 1% RIO & 1% Magnesium Dioxide. 32 1&1 I called it.
I've made the leap to cone 6 ox. I like it...but boy do I miss the C10 reduction glazes....but...now I sleep all night.
Bob in OKC
David Hendley on sun 7 aug 05
Rhodes 32 has to be one of the most tested glaze bases around.
In case you don't know about it, it is from the book "Clay and
Glazes for the Potter" by Daniel Rhodes. In the back of the
book he lists a few dozen glaze recipes, and this one is, of course,
number 32.
When I was at Big Creek Pottery in California in 1973, one of
my mates, Ed Hoe, did quite a few color tests with Rhodes 32.
The most interesting and surprising result came from adding
1% chrome oxide. This resulted in a pleasing brown glaze we
named "cafe au lait". Not a trace of green in it.
Of course what can make this even more interesting is overlapping
this glaze with another, and the green can magically appear.
Another interesting thing about Rhodes 32 is that 3 or 4 per cent
rutile can give you yellow-to-blue and everything in-between.
It is outstanding applied over a shiny black glaze.
I don't use Rhodes 32 too much because it can turn runny
and drip past your foot and onto the kiln shelf, and because,as a
quick analysis will show you, it is a silica-deficient glaze (typical
of most matt glazes) that will craze on most claybodies. The thing
about silica-deficient matts is that it is hard to detect the crazing
with the naked eye, but a 30X magnifier or india ink will quickly
reveal it. A few months of use on dinnerware will also show it.
David Hendley
I don't know nothin' but the blues, cobalt that is.
david@farmpots.com
http://www.farmpots.com
mel jacobson on sun 7 aug 05
i have always added a bit more silica.
and, i add rutile to my base to give it titanium.
it helps the fit, and the crazing.
david is totally correct with the glaze as it
is written in rhodes.
the glaze was developed by david shaner as a
glaze to cover high iron clay.
it works in that capacity.
it is not a `one glaze for everyone` sort of thing.
mel
from mel/minnetonka.mn.usa
website: http://www.pclink.com/melpots
http://home.comcast.net/~figglywig/clayart.htm
for gail's year book.
URL Krueger on sun 7 aug 05
Mel uses Rhodes 32.
But, Oops, Rhodes 32 is short of Silica.
No, Mel adds silica per David Shaner, he's OK.
New potter comes along and see that his hero, Mel, uses
Rhodes 32, so he will too. Finds Rhodes book, looks for
recepie 32 and makes up 20 gallons for his casseroles. A
bunch of casseroles hit the market with less than the best
of a glaze.
Is Mel's glaze still Rhodes 32 ?
In this case wouldn't it make sense to rename the glaze to
something else? Why not call it Shaner 32, or Mel's 32 ?
--
Earl K...
Bothell WA, USA
David Hendley on mon 8 aug 05
Earl is confused about all the variations of "Rhodes 32".
Here is your first mistake, Earl:
> New potter comes along and see that his hero, Mel, uses
> Rhodes 32, so he will too.
Of course, if you are just fooling around, go ahead and find
glazes that sound good, mix them up, and use them. The right
thing to do, of course, if you are serious about having good
glazes, is to learn glaze calculation and limit formulas, and
always [Always] run any glaze recipe through the program
before you decide to use it. With experience, you will know
just by looking at the numbers if it will craze on your
claybody, before your kiln is even turned on.
Your second mistake is:
> Finds Rhodes book, looks for
> recepie 32 and makes up 20 gallons for his casseroles.
Twenty gallons?! Of a glaze you have never used before? For
me, 1000 grams (less than half a gallon) is a good test-batch
size. For anyone smaller than a factory with 10 employees, 20
gallons of glaze for a first test is way, way too big a batch.
With my claybody, I think it is impossible to add enough silica to
"Rhodes 32" to stop it from crazing, without substantially changing
the character of the glaze. I have yet to find a true magnesia matt
glaze that does not, on close examination, exhibit crazing.
I still use Rhodes 32 because I like the look of it, but I know
what I will be getting.
David Hendley
I don't know nothin' but the blues, cobalt that is.
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
> Mel uses Rhodes 32.
> But, Oops, Rhodes 32 is short of Silica.
> No, Mel adds silica per David Shaner, he's OK.
>
> New potter comes along and see that his hero, Mel, uses
> Rhodes 32, so he will too. Finds Rhodes book, looks for
> recepie 32 and makes up 20 gallons for his casseroles. A
> bunch of casseroles hit the market with less than the best
> of a glaze.
>
> Is Mel's glaze still Rhodes 32 ?
> In this case wouldn't it make sense to rename the glaze to
> something else? Why not call it Shaner 32, or Mel's 32 ?
Ron Roy on wed 10 aug 05
I find myself in agreement with both Earl and David - what they are saying
is worth paying attention to.
I do think that Mel should say he uses a variation of Rhodes 32 - not bad
to simply say Mels Variation of Rhodes 32 - and give the recipe or at least
how it has been adjusted.
I also think David means a clay matte - I have never seen one that does
not craze but have not tried to make one with spodumene yet. A magnesia
Matte is a different ball game - in which you can have enough silica and
alumina. In fact - because magnesium has such a low expansion - care must
be taken to make sure the expansion is not too low.
>Earl is confused about all the variations of "Rhodes 32".
>Here is your first mistake, Earl:
>
>> New potter comes along and see that his hero, Mel, uses
>> Rhodes 32, so he will too.
>
>Of course, if you are just fooling around, go ahead and find
>glazes that sound good, mix them up, and use them. The right
>thing to do, of course, if you are serious about having good
>glazes, is to learn glaze calculation and limit formulas, and
>always [Always] run any glaze recipe through the program
>before you decide to use it. With experience, you will know
>just by looking at the numbers if it will craze on your
>claybody, before your kiln is even turned on.
>
>Your second mistake is:
>
>> Finds Rhodes book, looks for
>> recepie 32 and makes up 20 gallons for his casseroles.
>
>Twenty gallons?! Of a glaze you have never used before? For
>me, 1000 grams (less than half a gallon) is a good test-batch
>size. For anyone smaller than a factory with 10 employees, 20
>gallons of glaze for a first test is way, way too big a batch.
>
>With my claybody, I think it is impossible to add enough silica to
>"Rhodes 32" to stop it from crazing, without substantially changing
>the character of the glaze. I have yet to find a true magnesia matt
>glaze that does not, on close examination, exhibit crazing.
>I still use Rhodes 32 because I like the look of it, but I know
>what I will be getting.
>
>David Hendley
>I don't know nothin' but the blues, cobalt that is.
>david@farmpots.com
>http://www.farmpots.com
>
>
>
>----- Original Message -----
>> Mel uses Rhodes 32.
>> But, Oops, Rhodes 32 is short of Silica.
>> No, Mel adds silica per David Shaner, he's OK.
>>
>> New potter comes along and see that his hero, Mel, uses
>> Rhodes 32, so he will too. Finds Rhodes book, looks for
>> recepie 32 and makes up 20 gallons for his casseroles. A
>> bunch of casseroles hit the market with less than the best
>> of a glaze.
>>
>> Is Mel's glaze still Rhodes 32 ?
>> In this case wouldn't it make sense to rename the glaze to
>> something else? Why not call it Shaner 32, or Mel's 32 ?
>
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Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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