[Clayart] Iron

ronroy at ca.inter.net ronroy at ca.inter.net
Tue Jul 18 20:53:03 EDT 2017


Hi Antoinette,

You can find the article I wrote on my web site.

www.ronroy.net

Custer is uneven so always better to test before using a new bag.

I can reformulate glazes that have the old custer subbing in the new.  
The old Custer changed at least 15 years ago - they did not and do not  
put any dates on the bags so the only way to know what you had or have  
is to have an analysis done. If you bought your Custer in the last 15  
years you probably have the new - which is short of potassium any  
about 3%.

RR

Quoting Porcelain byAntoinette <porcelainbyantoinette at gmail.com>:

> Thanks Paul will google and see if I can find the articles. I know  
> Custer is purer than it used to be. Antoinette.
>
> Sent from my iPhone
>
>> On Jul 18, 2017, at 10:28 AM, Paul Gerhold <gerholdclay at gmail.com> wrote:
>>
>> There are several good articles online as to how Custer has changed  
>> particularly one by Ron Roy. And G200 which is a Custer equivalent  
>> has also changed.
>>
>> On top of that you might check to see if the mesh of the Silica you  
>> are using is different. Can make a significant difference in some  
>> glazes.
>>
>> Also  bone  ash is quite hygroscopic and will gain moisture over  
>> time reducing the actual percentage in the glaze. My suggestion  
>> would be to add more bone ash in increments to see if it fixes the  
>> glaze
>>
>> Paul.
>>
>>
>>
>> Paul
>>
>> Sent from my iPad
>>
>>> On Jul 18, 2017, at 10:32 AM, Antoinette Badenhorst  
>>> <porcelainbyantoinette at gmail.com> wrote:
>>>
>>> Thank you to those of you that took the time to answer. I do not have a
>>> conclusion of why this turned out brown yet. Will use new iron and test.
>>>
>>> One of you mentioned the bone ash - artificial versus real, which raised
>>> the question with me if the bone ash may "expire", since I used the real
>>> thing.
>>>
>>> As I mentioned before: I used the exact same materials that I used on
>>> porcelain before. All these (except the silica and maybe the custer) came
>>> from batches that I had in my studio for the best part of 15-18 years. (yes
>>> I have some valuable materials.....)
>>>
>>> The recipe is no secret, it is similar to many others available online, but
>>> the reason I want to do it again is because over time some of the plates
>>> that I glazed with it wore off, which told me that there is maybe not
>>> enough silica in this recipe. So I want to alter it some, but first need to
>>> make sure I have the color right.
>>>
>>> * Ralph’s Terracotta.*
>>>
>>>
>>>
>>> Custer F.                           41
>>>
>>> Talc                                     9
>>>
>>> Bone ash                          13
>>>
>>> Lith Carb.                            2
>>>
>>> Kentucky Ball clay            13
>>>
>>> Silica                                 13
>>>
>>>
>>>
>>> Add:
>>>
>>>
>>>
>>> Iron ox                                 9
>>>
>>>
>>> Anyone else have some input? I will appreciate that.
>>>
>>>> On Sat, Jul 15, 2017 at 6:06 AM, Paul Gerhold  
>>>> <gerholdclay at gmail.com> wrote:
>>>>
>>>> Antoinette,
>>>> Iron oxide does not change under any conditions that your supply would
>>>> experience. I have been using the same supply of RIO for thirty plus years
>>>> and no changes have occurred.  Probably a problem with some other  
>>>> chemical.
>>>>
>>>> Paul
>>>>
>>>> Sent from my iPad
>>>>
>>>>>> On Jul 13, 2017, at 8:20 PM, Porcelain byAntoinette <
>>>>> porcelainbyantoinette at gmail.com> wrote:
>>>>>
>>>>> Hi guys. I have mixed up a iron red glaze that I did not mix for a
>>>> while. I used ingredients that is 10 years old and older end the  
>>>> end result
>>>> was a flat brown instead of the reach read brown that it was before.
>>>>> I repeated the recipe, thinking I made a mistake, ending up with the
>>>> same results.
>>>>> Then I thought maybe I used the wrong recipe and compared it with
>>>> similar recipes getting to the conclusion that I did not make a mistake.
>>>>> So someone said the problem is the iron that changed over time. This was
>>>> the first time I heard that in all the 36+ years I am in clay. Is  
>>>> that true
>>>> and if so, can I fix it? I assume that if that is true, it has to do with
>>>> the oxidation process.
>>>>> Antoinette Badenhorst.
>>>>>
>>>>> Sent from my iPhone
>>>
>>>
>>>
>>> --
>>>
>>> Antoinette Badenhorst
>>>
>>>
>>> PorcelainByAntoinette <http://www.porcelainbyantoinette.com/>
>>>
>>> TeachinArt.com
>>>
>>>
>>> [image: banana envelope web]
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>



Ron Roy
ronroy at ca.inter.net
Web page ronroy.net




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