louroess2210 on sun 25 mar 07
On Mar 25, 2007, at 12:11 PM, Ron Roy wrote:
> The ideal solution to flocculating clay - and/or counteracting
> deflocculation is Epsom salts in my opinion. It works and keeps on
> working.
> It works right away and does not interfere with subsequent beneficial
> aging.
>
> RR
Ron, if smell is an indicator, wouldn't paper clay be considered very
"ripe"? Maybe just a little in clay would make it better but not
interfere with its throwing properties. Jist wondering.
Regards, Lou
Ron Roy on mon 26 mar 07
Hi Lou,
I have never used paper clay but - I do think the paper rotting does happen
- and fast. Most clay makers use a fungicide to slow it down.
I think adding stuff to clay makes for some very bad smelling clay so I
don't recommend it.
The Epsom salts do the trick.
Not all clay needs it by the way - porcelains need it because of the high
amounts of spar or neph sy that tend to deflocc over time.
What we are really talking about when we (potters) say plasticity is very
often the ability of the clay to hold together well - it wants to stretch
rather than break. Thats why it's better to thrown with - you can work
faster with well aged clay - better than with fresh.
Besides the coil around your finger - if you roll a coil and pull it apart
- clay that has good plasticity will get thinner before it parts - short
clay just breaks without getting thinner.
Hard to explain all that - a simple demo would be worth a thousand words.
RR
>> The ideal solution to flocculating clay - and/or counteracting
>> deflocculation is Epsom salts in my opinion. It works and keeps on
>> working.
>> It works right away and does not interfere with subsequent beneficial
>> aging.
>>
>> RR
>
>Ron, if smell is an indicator, wouldn't paper clay be considered very
>"ripe"? Maybe just a little in clay would make it better but not
>interfere with its throwing properties. Jist wondering.
>Regards, Lou
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ivor and Olive Lewis on tue 27 mar 07
Dear Dave,
You asked.
>> As I'm sure you are aware plasticity of clay bodies
>> is influenced to some extent by at least these 5
>> factors and there must be others besides these:
>> 1. particle packing
>> 2. moisture content
>> 3. adsorbed organics
>> 4. pH
>> 5. ionic concentration and strength
I think particle shape has to fit into your list somewhere. So must the =
proportional quantities of the ingredients, as mass and as volume. Bulk =
Density of ingredients may also play a part. I have reservations about =
'"Organics".
I cannot believe that once mined, clay or minerals become contaminated =
but adding CMC, vinegar, urine would to a limited degree increase the =
concentration of "Organic".
But who would know what the bacterial volume would be or if Anthrax and =
Tetanus bacilli were represented in the microbial population of subsoil =
clay. Soil Scientists must have records of population studies
At the end of the day residues of soil microbial activity are Water, =
Carbon dioxide and colloidal Humic acid.
As far as I know, no one took up my challenge to analyse the exhaust =
from a "de-airing" Pugmill so we know nothing about the quantity of CO2 =
in any sample of clay. Its presence in solution would ensure an acid =
environment and assist retention of a flocculated structure. If water =
from organic putrefaction and decomposition does not evaporate then it =
will assist in making our clay softer. As a Colloid, Humic acid might =
help with water retention and add to the slippery feel of things.
Reading the "Whiteware Papers" might enhance our knowledge.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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