Ivor and Olive Lewis on mon 12 jun 06
Dear Friends
My reading this week revealed information about the discharge of =
volatile compounds when clays or glazes are being fired. In particular a =
compound F2O was mentioned. This is supposed to evolve when Calcium =
Fluoride (CaF2) is heated. It can also be represented OF2. So it known =
as either Fluorine Monoxide or Oxygen Difluoride.
I have little information relating to this gas other than that it is =
highly reactive and also very poisonous. (Greenwood and Earnshaw).
The reaction given in my source says Calcium Fluoride is oxidised. The =
equation given was :
CaF2 + O2 =3DCaO + F2O
Since we have Calcium Fluoride on our list of ceramic raw materials and =
Fluorine is an element in other minerals given as glaze ingredients =
perhaps Clayart members might like to consult their own library =
resources and pass on anything useful.
Best regards.
Ivor Lewis.
Redhill,
South Australia.
William & Susan Schran User on mon 12 jun 06
On 6/11/06 9:58 PM, "Ivor and Olive Lewis" wrote:
> Since we have Calcium Fluoride on our list of ceramic raw materials and
> Fluorine is an element in other minerals given as glaze ingredients perhaps
> Clayart members might like to consult their own library resources and pass on
> anything useful.
Ivor,
Some interesting sites:
http://www.atsdr.cdc.gov/toxprofiles/phs11.html - how flourides are in our
environment
http://www.p2pays.org/ref/23/22780.pdf - reducing calcium flouride in the
whiteware sector
http://www.zju.edu.cn/jzus/2001/0103/010310.htm - flourine emmission from
clay materials
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
Richard White on mon 12 jun 06
Ivor, my knowledge of chemistry is nothing compared to yours. I have heard,
though, that one of the obvious signs of a potter with an unvented electric
kiln is windows in the kiln room that you cannot see out. The fluorine
gases produced each firing etch the glass on the inside (and everything
else in the room too, but the glass is more obvious). So that would be
consistent with your reading.
dw
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