Fredrick Paget on wed 28 nov 07
I wonder about that water softener salt. Could it be potassium
chloride? They were selling that at Home Depot in Santa Rosa for
water softener use a few years ago.
You can test it by the flame color if you hold a little in a blue
flame. Sodium will give a yellow orange flame color and potassium is
I have always wondered what potassium chloride would in a salt
firing. Maybe you found out why it is not used.
Sodium and potassium are in the same periodic table group and have
somewhat similar chemistries.
>.............. this last kiln load, every thing turned out grey. Very
>little color. Salt coverage was good, reduction was like normal. we used
>water softner salt because we were out of rock salt. any suggestions as to
>what happened and how to change it. James O. Kenney
Twin Dragon Studio
Mill Valley, CA, USA
James O. Kenney on wed 28 nov 07
I am a student at Msu in the ceramic department. I have fired the salt
kiln several times with different results. I have been using a white
stoneware body glazed with different colored glazes. The kiln before this
last one the clay body turned a dark rich brown and there was color in the
glazed areas. this last kiln load, every thing turned out grey. Very
little color. Salt coverage was good, reduction was like normal. we used
water softner salt because we were out of rock salt. any suggestions as to
what happened and how to change it. James O. Kenney
vpitelka on thu 29 nov 07
I think I missed the original post on this subject, but we used water
softener salt one time, and got pretty poor results. Now we only use pure
rock salt, which we get in 50-lb bags from our local farmer's co-op.
Appalachian Center for Craft
Tennessee Tech University
Ivor and Olive Lewis on fri 30 nov 07
Dear Fred Paget,
You ask <<...I have always wondered what potassium chloride would in a =
firing. Maybe you found out why it is not used....>>
You can buy Potassium chloride, its about $5.00 for 100 gm in the =
supermarket as a salt substitute. I used to get softener salt (NaCl) for =
$5.00 for a 50 lb bag. NaCl wins on price.
If you get into the literature you will find out that during WW1 there =
was a shortage of potassium for the manufacture of explosives. So they =
proposed to recover Potassium from slag created during the production of =
pig iron by using Potash felspar as a supplementary flux and adding =
common salt to the charge. They proposed to recover Potassium Chloride.
If you had a clay that was fluxed with K Felspar it would not make a =
But it might if you had a high Iron glaze.=20
The following Chemistry is possible. It explains the dense brown smoke =
that was discharged from Pipe Work Kilns that were fired on Tyneside =
though they were salted with NaCl
3KCl + Fe'' =3D FeCl3 + 3K'
4K' + O2 =3D 2K2O
K2O+4SiO2 =3D K4Si4O10 MP 770 deg C
2FeCl3 + 3H2O =3D Fe2O3 +6HCl
Interesting to speculate.
In the Flame test Sodium yellow tends to mask the delicate violet. To =
see that you have to filter with cobalt glass.