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low-fire salt fuming - is it safe?

updated sun 21 jun 98

 

Pottery Guide Online on thu 18 jun 98

Recently, I had a positive experience with a low fire salt fuming firing.
My instructor invited me to join him in a process that he only does once or
twice a year at our public studio. I'm writing on his behalf.

Another instructor in our lab is questioning the safety of the firing we
did. They say it is unsafe and that we have permanently damaged the kiln
and we should dismantle the kiln used forever. Assuming that the salt
fuming is safe, this would be a shame as the results we achieved were truly
inspiring.

Please comment on the potential health hazards or let me know if what we
did is safe.

We loaded a saggar with our pots, organic materials, and salt. We put the
salt on the bottom of the saggar and we built trays within the saggar for
additional salt. We fired the propane fueled kiln to approx. cone 08 for
less than 5 hours. During the five hours the smoke does get heavy for a
while, but I thought that the harmful fumes burned off before they left the
kiln.

Help, we don't want to endanger anyone's health.

Thanks in advance,
Jules in Colorado where it's snowing in the high country in mid-June!

Stephen Mills on fri 19 jun 98

During an experimental firing weekend for our Pottery group the year
before last. A mixed sagger firing to approximately that cone took place
in our host's main gas kiln. It included a sagger as you describe and
was very successful.
The Kiln has now returned to normal production without ill effect to the
kiln or subsequent production.

Steve
Bath
UK


In message , Pottery Guide Online writes
>----------------------------Original message----------------------------
>Recently, I had a positive experience with a low fire salt fuming firing.
>My instructor invited me to join him in a process that he only does once or
>twice a year at our public studio. I'm writing on his behalf.
>
>Another instructor in our lab is questioning the safety of the firing we
>did. They say it is unsafe and that we have permanently damaged the kiln
>and we should dismantle the kiln used forever. Assuming that the salt
>fuming is safe, this would be a shame as the results we achieved were truly
>inspiring.
>
>Please comment on the potential health hazards or let me know if what we
>did is safe.
>
>We loaded a saggar with our pots, organic materials, and salt. We put the
>salt on the bottom of the saggar and we built trays within the saggar for
>additional salt. We fired the propane fueled kiln to approx. cone 08 for
>less than 5 hours. During the five hours the smoke does get heavy for a
>while, but I thought that the harmful fumes burned off before they left the
>kiln.
>
>Help, we don't want to endanger anyone's health.
>
>Thanks in advance,
>Jules in Colorado where it's snowing in the high country in mid-June!
>

--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk

Pottery Guide Online on fri 19 jun 98

Recently, I had a positive experience with a low fire salt fuming firing.
My instructor invited me to join him in a process that he only does once or
twice a year at our public studio. I'm writing on his behalf.

Another instructor in our lab is questioning the safety of the firing we
did. They say it is unsafe and that we have permanently damaged the kiln
and we should dismantle the kiln used forever. Assuming that the salt
fuming is safe, this would be a shame as the results we achieved were truly
inspiring.

Please comment on the potential health hazards or let me know if what we
did is safe.

We loaded a saggar with our pots, organic materials, and salt. We put the
salt on the bottom of the saggar and we built trays within the saggar for
additional salt. We fired the propane fueled kiln to approx. cone 08 for
less than 5 hours. During the five hours the smoke does get heavy for a
while, but I thought that the harmful fumes burned off before they left the
kiln.

Help, we don't want to endanger anyone's health.

Thanks in advance,
Jules in Colorado where it's snowing in the high country in mid-June!

Earl Brunner on fri 19 jun 98

I doubt very much that the sodium firing damaged the kiln much if you can
detect no damage after a followup high fire. Salt kilns on the other hand,
build up a surface of sodium glaze in the inside surface of the kiln over a
period of time, and it actually takes less salt after several firings then it
did in the first few. Even if you did see damage to the kiln, as long as it
doesn't melt and continues to fire well and there are no adverse effects on
later pots, then why on earth would you take it apart and rebuild? Hysterical
reaction on the part of the others I think. On the other hand, there are
things you did not say in your post. Is the kiln soft brick or fiber and
therefore more susceptible to damage, is it inside a confined space, is there
ventalation, how bad were fumes, and how many were exposed? I suspect that the
organics gave off more of the noxious materials than the salt did. In our
studio, we have an old, small Geil kiln on wheels that is used exclusively for
this kind of firing. when ever it is fired, it is wheeled out side the door
and connected to the gas line and fired. It's old and beat up, but would
still probably work for other firings. The question most likely is, have you
coated the inside of the kiln with contaminants in such a way that other more
controlled firings will no longer work? If so, then others who share the use
of the kiln have a legitimate gripe.