Larry Kruzan on tue 9 feb 10
Are they worth the cost?
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
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William & Susan Schran User on wed 10 feb 10
On 2/9/10 11:06 PM, "Larry Kruzan" wrote:
> Are they worth the cost?
> Larry Kruzan
Larry,
The best answer is; it depends on your circumstances.
Some time back there was a long discussion about this on the crystalline
glaze discussion forum.
We crazies who have become addicted to crystalline glazes put a greater
demand on our kiln's elements more than most any other folks working in
clay.
But in our narrow little world, we have different circumstances and
different opinions. Most folks working in crystalline glazes fire to ^10,
usually with firing ramps faster than normal glaze firings, then extended
temperature holds in the 2000F range. Some of us fire to ^6, fairly fast,
then extended holds in the 1900F range.
For many using Kanthal A1 elements, in order to have the kiln maintain it's
scheduled firing program, elements are changed out every 30 - 40 firings.
Even a 10% difference, that would not be a big deal for most folks, can hav=
e
disastrous results in a crystalline firing. Others have conducted a cost
analysis and came to the conclusion that using heavy duty A1 elements and
having to change them once was cheaper than the added expense for APM
elements.
One of my colleagues stated that he gets 100 ^10 crystalline firings and
then installs the elements in other kilns to do ^5 glaze firings. You've
seen him and his Dad in ads for Skutt kilns.
I fire to only ^6 for my crystalline firings and have APM elements installe=
d
in my L&L e23S (23 diam. X 18H) and after 50 firings I have been able to
maintain my very aggressive firing schedules without any notable change.
Combined heating and cooling ramps results in firings lasting 15+ hours.
At school we have the same kiln and I had Stephen Lewicki owner of L&L wind
me some special elements. The elements are Kanthal A1, but are much heavier
than even their heavy duty elements. Don't recall if they are 12ga or 10ga,
but the pigtails were very difficult to bend. We use this kiln for
crystalline and "normal" ^6 firings and I expect them to last a very long
time.
One thing that is VERY important - after installing new elements one MUST
conduct a very slow breaking in firing in an empty kiln up to about ^5/6.
This firing settles the elements in the grooves and creates the protective
layer on the elements. If one does not do this, element life may be
shortened.
So that's what I got, hope it helps.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
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