Hank Murrow on sat 17 mar 12
85.?=3D
My friend, Rosette gault has sent me this answer to the question raised =3D
earlier concerning warnings of corrosive effects of firing paperclay in =3D
electric kilns. Posted here from Rosette, courtesy of Hank:
http://www.paperclayart.com/181firinginkilns.html
Firing (P'Clay) in Electric and other Kilns: About Fumes and Timing
The sulphuric and other burnout fumes from any clay firing should be =3D
ventilated, paper or not. Paper fiber exits the clay body (451F/253C), =3D
early on in the fire, similar to like wax burnoff that is before cone =3D
032 will melt. The process finishes in the first several hours of an 8 =3D
hour fire going to bisque 1000C or higher. The combustion smoke and =3D
moisture exiting does not hurt the electric wire kiln elements in a dark =
=3D
slow heating kiln (451F/253C). Indeed the amount of paper in paperclay =3D
adds up to less than the handfuls of raw crumpled paper sometimes used =3D
to support handbuilt structures.
It is unwise to put dry paper or other combustibles directly into a red =3D
hot (around 1000C 1850F and up) electric kiln. Superheated gas ignites =3D
the paper instantly. Too much fuel all of a sudden, and not enough =3D
oxegen so creates a red hot smoke. Ultra hot smoke (from incomplete =3D
combustion reducing atmosphere) will corrode electric wireheating =3D
elements over time and shorten thier life. Also radical temperature =3D
changes will stress heating elements- which is why most do not raku with =
=3D
electric kilns. Presence of paper or other combustibles in an electric =3D
kiln at glowing red heat is not recommended.
By the time the kiln temperature reaches (1000C 1850F or so) internal =3D
paper pulp fiber has been absent for hours, having exited the clay at =3D
F451/C253 degrees and can't, therefore, cause reduction, nor a =3D
superheated gas just explained.
My book, and others, have full firing schedules to guide you in learning =
=3D
curve.
Take some clay classes and really get practice with firings before =3D
investing in kilns. There is no substitute for direct experience. And =3D
there are many variations in paperclay, user experience, kilns, I can't =
=3D
be responsible for errors. Test fire is always a great practice whatever =
=3D
kind of clay you like.
There is much more about paperclay- on my site. I welcome NCECA visitors =
=3D
to Seattle, to come find me and say hi. I will be at the WCAA =3D
(Washington Clay Artist Association) table Wed March 28, 2011 at 9-11, =3D
and Thurs March 29, 1:30-3. There is a show opening Wed afternoon, and a =
=3D
studio demonstration just before that, find up to date notes on the =3D
calendar section of my site www.paperclayart.com or =3D
www.rosettestudio.net. A mailing is about to go out- please sign up at =3D
the link below- if you would like this.
Rosette=3D20
Some Works On View in Seattle March 2012=3D20
Rosette Ceramic Works =3D20
Be Part of My World=3D20
Join My Mailing List
| |
|
