vince pitelka on tue 26 sep 00
> These items will always have a potential to leak because of a few things.
> 1. Poorly applied glaze on the interior
> 2. Poor choice of glaze for the interior.
> 3. Higly viscous nature of liquid paraffin and lamp oils.
Jonathan makes a good point here. This was discussed some time ago on
Clayart, and there is probably information in the archives. Even though
lamp oil seems thicker than water, it has a much greater ability to wick
through the crazing in the glaze and the porosity in the clay. Others on
the list could explain the physics of this no doubt (Evan?).
At NDSU in Fargo about eight years ago I had a student who made a series of
earthenware oil lamps, with the little beads to hold the glasswick. They
looked great, and he promptly filled one with lamp oil and we tried it out.
Worked beautifully. Left it in the studio for a few days, and he lit it
again during the next class. It sat just fine for a few minutes, and then
the flame started to spread down over the entire lamp housing. Needless to
say, if we had not noticed this quickly, the vessel would have heated up,
making the lamp oil far more volatile, and we would likely have had an
exciting incendiary event.
This can happen to a lesser degree even with high-fired oil lamps, again
dependent on the fit of the glaze and the porosity of the clay. It doesn't
take much and almost all high-fired clays have some porosity. So, if your
glaze is crazed on almost any body at any temperature, then you need to use
a lamp liner. However, if you can fill your high-fired oil-lamp reservoir
with lamp oil, and let it sit on a smooth surface for a week or two, and
then detect absolutely no sign of oil on the surface, then it is probably OK
without any liner.
Good luck -
- Vince
Vince Pitelka
Home - vpitelka@dekalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
http://www.craftcenter.tntech.edu/
John Baymore on wed 27 sep 00
At NDSU in Fargo about eight years ago I had a student who made a series =
of
earthenware oil lamps, with the little beads to hold the glasswick. They=
looked great, and he promptly filled one with lamp oil and we tried it ou=
t.
Worked beautifully. Left it in the studio for a few days, and he lit it
again during the next class. It sat just fine for a few minutes, and the=
n
the flame started to spread down over the entire lamp housing. Needless =
to
say, if we had not noticed this quickly, the vessel would have heated up,=
making the lamp oil far more volatile, and we would likely have had an
exciting incendiary event.
Great post, Vince.
He could always find a market for these mini "Molotov Cocktails" in some
trouble spot in the world . Good place to get rid of seconds
BTW...anyone making and selling oil lamps of any kind probably wants to
have a good product liability insurance policy in effect.
Best,
....................john
PS: Lots on last product liability insurance discussions in the archives=
..
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JBaymore@compuserve.com
John.Baymore@GSD-CO.com
"Earth, Water, and Fire Noborigama Woodfiring Workshop August 18-27,
2000"
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