vince pitelka on fri 16 feb 01
> I have been approached to produce some classical era oil lamps for an
olive
> oil producer. My research suggests that some lamps had, what one source
> calls, a black glaze liner to prevent oil saturating the terracotta body
of
> the lamp. It is my understanding that the Ancient Greeks actually did not
> use glaze as we understand it, but a black "terrasigilata" and that the
> method for producing that colour is still unknown. Can any one confirm
this
> and or make suggestions for a black low fire liner for these items.
Feri -
The domestic Roman oil lamps were just terra sig coated, which should give a
fairly impervious finish. Also, in the process of conquering the known
world the Romans adopted irridescent lead glazes from the Middle East, and
you could substitute a similar alkaline formula to seal the inside.
The black decoration on ancient Greek pottery is just the same slip as the
red decoration, but it has been fluxed with a strong alkaline solution made
from wood ashes. In a reduction firing all the slips turn black, but when
the firing is stopped at exactly the right time, the black slip has
vitrified slightly, due to the increased flux content, and therefore the
reduced black iron oxide is locked in place. The red slip is less
refractory, and it reoxidizes to red iron oxide. Seems that most
technicians who have studied ancient Greek red black wares pretty much agree
on this.
I am not sure what you have in mind for these oil lamps, but I should point
out that an oil lamp with a poorly sealed surface is a bit dangerous. The
oil can soak in through the unsealed surface, and eventually the whole lamp
can begin to act as one big wick.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
ferenc jakab on fri 16 feb 01
I have been approached to produce some classical era oil lamps for an olive
oil producer. My research suggests that some lamps had, what one source
calls, a black glaze liner to prevent oil saturating the terracotta body of
the lamp. It is my understanding that the Ancient Greeks actually did not
use glaze as we understand it, but a black "terrasigilata" and that the
method for producing that colour is still unknown. Can any one confirm this
and or make suggestions for a black low fire liner for these items.
Feri.
Remember I'm living in Australia. I don't have access to U.S. suppliers.
Earl Brunner on fri 16 feb 01
Made some Palestinian terra cotta oil lamp reproductions for a program
the young women in our church were doing. Since they weren't museum
pieces and I figured someone was going to try and us them (they did). I
just took a cone 06 clear glaze, watered it down and coated the inside
with that. It seamed to seal them very well.
ferenc jakab wrote:
> I have been approached to produce some classical era oil lamps for an olive
> oil producer. My research suggests that some lamps had, what one source
> calls, a black glaze liner to prevent oil saturating the terracotta body of
> the lamp. It is my understanding that the Ancient Greeks actually did not
> use glaze as we understand it, but a black "terrasigilata" and that the
> method for producing that colour is still unknown. Can any one confirm this
> and or make suggestions for a black low fire liner for these items.
> Feri.
>
> Remember I'm living in Australia. I don't have access to U.S. suppliers.
>
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Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Lili Krakowski on fri 16 feb 01
As we were not there, we willnever know what impermeability the black
liner supplied. I would bet not much. in my personal opinion impermeab
le earthenweare is an oxymoron. After time all non vitrified clay absorbs
liquid. The less porosity he slower he absorption. However for color
effect you might try a lower-yet-firing clay
like something you can dig up yourself; or get some low fired clay and add
some add, plain bicarb or soda ash and see what happens. Adding iron
oxide also may help, with color.
Lili Krakowski
Paul Taylor on fri 16 feb 01
Dear Earl
If you make up a terrasigalata out of red clay reduce the kiln while the
terasig is fluxing up to the point it has fired to its optimum do not over
do it or it will disappear and then reoxidize - the clay will go red and the
red terrasigalata will be the new black- you will have to do some tests .
It is possible I have done it. However I do not know if the surface is
totally water proof. Go to the Digifire site for a good recipe . The red
clay you use may also make a difference . I can only vouch for the color.
Regards from Paul Taylor
http://www.anu.ie/westportpottery
Alchemy is the proof that economics is not a science.
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