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sv: leaky lamps!!

updated wed 15 apr 98


Isak Isaksson on tue 14 apr 98

-----Ursprungligt meddelande-----
Fren: wallace myers
Till: Multiple recipients of list CLAYART
Datum: den 13 april 1998 16:07
Dmne: Leaky lamps!!

>----------------------------Original message----------------------------
>Hi Folks:
> I made some oil lamps out of stoneware, glazed them
>inside and out and fired them to cone 6. I gave them to
>friends, who now tell me that they leak. What's going on?
>I thought that clay vitrified at cone 6 and should not leak
>even without glaze. If someone has a clue would you please
>inform me.

Hallo over there.
The oil you are using is probably `lampoil` made from / or just carrosine.
That kind of oil is used to find cracks in steel. The oil find it`s way in
smal cracks down to 10/ 1 mm, and if you fire a clay to C/6 it perhaps
become stoneware on the outside, but not in the middle. Not every clay
vitrifies at C/6, that depends on the parts in the clay!
Check the composition of the clay and fire to C/8-9

Isak /Sweden