[Clayart] Hole in the bottom of a bowl on a potter's wheel

[wschran at twc.com]

Using slip instead of water would not cause the problem you describe.
>From what you wrote it appears you are creating a void at the center of the bottom of cone of clay.
Is the bottom of the cone flat or rounded?
If it is flat the void can happen when you attach to wheel.
Try rolling the bottom of the cone into a rounded shape then attaching firmly to wheel.
With wheel turning very slow, using no water or slip, slap the cone all around bringing the edge down to wheel head and seal the edge with your finger.

Bill

William Schran
wschran at twc.com
703-505-1617

---- Vlasova Tatiana <yanatt at gmail.com> wrote: 
> Thank you, William
> Usually I throw clay on a wheel in the cone with a round bottom, and I
> press (lower) it from above, but not along the edges below.
> I'll see to it that I press it down near the wheel.
> Thank you!
> 
> I centering pieces more than 3kg so slowly and long time, and instead of
> water I use a slip for wetting. Can a slip or a long centering create a
> problem with a bubble in the bottom?
> 
> 2018-05-19 13:06 GMT+03:00 <wschran at twc.com>:
> 
> > This may have been from when the clay was attached to the wheel head or
> > bat.
> > The shape of the bottom of the clay may have had a small depression or
> > void from wedging.
> > Have the bottom of the clay that will be attached to wheel head curved to
> > avoid this.
> >
> > bill
> >
> > William Schran
> > wschran at twc.com
> > 703-505-1617
> >
> > ---- Vlasova Tatiana <yanatt at gmail.com> wrote:
> > > Hello! Can I ask for advice for novice potter?
> > I make a bowl 28-30 cm, and when I remove it from the wheel, there are no
> > air bubbles, there is no hole at the bottom. But when the bowl dries, the
> > hole forms from the outside downwards in the center. Where the bottom
> > touched the wheel. Not cross-cutting
> > As if the clay in this place was more wet and sat down more.
> > When I cut the bottom, I removed this hole. But I do not understand why
> > this is happening?
> >
> > many thanks
> > Tanya
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