Virgil and Susan Leise on thu 6 apr 00
------------------
Hi . I unloaded the kiln today..and still have a few pinholes=21When I =
talked with
the clay supplier...they suggested that I am wedging it wrong..putting air =
into
the clay...which causes the pinholes (they are there when I glaze ..before
firing the glaze) My question is this...Is there a site on the net that I =
can
see spiral wedging??? I have been doing pots for 20 years...my wedging
suddenly isn't good enough??? By the way...I have used other clay from =
other
suppliers...no problem?????? Tell me what you think ...PLEASE=21
Susan
Dannon Rhudy on fri 7 apr 00
At 02:22 PM 4/6/00 EDT, you wrote:
>----------------------------Original message----------------------------
>------------------
>Hi . I unloaded the kiln today..and still have a few pinholes!When I
talked with
>the clay supplier...they suggested that I am wedging it wrong..putting air
into
>the clay...which causes the pinholes (they are there when I glaze ..before
>firing the glaze) have used other clay from other
>suppliers...no problem?????? Tell me what you think ...PLEASE!
>Susan
>
----------------------------
I think your supplier is full of it. Even if you WERE
wedging "wrong" that would not cause pinholes in your glaze.
It may be that you are not taking enough time with your
bisque firing (you don't say that you once-fire, so I
am assuming not). In that case there MAY be some out-gassing
that is causing the pin-holes. Or it may be that there
is some difference in your glaze firing from previous
firings, or - have you changed glazes, or glaze ingredients?
If you BUY your glazes or glaze bases, has the supplier
made changes that you might be unaware of? Have you changed
the timing or ramping of your glaze fire? Have you tried
re-firing to see if the pinholes "heal"? Or, are they
worse? You need to know those things, to help you solve
the problem. But don't waste time worrying that you're
suddenly somehow wedging in a way that causes pinholes.
regards
Dannon Rhudy
potter@koyote.com
Hank Murrow on fri 7 apr 00
>----------------------------Original
>message---------------------------->Hi . I unloaded the kiln today..and
>still have a few pinholes!When I talked with
>the clay supplier...they suggested that I am wedging it wrong..putting air
>into
>the clay...which causes the pinholes (they are there when I glaze ..before
>firing the glaze) My question is this...Is there a site on the net that
>I can
>see spiral wedging??? I have been doing pots for 20 years...my wedging
>suddenly isn't good enough??? By the way...I have used other clay from other
>suppliers...no problem?????? Tell me what you think ...PLEASE!
>Susan
Well; Unless someone is pulling your leg, the response and instruction you
received Susan is just plain wrong. Sort of like when harried teachers(in
too much haste) told you that the 'air bubbles' caused it to blow up in the
bisque. Usually very small pits in the freshly glazed surface will heal if
given enough soak in the glaze firing. Sometimes, if the clay has lots of
combustibles(sulphates & the like), and the bisque is too low to burn them
out completely; one can get pinhole from escaping gasses during the glaze
fire. Try soaking your kiln an hour or so longer without going past your
end-cone, and see if the pinholes disappear. Hank in Eugene
Earl Brunner on sat 8 apr 00
I think it's a bunch of crock! (hehehe) They are trying to
divert you.
Virgil and Susan Leise wrote:
>
> ----------------------------Original message----------------------------
> ------------------
> Hi . I unloaded the kiln today..and still have a few pinholes!When I talked wi
> the clay supplier...they suggested that I am wedging it wrong..putting air int
> the clay...which causes the pinholes (they are there when I glaze ..before
> firing the glaze) My question is this...Is there a site on the net that I ca
> see spiral wedging??? I have been doing pots for 20 years...my wedging
> suddenly isn't good enough??? By the way...I have used other clay from other
> suppliers...no problem?????? Tell me what you think ...PLEASE!
> Susan
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
David Hendley on sat 8 apr 00
I can't prove it, but I sure don't think that wedging has
any effect on pinholes in glazes.
Some suggestions:
Try smoothing over the holes in the raw glaze by just
rubbing it with your hand.
Try bisque firing a little hotter.
Try bisque firing slower, with a short soak period at the end.
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
----- Original Message -----
From: Virgil and Susan Leise
To:
Sent: Thursday, April 06, 2000 1:22 PM
Subject: Pinholes and wedging
----------------------------Original message----------------------------
------------------
Hi . I unloaded the kiln today..and still have a few pinholes!When I talked
with
the clay supplier...they suggested that I am wedging it wrong..putting air
into
the clay...which causes the pinholes (they are there when I glaze ..before
firing the glaze) My question is this...Is there a site on the net that I
can
see spiral wedging??? I have been doing pots for 20 years...my wedging
suddenly isn't good enough??? By the way...I have used other clay from
other
suppliers...no problem?????? Tell me what you think ...PLEASE!
Susan
Paul Taylor on sat 8 apr 00
Dear Susan
In the archive you will find several letters dispelling the rumors of
air trapped in the clay causes problems in firing. The only problem air
causes in clay is to upset the centrifuge of the clay when throwing, making
it difficult to center and the build up of steam in such as a knob or rolled
rim causing explosions in the biscuit firing.
If air was a problem ,on a regular basis, you would find throwing almost
impossible to do with satisfaction. and you would feel the air and see it in
the wall of the pots.
All glazes form pinholes when glazing some more than others especially
if they have been vigorously stirred- Just rub them over with a finger. If
it happening a lot check that the glaze is stable some materials liberate
oxygen and some additives set off eutrification that produces carbon
bubbles; which land on the pots as pinholes.
Ideally the glaze should contain the minimum amount of water for the
amount of fluidity in the glaze. Defloculated gazes particles flow into the
biscuit so much better preventing crawling and pinholes, but a glaze that
runs into beads around the pot and one that you have to stir every five
minuets is also a hassle. A happy medium has to be found. Most glazes
naturally defloculate in the bucket. If your pinholing occurred in a new
bucket of glaze that is a clue to let it settle and defloculate naturally.
Matt glazes that have a high viscosity or little flow (believe it or not
they are not the same) have a tendency to pinhole and at worst crawl. You
have to be extra diligent with these glazes smoothing over the holes after
glazing.
Also Glazes On top of a body where the carbon has not been burnt out on
the biscuit firings. The inside of the shapes will be more pinholed than the
out and the holes will look bubbly, this is called blistering or boiling.
And bits of organic matter like wood dust or fibers on/in the surface
of the pot. The organic matter leaves a small unnoticeable hole in the pot,
that on glaze firing the glaze does not heal over .
If you are using titanium or one of its forms rutile etc you have got a
real problem . I gave up using these because I could no longer bear the
pinholing. It worked well for years THEN PINHOLED. I suspected the firing .
I thought that a long oxidized soak that I had introduced was having a bad
effect or was it the time or length of the reduction , or was it the firing
or cooling cycle . The more efficiently I fired the worse it got but it
could have been any thing. Mostly the glaze came out great but occasionally
it would throw a wobbler and I would get pinholing . I could not afford to
find out why. So I changed every thing- and for the better.
If it is a titanium glaze you are fighting with you will need very
specific advise from a person with expertise with the material or very
specific methodology from someone that got lucky. Again I reflect that I may
have had a change from a carbonate to a oxide of titanium. I may have been
using too much. Was I at the maximum amount? Was It the reduction?
I have a feeling that the odd pinhole is sent to try us especially in a
thick opalescent glaze . I am more tolerant of it than crazing and will
quite happily sell the pieces as seconds.
As with all problems one of these may not be the single cause but you
may have a combination of them all.
Regards Paul T
----------
>From: Virgil and Susan Leise
>To: CLAYART@LSV.UKY.EDU
>Subject: Pinholes and wedging
>Date: Thu, Apr 6, 2000, 7:22 pm
>
>----------------------------Original message----------------------------
>------------------
>Hi . I unloaded the kiln today..and still have a few pinholes!When I talked wit
>the clay supplier...they suggested that I am wedging it wrong..putting air into
>the clay...which causes the pinholes (they are there when I glaze ..before
>firing the glaze) My question is this...Is there a site on the net that I can
>see spiral wedging??? I have been doing pots for 20 years...my wedging
>suddenly isn't good enough??? By the way...I have used other clay from other
>suppliers...no problem?????? Tell me what you think ...PLEASE!
>Susan
Earl Brunner on sun 9 apr 00
If the pinholeing is occuring in an area that has been
trimmed, you might
need to burnish the trimmed area with a tool after
trimming. I've noticed
that some glazes seem to pinhole in trimmed areas.
David Hendley wrote:
>
> ----------------------------Original message----------------------------
> I can't prove it, but I sure don't think that wedging has
> any effect on pinholes in glazes.
> Some suggestions:
> Try smoothing over the holes in the raw glaze by just
> rubbing it with your hand.
> Try bisque firing a little hotter.
> Try bisque firing slower, with a short soak period at the end.
>
> --
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com/
>
> ----- Original Message -----
> From: Virgil and Susan Leise
> To:
> Sent: Thursday, April 06, 2000 1:22 PM
> Subject: Pinholes and wedging
>
> ----------------------------Original message----------------------------
> ------------------
> Hi . I unloaded the kiln today..and still have a few pinholes!When I talked
> with
> the clay supplier...they suggested that I am wedging it wrong..putting air
> into
> the clay...which causes the pinholes (they are there when I glaze ..before
> firing the glaze) My question is this...Is there a site on the net that I
> can
> see spiral wedging??? I have been doing pots for 20 years...my wedging
> suddenly isn't good enough??? By the way...I have used other clay from
> other
> suppliers...no problem?????? Tell me what you think ...PLEASE!
> Susan
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Andie on sun 9 apr 00
I had this problem for a long time, and couldn't figure out why. I read
everything I could find about firings, and finally consulted with the "glaze
guru" at a nearby college. He told me my clay body was particularly high in
carbon, and to soak my bisque firing and leave the peepholes open. I
experimented, and found that with Standard's 108, 181, and 153, if I soak at
5 (on an electric kiln) for three hours before moving up to 7 and then high,
I very, very rarely have pinholes. Also, I switched from bisque firing at 06
to 04, this seems to contribute to success as well. Maybe you could try
soaking your kiln during the bisque. I don't wedge my clay, though, just cut
from the bagged clay I buy, so I don't think wedging has anything to do with
it.
Andie
-----Original Message-----
From: Earl Brunner
To: CLAYART@LSV.UKY.EDU
Date: Saturday, April 08, 2000 6:03 PM
Subject: Re: Pinholes and wedging
>> ----------------------------Original message----------------------------
>> ------------------
>> Hi . I unloaded the kiln today..and still have a few pinholes!When I
talked wi
>> the clay supplier...they suggested that I am wedging it wrong..putting
air int
>> the clay...which causes the pinholes (they are there when I glaze
..before
>> firing the glaze) My question is this...Is there a site on the net that
I ca
>> see spiral wedging??? I have been doing pots for 20 years...my wedging
>> suddenly isn't good enough??? By the way...I have used other clay from
other
>> suppliers...no problem?????? Tell me what you think ...PLEASE!
>> Susan
Chris Schafale on tue 11 apr 00
To tack on to this suggestion, I've found it helps tremendously if,
immediately after trimming, I coat the trimmed areas with a little
slip from the throwing bucket (use a wide brush), then remove the
wet stuff/burnish lightly with a soft rubber rib. This fills in the grog
holes/scratches and prevents pinholes later.
I forget who said this first, so can't give credit, but I'm pretty sure
this was another clayart gem. Thanks!
Chris
> ----------------------------Original message---------------------------- > If
pinholeing is occuring in an area that has been > trimmed, you
might > need to burnish the trimmed area with a tool after >
trimming. I've noticed > that some glazes seem to pinhole in
trimmed areas. >
Light One Candle Pottery
Fuquay-Varina, North Carolina, USA
(south of Raleigh)
candle@intrex.net
http://www.lightonecandle.com
| |
|
