Ben on thu 11 nov 04
Mornin'
I guess the subject says most of it. I'm looking for suggestions to =
minimize air bubbles/pinholing dipping glaze. I bisque at 04 fairly =
typical stoneware glazes. Seems like sometimes I get them and sometimes =
I don't.
Thanks Ben
Ivor and Olive Lewis on fri 12 nov 04
Ben,
Inspect your pots well after you have dipped them. You should be able
to fettle any pinholes in the raw glaze at that stage.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Rogier Donker on fri 12 nov 04
on 11/12/04 8:40 PM, Lee Love at lee@MASHIKO.ORG wrote:
> Ben wrote:
>
>> Mornin'
>> I guess the subject says most of it. I'm looking for suggestions to minimize
>> air bubbles/pinholing dipping glaze. I bisque at 04 fairly typical stoneware
>> glazes. Seems like sometimes I get them and sometimes I don't.
>> Thanks Ben
>>
>
> Ben, If you wet-sponge your bisque just before glazing, it can get
> rid of some pinholing problems. Also, after glazing, you can rub out
> the small pinholes and fill-in the larger ones with a small brush.
>
> --
> Lee in Mashiko, Japan http://mashiko.org
> http://www.livejournal.com/users/togeika/ WEB LOG
> http://public.fotki.com/togeika/ Photos!
>
Ben!
Sounds like sometimes your glaze might be too thick a consistency...use a
hydrometer to measure the SG of the glaze for consistent results...after a
while you just KNOW what is too thick or too thin...
Rogier
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Lee Love on sat 13 nov 04
Ben wrote:
>Mornin'
>I guess the subject says most of it. I'm looking for suggestions to minimize air bubbles/pinholing dipping glaze. I bisque at 04 fairly typical stoneware glazes. Seems like sometimes I get them and sometimes I don't.
>Thanks Ben
>
Ben, If you wet-sponge your bisque just before glazing, it can get
rid of some pinholing problems. Also, after glazing, you can rub out
the small pinholes and fill-in the larger ones with a small brush.
--
Lee in Mashiko, Japan http://mashiko.org
http://www.livejournal.com/users/togeika/ WEB LOG
http://public.fotki.com/togeika/ Photos!
Ron Roy on sun 14 nov 04
Hi Ben,
The craters you see after glazing are not usually the cause of pin holes by
the way - it is usually gas escaping from the body or the glaze - forming
bubbles that do not have a chance to heal over.
Make sure you fire your bisque slow enough and with plenty of oxygen
present to get all the burnables out - bisque to cone 04.
Soak long enough to let any stiff glazes smooth out - or adjust them to
flow a bit better.
Cool slower from the top temp to again let the glaze heal over.
If you want me to look at the glazes - to see if they are too stiff send
them to me at ronroy@ca.inter.net.
If you refire and the pinholes are still there or get worse it's probably
your bisque firing. If a refire gets rid of them have the glazes adjusted.
RR
>Mornin'
>I guess the subject says most of it. I'm looking for suggestions to
>minimize air bubbles/pinholing dipping glaze. I bisque at 04 fairly
>typical stoneware glazes. Seems like sometimes I get them and sometimes I
>don't.
>Thanks Ben
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ben on sun 14 nov 04
Hi Ron,
The ones I'm trying to address here are the ones formed in the raw glaze
coat at the time of dipping. I usually just rub them over as some have
mentioned. But would prefer to minimize them at the time of application. I
do bisque to 04. I'm a little slack about S.G. I try to mix by eye and
then weigh to verify but I leave a little range in adjusting. I'm usally
content with a range between 1.4 and 1.45 if it looks right. But like I
said sometimes I get them and sometimes I don't. It does seem like some
glazes are more prone than others but I haven't intuited the cause yet.
It seems like my firing blisters were caused by too little time in the
volatiles burnout range(1000-1600F). So I slowed down in that range, use
smaller orifices and higher pressure (in that range) to get a better(more
oxidized) flame and keep my damper wide. Seems like it's helping, so far.
Ben
Ron Roy on tue 16 nov 04
Hi Ben,
Sounds like the glaze or glazes are not melting properly - You can try
reducing the clay in the recipe - just do a short line blend reducing the
clay by 1 each time.
You can also vibrate the glaze to get the bubbles out - bang the bucket for
instance - and try not to entrain air when you are stirring - you will
still get some bubbles though.
RR
>Hi Ron,
>The ones I'm trying to address here are the ones formed in the raw glaze
>coat at the time of dipping. I usually just rub them over as some have
>mentioned. But would prefer to minimize them at the time of application. I
>do bisque to 04. I'm a little slack about S.G. I try to mix by eye and
>then weigh to verify but I leave a little range in adjusting. I'm usally
>content with a range between 1.4 and 1.45 if it looks right. But like I
>said sometimes I get them and sometimes I don't. It does seem like some
>glazes are more prone than others but I haven't intuited the cause yet.
>
>It seems like my firing blisters were caused by too little time in the
>volatiles burnout range(1000-1600F). So I slowed down in that range, use
>smaller orifices and higher pressure (in that range) to get a better(more
>oxidized) flame and keep my damper wide. Seems like it's helping, so far.
>
>Ben
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
May Luk on wed 17 nov 04
Hiya;
I made the same observation the day before Ben asked his question. When I
make my test tile, the part that's double dipped get pinholes on the raw
glaze - mostly on stoneware clay; porcelain is not a problem. I usually
ignore it cause it's only a test. I don't really double dip in actual
glazing. Also I found that if the glaze is a bit thin, it gets the bubble
effects if it stays on longer than normal. It has to do with air
displacement, I suppose.
May
London
UK
Jim Smola on wed 17 nov 04
I just had this same issue and found there were two things that eliminated
it.
I now bisquet one cone hotter (thank you Roy!); and after stirring the
glazes I now "tap" the sides of the buckets a few times before dipping--I've
not had any of the small pinholes since.
The Pottery Pimp
Jaymes
http://www.werhandmaid.com
----- Original Message -----
From: "May Luk"
To:
Sent: Wednesday, November 17, 2004 4:10 PM
Subject: Re: raw glaze pinholes/air bubbles
> Hiya;
>
> I made the same observation the day before Ben asked his question. When I
> make my test tile, the part that's double dipped get pinholes on the raw
> glaze - mostly on stoneware clay; porcelain is not a problem. I usually
> ignore it cause it's only a test. I don't really double dip in actual
> glazing. Also I found that if the glaze is a bit thin, it gets the bubble
> effects if it stays on longer than normal. It has to do with air
> displacement, I suppose.
>
> May
> London
> UK
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
| |
|
