Ron Roy on thu 18 jan 07
Hi everyone - especially those who work at cone 10 R and use a rutile blue
glaze.
I am working on a glaze for a potter up here in Onratio and he is having
pinholing problems - anybody had that problem - how did you fix it? Got a
recipe you can let me see so I can make some camparisons.
Please answer to my email address - and let me know if you don't want a
recipe published.
ronroy@ca.inter.net (Ron Roy)
I'll be glad to pass on any info to others about the problem if it's OK
with any who answer.
RR
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Edouard Bastarache Inc. on thu 18 jan 07
Ron,
check out my blog :
http://rutileblue.blogspot.com/
Later,
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
www.thepottersshop.blogspot.com
http://www.ceramique.com/cerambooks/rayons/technologie.php
http://www.flickr.com/photos/30058682@N00/
Ben Shelton on fri 19 jan 07
Ron,
Pinholes, blisters.. I'm not sure what to call tham but I have had that
problem for years on and off with this glaze.
custer feldspar 30
silica 26.3
epk 16.8
dolomite 15.8
whiting 11.1
rutile 4
red iron oxide 4
makes a nice, opaque, white glaze without the iron and rutile. I have fired
it on white bodies and on stoneware in reduction and got bubbles on both.
The bubbles seemed to haved formed when the glaze was semi fluid, burts and
the edges smoothed back over. Maybe this isn't even "pinholing" If not let
me know. I'd hate to add more complexity to your problem.
FWiw I always thought this glaze looked a bit overfired on the rims of pots.
The texture of the pot seemed to show through a bit much to me but the glaze
is so fluid that it runs off the pot.
I fired in solid reduction from about cone 08 on. and cleared on nuetral to
oxidsing for about 30 minutes at top temp.
Good luck, Ben
John Britt on sat 20 jan 07
Ron,
I don=92t know the answer but I have used rutile blue quite a bit and have
helped several friends fix their recipes, with mixed success.
I like this recipe, which is in my book page 109;
RUTILE BLUE 11
Cone 10
Custer Feldspar 30.00
Whiting 11.10
EPK Kaolin 16.80
Silica 26.30
Dolomite 15.80
Rutile 8.00
We tried everything from varying the clay body (About 10 clay bodies, from
porcelain, light stoneware to a dark porous stoneware and everything in
between), to different types of rutile including various batches of both
light and dark rutile, to different firings cycles with each, and
different cooling cycles.
The cure came from the firing cycle. It seemed that a light reduction was
the best. Emphasis on light. We also found that the 02 cycle was very good
but not too heavy on the peak reduction. A cooling soak can help but
slowing the firing at and around peak is best and watch the reduction!
The main problem is the inability to report the atmosphere of the kiln.
They would say that they fired in light reduction but they were firing in
medium or heavy reduction during various periods of the firing cycle and
not recording that. Everyone wanted to fire in heavy reduction just to
make sure everything was =93ok =93and this seemed to cause more pinholing. T=
he
test glazes fired along side the rutile pieces revealed the problem. (We
put tiles of copper red, shino and celadon in, on various bodies and they
revealed heavy reduction even though the person reported =93light
reduction=94.)
I don=92t know if this is the answer to your person=92s problem but I hope i=
t
helps you narrow it down. We spent about three months on this project.
Hope this helps and best to you,
John Britt
www.johnbrittpottery.com
Ron Roy on sun 21 jan 07
Hi Edouard,
Thanks!
RR
>Ron,
>
>check out my blog :
>
>http://rutileblue.blogspot.com/
>
>
>Later,
>
>
>
>Edouard Bastarache
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on thu 25 jan 07
Thanks Ben - RR
>Pinholes, blisters.. I'm not sure what to call tham but I have had that
>problem for years on and off with this glaze.
>
>custer feldspar 30
>silica 26.3
>epk 16.8
>dolomite 15.8
>whiting 11.1
>rutile 4
>red iron oxide 4
>
>
>
>makes a nice, opaque, white glaze without the iron and rutile. I have fired
>it on white bodies and on stoneware in reduction and got bubbles on both.
>The bubbles seemed to haved formed when the glaze was semi fluid, burts and
>the edges smoothed back over. Maybe this isn't even "pinholing" If not let
>me know. I'd hate to add more complexity to your problem.
>
>FWiw I always thought this glaze looked a bit overfired on the rims of pots.
>The texture of the pot seemed to show through a bit much to me but the glaze
> is so fluid that it runs off the pot.
>
>I fired in solid reduction from about cone 08 on. and cleared on nuetral to
>oxidsing for about 30 minutes at top temp.
>
>Good luck, Ben
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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