gwalker on mon 15 mar 99
------------------
G'day Claybugs,
I need your help=21 Why, suddenly, would a normally well-behaved cone 10
copper red glaze start to crawl? This glaze is erratic, it's colour
appearing to be dictated by the weather on firing days (more of that
later =85), but it has never been a crawler. Two glaze batches have been
mixed this past two weeks, and both of them are behaving this way. Both
batches were mixed from bulk bags we have used previously with no
problems, so it is not due to a variation in the ingredients.
The crawling is strange =85 some appearing as if the glaze coat has pulled
away from the edges of the wax foot, but on other pots (mostly mugs)
there are white areas, still with a thin coating of glaze, where the
surface seems to have drawn back on itself. On a couple of water jugs
there are areas as large as 3=22 x 3=22 where the glaze has crawled back so
thickly that it has turned into a stalactite and become a thick dribble,
running down over the shelves.
There is no evidence of crawling on the insides of bowls or plates (the
outsides have a different glaze). The problem is worse where the pots
have been turned, initially begging the question of a role for dust, but
it has occurred on handles as well.
Before I take to throwing myself off the top of the Marriott (the rate
my luck is going these days I would probably fly=21), could some kind guru
point my tired brain in the right direction? I'm lost and depressed =85
not like me at all=21
TIA
Geoff, on the Gold Coast, experiencing another perfect day =85
weatherwise, at least=21 =3B-)
http://www.cronulla-pot.com.au/
Louis on tue 16 mar 99
Dear Crawling,
1. Too fast of a preheat in the glaze fire can casue crawling. This causes
problems for us, but only in already troublesome glazes.
2. Soluble salts in the water source seems to be a cause down where I live.
3. Scumming on the clay
4. Dirty bisque, dust, grease, fingerprints, Try wiping the pots with a
damp sponge first.
Louis
--
Louis Katz, mailto: lkatz@falcon.tamucc.edu
The Island University
National Council on Education for the Ceramic Arts (NCECA)
Traditional Thai Pottery Video, Guide and Dictionary, Melted Man
Productions
Merrie Boerner on tue 16 mar 99
Hey Geoff,
This crawling happened to me once so I went down the check list of
possible causes........couldn't figure it.....Then, one day while putting
lotion on my hands, I realized that I must have tainted my bisque ware with
Vaseline Intensive Care ! The pots were still porous enough to accept the
glaze......and looked clean to me......but, underneath was a slippery
culprit !
I keep the lotion in the house, now. So, Geoff.....Who's been patting
your pots ? : ) Merrie
Tom Wirt on tue 16 mar 99
Subject: Re: New crawling problem! Urgh!
>----------------------------Original message----------------------------
>Hi, Geoff,
>I don't know if this will work for you or not, but I have stopped
>crawling in a number of my glazes by mixing them up with lots of water,
>adn siphoning it off. I do this at least twice before I use them. I
>have no idea why this should work, but it sometimes does. Probably
>something soluble in the glaze.
>Paul Lewing, signing off Clayart to go to NCECA. Be back Sunday.
Paul...If I read Ron Roy right, the hypothesis for this "washing" of a glaze
gets the salts out. If they are left in the glaze, as they volatize at
relatively low temps, they can push the glaze off the surface. Wonderful
things these little molecules.
Tom Wirt
Paul Lewing on tue 16 mar 99
Hi, Geoff,
I don't know if this will work for you or not, but I have stopped
crawling in a number of my glazes by mixing them up with lots of water,
adn siphoning it off. I do this at least twice before I use them. I
have no idea why this should work, but it sometimes does. Probably
something soluble in the glaze.
Paul Lewing, signing off Clayart to go to NCECA. Be back Sunday.
Tom Wirt on tue 16 mar 99
>>>>>From: gwalker
>>>>Subject: New crawling problem! Urgh!
I need your help! Why, suddenly, would a normally well-behaved cone 10
copper red glaze start to crawl?<<<
Not being able to see the glaze formula, but after what we've been through
the last 4 months with the infamous moonlight, and lots of help from Ron
Roy, David Hendley, Tom Buck and others, my first guess would be that
you've got too much water in the glaze slop.
Do you use Epsom Salts or other flocculent to thicken the glaze. Is the pH
alkaline?
Try letting it settle, taking off as much water as possible, and then
deflocculating with Darvan 7 or other deflocculant to a workable viscosity.
One of many causes of crawling.
Tom Wirt
eden@sover.net on thu 18 mar 99
I also had this happen, I can testify! I lotioned up my hands just before
pouring a large urn. HUGE crawls all around the inside of the neck, cause
absolutely obvious. Boy did I feel stupid. Big problem, simple solution.
Eleanora
At 08:42 PM 3/16/99 -0500, you wrote:
>----------------------------Original message----------------------------
>Hey Geoff,
> This crawling happened to me once so I went down the check list of
>possible causes........couldn't figure it.....Then, one day while putting
>lotion on my hands, I realized that I must have tainted my bisque ware with
>Vaseline Intensive Care ! The pots were still porous enough to accept the
>glaze......and looked clean to me......but, underneath was a slippery
>culprit !
> I keep the lotion in the house, now. So, Geoff.....Who's been
patting
>your pots ? : ) Merrie
>
Eleanora Eden 802 869-2003
Paradise Hill
Bellows Falls, VT 05101 eden@sover.net
Beth Ward on thu 18 mar 99
In a message dated 3/17/99 3:51:21 AM Pacific Standard Time,
claypot@hutchtel.net writes:
<< Paul...If I read Ron Roy right, the hypothesis for this "washing" of a
glaze
gets the salts out. If they are left in the glaze, as they volatize at
relatively low temps, they can push the glaze off the surface. Wonderful
things these little molecules. Tom Wirt
>>
This post just saved me a whole lot of time and money.... I am going to try
this with 4 -5 buckets of glaze that have not been playing nicely on pots
lately.
Beth
John Britt on fri 19 mar 99
Beth,
I hate to disagree with Ron Roy or Tom Wirt, but I don't know if this
"solution" of "washing out glazes" is always a good idea.
You are pouring out any water soluble ingredients. It may be good if
you have small amounts of alkali that are causing problems but it will
not work in the case of many shinos. For example Malcom's shino
contains around 19% soda ash. You cannot pour the water off without
seriously effecting the glaze. The glaze will be entirely different.
Basically it will be a matt off white opaque ugly glaze. Rather than a
excellent carbon trap shino. This would have a similar effect on any
shino (glaze) with soda ash in it. You are pouring it out.
Just a word of caution.
----------------------------Original message----------------------------
In a message dated 3/17/99 3:51:21 AM Pacific Standard Time,
claypot@hutchtel.net writes:
<< Paul...If I read Ron Roy right, the hypothesis for this "washing" of
a
glaze
gets the salts out. If they are left in the glaze, as they volatize at
relatively low temps, they can push the glaze off the surface.
Wonderful
things these little molecules. Tom Wirt
>>
This post just saved me a whole lot of time and money.... I am going to
try
this with 4 -5 buckets of glaze that have not been playing nicely on
pots
lately.
Beth
--
Thanks,
John Britt claydude@unicomp.net
Dys-Functional Pottery
Dallas, Texas
http://www.dysfunctionalpottery.com/claydude
Sharon Pollock-De Luzio on fri 26 mar 99
Soluble salts causing crawling. INTERESTING. I suppose that's why shino's
crawl. Also the effect of water content, bisquing low and
absorption/compression of glaze materials onto bisque surface......
I've noticed that if I want to double dip my shino I need to do it almost
immediately or it crawls too much.
Thanks to all for explaining this stuff. Keep up the good work.
Sharon in RI
| |
|
