James Myers on thu 23 aug 07
I've been using a kiln wash of 50 / 50 EPK and silica. I fire to cone 10 in
a 64 cubic foot gas kiln. I have high alumina and silicon carbide shelves
and the kiln was flakes off both types of shelves every time. I don't know
what the issue is. I scrape and sponge the shelves after every firing before
I use the wash. Any insight into this dilemma would be greatly apriciated.
Thanks
--James
Gordon Ward on thu 23 aug 07
You might try dry alumina hydrate instead. You never have to worry
about flaking. I used to brush it off the shelves into a pan and
then reapply with a shaker when stacking, but now I just reverse
stack the shelves next to the kiln, leaving the powdered surface
alone. If you rally want to use a wash, reduce the amount of clay
and put it on thin.
Gordon
On Aug 23, 2007, at 12:06 PM, James Myers wrote:
> I've been using a kiln wash of 50 / 50 EPK and silica. I fire to
> cone 10 in
> a 64 cubic foot gas kiln. I have high alumina and silicon carbide
> shelves
> and the kiln was flakes off both types of shelves every time. I
> don't know
> what the issue is. I scrape and sponge the shelves after every
> firing before
> I use the wash. Any insight into this dilemma would be greatly
> apriciated.
>
> Thanks
> --James
Gayle Bair on thu 23 aug 07
James,
How thick do you apply the wash?
I'm firing in a 7 cu ft electric kiln and
I am not an expert but the only time
I have seen kiln wash flaking off in electric
or gas kilns is when it's applied way too thick.
Gayle Bair
Bainbridge Island, WA
Tucson, AZ
http://claybair.com
-----Original Message-----
From: James Myers
I've been using a kiln wash of 50 / 50 EPK and silica. I fire to cone 10 in
a 64 cubic foot gas kiln. I have high alumina and silicon carbide shelves
and the kiln was flakes off both types of shelves every time. I don't know
what the issue is. I scrape and sponge the shelves after every firing before
I use the wash. Any insight into this dilemma would be greatly apriciated.
Thanks
--James
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Ann Brink on thu 23 aug 07
If you start using 50/50 EPK and Alumina, you will be much happier! It
won't flake, and you can leave it alone for ages, occasionally adding a few
brush strokes of the mixture on top of the old. Can you tell I am a convert?
Ann Brink in Lompoc CA
(mostly about pottery)
----- Original Message -----
From: "James Myers"
> I've been using a kiln wash of 50 / 50 EPK and silica. I fire to cone 10
> in
> a 64 cubic foot gas kiln. I have high alumina and silicon carbide shelves
> and the kiln was flakes off both types of shelves every time. I don't know
> what the issue is. I scrape and sponge the shelves after every firing
> before
> I use the wash. Any insight into this dilemma would be greatly apriciated.
>
> Thanks
>
John Post on thu 23 aug 07
I use Lee's Amazing Kiln Wash from Axner pottery.
I fire two kilns 3 times a week as an art teacher and I hate messing
around with kiln wash.
With Lee's you scrape the old wash off, brush Lee's on and it stays
put. No Flaking.
I only do touch up to my 15 shelves at the beginning of the school year.
If a glaze blob gets on the shelf I just whack it with a chisel and it
pops right off.
This stuff is around $50 bucks a gallon.
The best part though is that my kiln room floor isn't covered in flakes
of kiln wash. Neither are my kilns.
This stuff stays on the shelves.
It may seem pricey but it makes up for it in all the time you save not
messing around with flaky wash.
http://www.axner.com/axner/equipment/lees-kiln-wash.php
John Post
Sterling Heights, Michigan
>I've been using a kiln wash of 50 / 50 EPK and silica. I fire to cone 10 in
>a 64 cubic foot gas kiln. I have high alumina and silicon carbide shelves
>and the kiln was flakes off both types of shelves every time. I don't know
>what the issue is. I scrape and sponge the shelves after every firing before
>I use the wash. Any insight into this dilemma would be greatly apriciated.
>
>Thanks
>--James
>
>______________________________________________________________________________
>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.
>
>
>
>
Chuck Wagoner on thu 23 aug 07
25 Calcined Kaolin
25 Kaolin=20
25 Zirocpax
25 Alumina Hydrate
I got it off this list and it is a dream come true! (Thank you to the =
person
that posted it.)
Chuck in Rockville, IN
=20
> I've been using a kiln wash of 50 / 50 EPK and silica. I fire to
> cone 10 in
> a 64 cubic foot gas kiln. I have high alumina and silicon carbide
> shelves
Craig Martell on thu 23 aug 07
James was saying:
>I've been using a kiln wash of 50 / 50 EPK and silica.
Hello James:
If you think about it you are using the same plastics to non-plastics ratio
as a porcelain claybody. The difference is that the claybody non-plastics
are 25 spar and 25 silica. But the effect of plastic shrinkage is the same
with regard to your wash and a porcelain claybody. My point is that you
are applying a wash that's going to shrink to a kiln shelf that doesn't
shrink at all. That's what's causing the flaking. You are using too much
kaolin. It's kinda like putting a raw slip on a bisque pot. You're gonna
have flaking there too.
Your options are to change the wash to one that is lower in kaolin or keep
the same recipe and calcine half the kaolin. Don't forget to figure the
LOI of Kaolin if you do this. It's about 13%.
You can also use a wash with about 25% kaolin and, I would recommend, 75%
alumina oxide. I don't use hydrate because it has a 35% Loss on Ignition
and when you compare the price with alumina oxide you get more alumina for
your hard cash. I got the wash recipe above from Tom Turner. We both use
it with porcelain.
regards, Craig Martell Hopewell, Oregon
Gary Wagoner on sun 26 aug 07
John,
the old 50/50 kaolin&silica kiln wash always flaked badly for me. Now I
use 1 part each kaolin, silica, and alumina hydrate and get much better
results. The alumina hydrate makes it brush on much better and makes it much
less flaky, but it still chips right off with any glaze drips. And it costs
a lot less than $50 a gallon.
Gary
----- Original Message -----
From: "John Post"
To:
Sent: Thursday, August 23, 2007 4:39 PM
Subject: Re: Flaking Kiln Wash
>I use Lee's Amazing Kiln Wash from Axner pottery.
> I fire two kilns 3 times a week as an art teacher and I hate messing
> around with kiln wash.
> With Lee's you scrape the old wash off, brush Lee's on and it stays
> put. No Flaking.
> I only do touch up to my 15 shelves at the beginning of the school year.
> If a glaze blob gets on the shelf I just whack it with a chisel and it
> pops right off.
> This stuff is around $50 bucks a gallon.
> The best part though is that my kiln room floor isn't covered in flakes
> of kiln wash. Neither are my kilns.
> This stuff stays on the shelves.
> It may seem pricey but it makes up for it in all the time you save not
> messing around with flaky wash.
>
> http://www.axner.com/axner/equipment/lees-kiln-wash.php
>
> John Post
> Sterling Heights, Michigan
>
>>I've been using a kiln wash of 50 / 50 EPK and silica. I fire to cone 10
>>in
>>a 64 cubic foot gas kiln. I have high alumina and silicon carbide shelves
>>and the kiln was flakes off both types of shelves every time. I don't know
>>what the issue is. I scrape and sponge the shelves after every firing
>>before
>>I use the wash. Any insight into this dilemma would be greatly apriciated.
>>
>>Thanks
>>--James
>>
>>______________________________________________________________________________
>>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.
>>
>>
>>
>>
>
> ______________________________________________________________________________
> 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.
>
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