Barbara Mueller on mon 2 sep 02
That=92s an amazing post Lily I will put in my files for a later time =
and
use part of it now. Being a newbie I would like to tell another version
of the story.=20
Bought the Cone 6 book and began doing test tiles using the High Calcium
Semimatt glaze # 2. Came up with a series of glazes using colorants
called them Barb's Morris Green (variegated slate blue), Khaki by
Crackie (raw sienna), Coffee Latt=E9 Please and Soyuz Green (hey have =
you
every seen the name on paint chips it=92s a job I have always wanted!).
They worked together in a really sweet way and I had mixed them. I
liked that. After the test tiles I began to mix up 2000 mg of each one
not bothering to take a globe view of how much of each chemical I had on
hand. My initial purchase was rather smallish.
When I began to run out of chemicals and colorants I would make a slip
of paper and put it into the bucket of what was missing. The chemicals
and oxides came a few days later and I pulled out the papers and thought
that I had them in the correct order and began to add what was missing
to each batch. I did notice the rutile was a lot darker but didn't
think anything about that. =20
When I did my next glaze firing I was shock that the inside of my jar
which should have been Khaki was a beautiful, beautiful blue with a
touch of dark dark blue. I thought I had probably used the wrong bucket
or something because I had also pulled out the Laguna Royal Blue that I
used to use but this color was nicer looked a little more liquid. Then
I saw the Barb's Morris Green and it did not look like the color of my
Morris rather it was more bluish green. Now both of these colors are
wonderful. Sadly maybe even more wonderful then the original colors
that I had mixed but they are a unknown formula now because I don't know
if I mixed them wrong, or it was the Rutile or what. I am tempted to
hoard these glazes for something really special and remix which is
probably what I will do.
I know that this happens for I have heard about this before. Wished
that it could have happened after I was a little more experienced. In
the meantime Lily I will put a truckload of plastic bags in my studio
and measure in them first and then mix everything together. Thanks for
the tip.
B
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG] On
Behalf Of Lily Krakowski
Sent: Monday, September 02, 2002 9:53 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: glaze rescue
WHAT YOU NEED FIRST is some strong coffee or some strong ice tea.
Then, as my mother would have suggested, wash your face with a nice
cold
washcloth. And take it from there.
When you say first batch and second batch that suggests a MIXING error.
Sounds like you put in a lot more of something--maybe rutile --than you
should have. Or left something out entirely.
ALSO POSSIBLE that you did not sieve the whole 5000 gram batch--I find
stirring has limited success and always sieve--(see below) and something
vital stayed at the bottom.
Sieve the entire batch. Sieve it twice if you have any doubts.
Remove a quart or so, and DRY IT THOROUGHLY. An old roasting pan from
the
thrift shop, lined with a piece of sort cloth (elderly roasting tins
often
have rust spots--is a good wide surface for drying. Or you can use large
pan
sugggested below.
Now weigh out small amounts of the dry stuff. Mix one up plain with
water
and see if that does it--i.e., you did not mix well.
If you want wait till you have tested that test tile, before you "do"the
others.
Now--this is the more annoying part. You have six basic ingredients.
Weigh
out NEW glaze OMITTING ONE INGREDIENT ENTIRELY. Your first batch would
omit
the feldspar, the second batch omit the frit etc. You then mix the new
batches with what you have weighed out of the old. Each of these mixes
would have 1/2 of one original ingredient. Where you left out the
feldspar
you would have 1/2 the feldspar and so on. Testing these will give you
a
clue as to what you left out, or put too much of in.
since these tests will not have colorant added you also will learn
whether
you overdid colorant.
Truth to tell this is a bit boring, although I have had to do it many
times.
However. Next time you commit yourself to 5 K of any glaze be a dear
and
weigh out each ingredient, put it in a plastic bag (1 gallon food
storage
ones) and reweigh before dumping in bucket of water. As I need to weigh
out
big quantities in batches, I use smaller bags--actually saved vegetable
bags
from the supermarket--and then reweigh each. I.E. I will weigh out 3
five
hundred gram bags and one 350 gram bag of Whatever and reweigh before I
combine.
Let us know....
BELOW; for this kind of screening, make yourself a big sieve. Build a
box
like frame out of 3x1 board, cover the bottom with silkscree fabric--I
use
the kind they sell for glitter. Stretch the fabric tightly epoxy it on.
For a big box put a thin crosspiece of lath across the middle. I
suggest
you shellac or polyurethane the wood beforfe adding the screen. Use
such a
screen over a kitty litter pan--a new one, or Kitty will get mad--or a
plastic baby bath--something with a bigger opening than a dishpan or a 5
gallon pail
k.m.whipple@ATT.NET writes:
> I'm hoping someone can walk me thru the steps of trying
> to salvage a bucket of glaze--at this stage in my clay
> life, i can't afford to ditch such a quant00ity of
> materials.
> The glaze is Ron and John's Bright Sky Blue, and for
> clarity, here is the recipe:
>
> G-200 Feldspar 20 (i subbed custer)
> Frit 3134 20
> Wollastonite 10
> EPK 20
> talc 11.5
> Silica 18.5
> Cobalt carb 1%
> Rutile 6%
> RIO .5%
>
> My notes from the mixing are no help, i crossed my I's
> and dotted my t's meticulously. The first batch came
> out fully melted, but not the right color--more
> greygreen than blue, tho it did go smoky/baby blue
> where overlapped with white. I found some discussion on
> R & J's site that suggested this might have happened
> because i cooled the kiln too slowly for that glaze, so
> on the second go round, i didn't fire down, just let
> the sitter turn the kiln off. This second round is
> probably the ugliest thing i've ever seen: incredible
> crawling and a truly yucky, pasty olive patched with
> splotches of insipid powder blue where it was thicker--
> which is where it crawled worst, of course---ick.
> So:
> *is custer so different that G-200? my notes/research
> say they are both potassium spars and can be
> substituted.
> *i diagnose that i must have left out some flux
> (that crawly underfired look...); does that sound right?
> *but might my rutile also be at fault for the color
> problems? (my tests for Spearmint glaze also turned out
> goose-poop ugly)
>
> I have nearly all of a 5000 gm batch of this glaze left.
> How does one begin trying to fix such a thing: i am
> thinking i will have to measure out the liquid volume,
> break it down into something i can work with, like cups
> and quarts, and make some tests, a teaspoon more of
> silica or spar or frit per 1/2 cup...if i get some
> tiles that look good, extrapolate the quantities back
> into the bucketful.
>
> Any and all help will be greatly appreciated--
>
> Kathy
> Brooker, Fl
>
>
________________________________________________________________________
______
> 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.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
________________________________________________________________________
______
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.
| |
|
