Lois Sharpe on tue 25 may 10
another question about glaze overlapping
I found an overlapping combination I really like, but,
it was pinholing....
I upped my bisque, fired hotter, soaked the kiln longer, fired down.
everything I could think of to remove the offending pinholes.=3D20
Still had pinholes! smaller, but still there!
Then I discovered NO pin holes when I dip the pot to apply both glazes.=3D2=
0=3D
I normally brush these on, because, my outside glaze is different, than =3D
my interior glaze,
and I cannot dip. Pouring shows overlap lines, but brushing gives a =3D
thick/thin mottling all over that works for me.
(and I have gotten very fast at it!) I brush on many different glazes =3D
for each firing. And have for a long time.
none have ever done this.
Both glazes pinhole with brushing, one worse than the other.
neither pinhole when dipped.
SO, why can brushing a glaze cause pinholes?
cheers
lois
Lois Sharpe
Durham NC=3D20
Karen Gringhuis on tue 25 may 10
Jeff -
"WHY" overlapping glazes yields a different result than mixing two glazes
together? Of this I am not certain except that it does. Mixing together
seems to blur glaze textures v. overlapping which seems to promote more
texture in the glazed surface - when I compared this w/ two colors in the
same base. A friend mixes wet batches of two separate glazes, then dumps
them together bc this gives diff. results than combining the formulas into
one mix. Go figure.
First (and only?) rule - maximize what you already have. Make sample cups,
assuming they are typical of your vertical work surfaces, of med. size
holding approx. 6 oz. of water i.e. NOT petite. (If you make tiles, use fla=
t
tiles.) Texture half the cup vertically as usual. Using all the glazes you
ALREADY have, do over-under, under-over of all possible combinations but
only one combination per cup so you can really see the results. Important -=
-
do NOT cover the entire cup w/ the top glaze. Only cover about the top 2/3=
.
You want to see the EDGE where the top glaze stops against the underneath
glaze.
Fire these all together, observe and take serious notes, labeling each cup.
My most dramatic results occured where the edge of a top GLOSSY glaze
stopped when put over a matt glaze. Truthfully I never tried it the other
way around using matt over glossy. Glossy on top of matt is a rough "rule
of thumb" but your test cups & your personal taste will tell you to follow
or ignore this. The top glossy glaze may "move" melting downward and where
its run stops should have some interesting action incl. color change.
I'm not sure what you mean by "slip glaze" or how you are getting your
texture. But if you are texturing at all deeply into your surface, try
covering the surface first w/ a colored slip, then texture thru it so the
orig. clay body shows. See what that looks like under your transparent
glazes. Actually test it under all of your glazes.
For different unexpected textures, take 8 oz. liquid (within my experience
this is ROUGHLY comparable to a 100 gram dry test batch) of a transparent
glaze you already have & throw in some titanium or lithium. W/ one 8 oz.
jar, you can successively test 4%, 6%,10% just by adding the oxide and
making a test; then add more oxide & make another test etc. These oxides
are texturizers and may give you some interesting results.
For a wild and crazy flambeau look, put some black slip (colored w/ Mn, Co,
Cr, Fe) under a fake ash glaze. Inlay a line of slip into leather-hard ware
or dot it on - a sm. amt. of slip will go a ways.
Hope this helps. More qns, feel free to write off list.
Karen Gringhuis
On Sun, May 23, 2010 at 2:42 PM, Jeff Jeff wrote:
> I'm getting back into glaze experimentation and just wondering if anyone
> knows why overlapping glazes yields a different result than mixing two
> glazes
> together?
>
> As well are there general rules regarding overlapping: i.e. fluid glazes
> best under or slip glazes best over, kind of a thing? I have a limited
> budget
> and can't go wild but would like to explore more than before.
>
> I used to think my textures look best under solid opaque glazes. I've
since
> realized that fluid, transparent glazes accentuate the textures in
> unexpected, and more pleasant, ways.
>
> Thanks
>
> Jeff Longtin
> Minneapolis
Gay Judson on tue 25 may 10
Oh no. Do NOT reply off list. This is a great discussion and I want
to be in on it! Please...
Gay Judson in San Antonio
On May 25, 2010, at 10:25 AM, Karen Gringhuis wrote:
> Jeff -
>
> "WHY" overlapping glazes yields a different result than mixing two
> glazes
> together? Of this I am not certain except that it does. ....
> Hope this helps. More qns, feel free to write off list.
>
> Karen Gringhuis
>
>
>
> On Sun, May 23, 2010 at 2:42 PM, Jeff Jeff wrote:
>
>> I'm getting back into glaze experimentation and just wondering if
>> anyone
>> knows why overlapping glazes yields a different result than mixing
>> two
>> glazes
>> together?
Jeff Jeff on tue 25 may 10
Thanks for all the great responses. I knew that testing is really the best
way to go but with limited funds I thought I'd see if some simple rules
still apply.
SOME overlap results are on my etsy page: www (dot) jefflongtin (dot) etsy
(dot) com
Take care
Jeff Longtin
Minneapolis
Snail Scott on wed 26 may 10
On May 25, 2010, at 9:49 PM, Lois Sharpe wrote:
>
> SO, why can brushing a glaze cause pinholes?
I think (for no substantiated reason at all) that
when dipping, the glaze is drawn deep into the
pores of the clay by the water that gets absorbed,
while brushing tends to create a layer that sits on
top of the clay and has less opportunity to penetrate.
It's those unfilled pores that become the starting
point for some pinholing.
Obviously, this is only one possible factor, since
pinholing can come from many causes, but it is
my best theory on why glazes that behave well
when dipped sometimes give pinhole trouble when
brushed on.
Though it's not a frequent problem for me, I often
moisten the bisque quite a lot before brushing, in
the belief that this helps wick the glaze down into
the clay. It seems to help, but my own observations
are based on too few variations to be definitive.
In any case, the first layer of brushed glaze is the
most difficult to get applied evenly, and damper
bisque allows for smoother, better behaved brush
strokes and for freer, more gestural painted designs
as well. Since it's no bas idea to wipe down bisque
before glazing anyway, it's scarcely even an extra
step to get it wet enough to make a difference in
brushing - both in application behavior and in
results.
-Snail
>
>
>
>
> cheers
> lois
>
>
>
>
>
>
> Lois Sharpe
> Durham NC
paul gerhold on wed 26 may 10
Lois,
Good question. I have noticed the same thing and have attributed the effec=
t
to the fact that when you brush you are pulling the glaze across the surfac=
e
of the clay rather than pulling the glaze into the clay from absorbing the
water. Two things that have helped me are:
1) Mix the glaze with more water and use multiple coats.
2) In extreme cases try prewetting the pot before glazing.
Paul
Lee Love on wed 26 may 10
If you sponge your bisque before you brush, you can eliminate
pinholing from air in the bisque.
--=3D20
--
Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
C Sullivan on wed 26 may 10
Mornin' Lois
On brushing and pinholes: generally i dampen the pot before glazing; then
after brushing on the first glaze and after it has dried a wee bit, using m=
y
thumb, i smooth all the glaze all over the pot with firm but not intense
pressure.
After applying the second glaze over this, i repeat the process of smoothin=
g
it.
Seems to work like a charm. No pinholes.
Hope this helps
Chae
On Tue, May 25, 2010 at 8:49 PM, Lois Sharpe wrote:
> another question about glaze overlapping
>
> I found an overlapping combination I really like, but,
> it was pinholing....
>
> I upped my bisque, fired hotter, soaked the kiln longer, fired down.
> everything I could think of to remove the offending pinholes.
> Still had pinholes! smaller, but still there!
>
> Then I discovered NO pin holes when I dip the pot to apply both glazes.
> I normally brush these on, because, my outside glaze is different, than m=
y
> interior glaze,
> and I cannot dip. Pouring shows overlap lines, but brushing gives a
> thick/thin mottling all over that works for me.
> (and I have gotten very fast at it!) I brush on many different glazes for
> each firing. And have for a long time.
> none have ever done this.
>
>
> Both glazes pinhole with brushing, one worse than the other.
> neither pinhole when dipped.
>
> SO, why can brushing a glaze cause pinholes?
>
>
>
> cheers
> lois
>
>
>
>
>
>
> Lois Sharpe
> Durham NC
>
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