Carl Ross on wed 8 feb 12
I've had trouble with pinholes on glazes that I dip and was wondering if =
=3D
there=3D20
are any tips you have... The glazes seem to be the right consistency... t=
=3D
he=3D20
pieces seem to absorb the moisture quickly, It's a stoneware body that I =
=3D
bisque=3D20
fire to ^06. could that be too low? leaving it too porous? Could it be di=
=3D
pped in=3D20
water to slow down the absorption from the glaze? or is bisque firing to =
=3D
a little=3D20
higher cone going to make the difference?=3D20=3D20
I also would like to add CMC to some of the glazes, and am wondering if t=
=3D
here=3D20
is any trick as far as proportions... If I already have glaze mixed, and=
=3D
would=3D20
like to suspend the glaze better, how should I add CMC?? I know it needs=
=3D
to=3D20
be mixed before putting it in the glaze with warm water... Some glazes =
=3D
just=3D20
don't seem to stay suspended like others; need more thorough remixing if =
=3D
I=3D20
leave it any length of time. I'm hoping the CMC will keep it in suspensio=
=3D
n=3D20
better...
Any other hints on glazing would be much appreciated!!
Peace
Carl in Cornville
Carl Ross on wed 8 feb 12
Thanks for the input... it sounds like CMC is the devil...=3D20
the glazes are commercial, dry glazes, so I doubt that needs adjusting. =
=3D
perhaps=3D20
I just need to talk to it nicer...=3D20=3D20
I will try the different watering technique... it is thirsty...
Thanks again,
Carl in Cornville
Liz Gowen 1 on wed 8 feb 12
Carl for the items you have already bisqued squirt them with a water bottle
spay before you dip them You will get the hang of how much water to use whe=
n
it stops the pin holing. Since Ron Roy suggested bisqueing to cone 04 this
pretty much took care of the problem for me. I'll let someone else touch on
the cmc since I use bentonite, not wanting organic decay smell from keeping
my glazes too long and can't remember which additives do this...Liz Gowen
Subject: pinholes, CMC
I've had trouble with pinholes on glazes that I dip and was wondering if
there are any tips you have... The glazes seem to be the right
consistency... the pieces seem to absorb the moisture quickly, It's a
stoneware body that I bisque fire to ^06. could that be too low? leaving it
too porous? Could it be dipped in water to slow down the absorption from th=
e
glaze? or is bisque firing to a little higher cone going to make the
difference?
I also would like to add CMC to some of the glazes, and am wondering if
there is any trick as far as proportions... If I already have glaze mixed,
and would like to suspend the glaze better, how should I add CMC?? I know
it needs to
be mixed before putting it in the glaze with warm water... Some glazes
just
don't seem to stay suspended like others; need more thorough remixing if I
leave it any length of time. I'm hoping the CMC will keep it in suspension
better...
Any other hints on glazing would be much appreciated!!
Peace
Carl in Cornville
Gayle Bair on wed 8 feb 12
The spraying is a great idea!
When I was having trouble with pinholes on my production soap dishes which
had textures that a thicker glaze just couldn't coat. So I watered down the
glaze and dipped the pieces in it. After decorating, I dip in the regular
glaze which I use thinner than most potters.
I also used Ron Roy's suggestion of firing to ^04 (Thanks Ron).
Gayle Bair
www.claybair.com
On Wednesday, February 8, 2012, Liz Gowen 1 wrote:
>
Carl for the items you have already bisqued squirt them with a water bottle
> spay before you dip them You will get the hang of how much water to use
when
> it stops the pin holing. Since Ron Roy suggested bisqueing to cone 04 thi=
s
> pretty much took care of the problem for me. I'll let someone else touch
on
> the cmc since I use bentonite, not wanting organic decay smell from
keeping
> my glazes too long and can't remember which additives do this...Liz Gowen
>
> Subject: pinholes, CMC
>
> I've had trouble with pinholes on glazes that I dip and was wondering if
> there are any tips you have... The glazes seem to be the right
> consistency... the pieces seem to absorb the moisture quickly, It's a
> stoneware body that I bisque fire to ^06. could that be too low? leaving
it
> too porous? Could it be dipped in water to slow down the absorption from
the
> glaze? or is bisque firing to a little higher cone going to make the
> difference?
>
> I also would like to add CMC to some of the glazes, and am wondering if
> there is any trick as far as proportions... If I already have glaze
mixed,
> and would like to suspend the glaze better, how should I add CMC?? I kno=
w
> it needs to
> be mixed before putting it in the glaze with warm water... Some glazes
> just
> don't seem to stay suspended like others; need more thorough remixing if =
I
> leave it any length of time. I'm hoping the CMC will keep it in suspensio=
n
> better...
>
> Any other hints on glazing would be much appreciated!!
>
> Peace
>
> Carl in Cornville
>
--
Gayle
Gayle Bair Pottery
gayle@claybair.com
www.claybair.com
Barbara Francis on wed 8 feb 12
I have had a great deal of pinholing problems and the problem was pin point=
=3D
ed to the clay I was using.=3DA0 I used Cinco Blanco from Armadillo Clay in=
A=3D
ustin.=3DA0 I had 2 loads of pots that pinholed badly.=3DA0 I am now trying=
the=3D
Laguan b=3D3Dmix and also a cone 6 stoneware from Trinity Ceramics.=3DA0 I=
hav=3D
e had no Pin Holes.=3DA0 I have tried a new batch of the Cinco Blanco that =
wa=3D
s mixed in January of 2012.=3DA0 It pinholed all over the place, on all gla=
ze=3D
s.=3DA0 They think is may be an issue of the sulfer content in the clay.=3D=
A0 H=3D
ope this helps.=3DA0 Barb Francis=3D0A=3D0A=3D0A=3D0A______________________=
__________=3D
=3D0AFrom: Gayle Bair =3D0ATo: Clayart@LSV.CERAMICS.ORG=
=3D0A=3D
Sent: Wednesday, February 8, 2012 11:05 AM=3D0ASubject: Re: pinholes, CMC=
=3D0A=3D
=3D0AThe spraying is a great idea!=3D0A=3D0AWhen I was having trouble with =
pinhol=3D
es on my production soap dishes which=3D0Ahad textures that a thicker glaze=
j=3D
ust couldn't coat. So I watered down the=3D0Aglaze and dipped the pieces in=
i=3D
t. After decorating, I dip in the regular=3D0Aglaze which I use thinner tha=
n =3D
most potters.=3D0A=3D0AI also used Ron Roy's suggestion of firing to ^04 (T=
hank=3D
s Ron).=3D0A=3D0AGayle Bair=3D0Awww.claybair.com=3D0A=3D0AOn Wednesday, Feb=
ruary 8, 2=3D
012, Liz Gowen 1 wrote:=3D0A>=3D0ACarl for the items =
you =3D
have already bisqued squirt them with a water bottle=3D0A> spay before you =
di=3D
p them You will get the hang of how much water to use=3D0Awhen=3D0A> it sto=
ps t=3D
he pin holing. Since Ron Roy suggested bisqueing to cone 04 this=3D0A> pret=
ty=3D
much took care of the problem for me. I'll let someone else touch=3D0Aon=
=3D0A>=3D
the cmc since I use bentonite, not wanting organic decay smell from=3D0Ake=
ep=3D
ing=3D0A> my glazes too long and can't remember which additives do this...L=
iz=3D
Gowen=3D0A>=3D0A> Subject: pinholes, CMC=3D0A>=3D0A> I've had trouble with=
pinhole=3D
s on glazes that I dip and was wondering if=3D0A> there are any tips you ha=
ve=3D
... The glazes seem to be the right=3D0A> consistency... the pieces seem to=
a=3D
bsorb the moisture quickly, It's a=3D0A> stoneware body that I bisque fire =
to=3D
^06. could that be too low? leaving=3D0Ait=3D0A> too porous? Could it be d=
ippe=3D
d in water to slow down the absorption from=3D0Athe=3D0A> glaze? or is bisq=
ue f=3D
iring to a little higher cone going to make the=3D0A> difference?=3D0A>=3D0=
A> I a=3D
lso would like to add CMC to some of the glazes, and am wondering if=3D0A> =
th=3D
ere is any trick as far as proportions...=3DA0 If I already have glaze=3D0A=
mixe=3D
d,=3D0A> and would like to suspend the glaze better, how should I add CMC??=
=3D
=3DA0 I know=3D0A> it needs to=3D0A> be mixed before putting it in the glaz=
e with=3D
warm water...=3DA0 Some glazes=3D0A> just=3D0A> don't seem to stay suspend=
ed lik=3D
e others; need more thorough remixing if I=3D0A> leave it any length of tim=
e.=3D
I'm hoping the CMC will keep it in suspension=3D0A> better...=3D0A>=3D0A> =
Any ot=3D
her hints on glazing would be much appreciated!!=3D0A>=3D0A> Peace=3D0A>=3D=
0A> Carl=3D
in Cornville=3D0A>=3D0A=3D0A--=3D0AGayle=3D0A=3D0AGayle Bair Pottery=3D0Ag=
ayle@claybair.=3D
com=3D0Awww.claybair.com
ronroy@CA.INTER.NET on wed 8 feb 12
Hi Carl,
Bisqueing higher can help to get rid of orgainics in a clay body -
having lots of fresh oxygen in a bisque firing is also helpful - try
leaving a top spy open - however - sometimes its the glaze itself.
If it's happening to all your glazes then it may well be the bisque
but if it only happens to some glazes then maybe an adjustment to
those glazes may be the answer.
The new supplies of custer have changed - more refractory - so that
may be the cause if it started happening when you got a new supply of
Custer.
I can reformulate glazes to stop the pin holing.
RR
Quoting Carl Ross :
> I've had trouble with pinholes on glazes that I dip and was
> wondering if there
> are any tips you have... The glazes seem to be the right consistency... t=
he
> pieces seem to absorb the moisture quickly, It's a stoneware body
> that I bisque
> fire to ^06. could that be too low? leaving it too porous? Could it
> be dipped in
> water to slow down the absorption from the glaze? or is bisque
> firing to a little
> higher cone going to make the difference?
>
> I also would like to add CMC to some of the glazes, and am wondering if t=
here
> is any trick as far as proportions... If I already have glaze
> mixed, and would
> like to suspend the glaze better, how should I add CMC?? I know it needs=
to
> be mixed before putting it in the glaze with warm water... Some glazes =
just
> don't seem to stay suspended like others; need more thorough remixing if =
I
> leave it any length of time. I'm hoping the CMC will keep it in suspensio=
n
> better...
>
> Any other hints on glazing would be much appreciated!!
>
> Peace
>
> Carl in Cornville
>
Steve Mills on wed 8 feb 12
A few questions.=3D20
Is this a new problem with glazes you have fired successfully before, or ha=
v=3D
e they always pinholed?
Are you using cones, mini-cones in a kiln sitter, or a programme controller=
w=3D
ith a thermocouple to gauge finish temperature?
The problem with CMC is it is an organic compound from the food industry, s=
o=3D
unless you add it together with an antiseptic (not just any antiseptic but=
a=3D
n industrial one) to counteract degradation, it can go "off", smell foul, a=
n=3D
d separate from the glaze material quite quickly.=3D20
Better to suspend your glaze with a small percentage of Bentonite, or a des=
s=3D
ert spoon per gallon of a saturated solution of Calcium Chloride. Don't use=
t=3D
he latter if your glaze contains Bone Ash.=3D20
I use either to very good effect with my non-clay containing glazes.=3D20
Steve M
Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my iPod
On 8 Feb 2012, at 08:47, Carl Ross wrote:
> I've had trouble with pinholes on glazes that I dip and was wondering if =
t=3D
here=3D20
> are any tips you have... The glazes seem to be the right consistency... t=
h=3D
e=3D20
> pieces seem to absorb the moisture quickly, It's a stoneware body that I =
b=3D
isque=3D20
> fire to ^06. could that be too low? leaving it too porous? Could it be di=
p=3D
ped in=3D20
> water to slow down the absorption from the glaze? or is bisque firing to =
a=3D
little=3D20
> higher cone going to make the difference? =3D20
>=3D20
> I also would like to add CMC to some of the glazes, and am wondering if t=
h=3D
ere=3D20
> is any trick as far as proportions... If I already have glaze mixed, and=
w=3D
ould=3D20
> like to suspend the glaze better, how should I add CMC?? I know it needs=
t=3D
o=3D20
> be mixed before putting it in the glaze with warm water... Some glazes =
j=3D
ust=3D20
> don't seem to stay suspended like others; need more thorough remixing if =
I=3D
=3D20
> leave it any length of time. I'm hoping the CMC will keep it in suspensio=
n=3D
=3D20
> better...
>=3D20
> Any other hints on glazing would be much appreciated!!
>=3D20
> Peace
>=3D20
> Carl in Cornville
Lee on wed 8 feb 12
On Wed, Feb 8, 2012 at 2:47 AM, Carl Ross wrote:
> I've had trouble with pinholes on glazes that I dip and was wondering if =
=3D
there
> are any tips you have... The glazes seem to be the right consistency... t=
=3D
he
> pieces seem to absorb the moisture quickly, It's a stoneware body that I =
=3D
bisque
> fire to ^06. could that be too low? leaving it too porous? Could it be di=
=3D
pped in
> water to slow down the absorption from the glaze? or is bisque firing to =
=3D
a little
> higher cone going to make the difference?
Carl, I bisque to cone 012. My teacher bisqued lower: to dull red
heat and lower.
Better than spraying or dipping, use a wet sponge to wipe the
surface of the form, inside and out.
During my apprentice, when we glazed, I was the bisque
sponger. Some of the noborigama bisqued work was so soft, you'd
have to be careful you didn't break them when you sponged. The first
time I wiped noborigama bisqued teabowls, I broke two. My teachers
teabowls went for $6,000,00 and up when they were completed.
--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/
=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Lee on thu 9 feb 12
On Thu, Feb 9, 2012 at 3:24 PM, Carl Ross wrote:
> yeah, that's probably more accurate...
>
> little bubbles when the glaze is applied... I'm a little light on the lin=
=3D
go
>
> the glaze is more matte glaze
>
So it ain't organics. Try sponging with water.
Also, when you see pinholes after glazing, you can rub them out with your
finger.
--
Lee Love in Minneapolis
http://mingeisota.blogspot.com/
"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D97tha=
t is, "T=3D
he land
of eternal youth is behind the house, a beautiful land fluent within
itself." -- John O'Donohue
Carl Ross on thu 9 feb 12
Ron, you said to perhaps open the top peephole... I do use a downdraft ve=
=3D
nt=3D20
which I would think do the same thing... your thoughts?
Bonnie Staffel on thu 9 feb 12
What I don't understand is why potters are using food grade CMC when =3D
there
is a ceramic grade which in my own instance, has never set up mold in my
glazes or when mixed with water and stored. I would get on my =3D
distributor or
dealer to make sure that they have ceramic grade. I have been using this
material for years with no mold or other degradation problems. It takes =3D
so
little to be added to one's glaze a pound lasts for a long time. My
measurement is 1/4 of 1% addition. Keeps the glaze suspended for many =3D
dips
before having to give the glaze a stir.
There is another product available I think from Axner's that is called
Flocs. This keeps the glaze from becoming a nard mass at the bottom and =3D
is
easily kept stirred even after sitting for months. Only a few drops are
needed of this material as well.=3D20
I have written about these materials in this forum as well as others for
years. I have been a potter for over 60 years and still have so much to
learn. But in those years I did learn a few things that I have passed on =
=3D
to
others. That is part of the "payback" system I believe in. I also learn =3D
a
lot from all of you as well, which is what makes working in clay so
fascinating.=3D20
As for pinholes, wetting the bisque just before dipping or spraying =3D
covers
many problems with this action. There are probably other reasons for the
pinholes, still washing is a must IMO.
Regards,
Bonnie
http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
DVD Throwing with Coils and Slabs
DVD Introduction to Wheel Work
Charter Member Potters Council
Lee on thu 9 feb 12
Veegum don't stink. See below.
When do your pinholes first appear? If you see them
immediately after glazing, it is air coming up from the bisque.
Sponging with water will stop it.
TCMC (Carboxy Methyl Cellulose) is more similar to the
gelatin, it sets up a very firm gel in water. Then when that gelatin/water
material is dispersed in a glaze mix it disperses as a lot of individual je=
=3D
lly
particles or non scientific term globs. The globs are can be seen if the gl=
=3D
aze
is pressed between two plates of glass. So the gelatin particles are relati=
=3D
vely
large by microscopic standards. CMC both reduces settling physically in the
bucket and hold glaze ingredients together when drying. In the glaze on the=
=3D
pot
CMC acts as a kind of binder with glaze particles and binds to the pot as w=
=3D
ell.
This binding or sticking mostly takes place below the surface of the glaze
coating sticking glaze ingredients together more in a macro
microscopic fashion.
CMC will break down from bacteria action over time. If you use it could use=
=3D
an
inhibitor, use it up in a relatively short time, or replenish it if its eff=
=3D
ect
diminishes.
Veegum (a colloidal Magnesium Aluminum Silicate) is all mineral based and a=
=3D
cts
more like a clay. In water Veegum is colloidal so it thickens the water jus=
=3D
t
like CMC does but, in a somewhat looser, weaker, smaller fashion. Its bindi=
=3D
ng
power is at the molecular level or very microscopic and not as easily obser=
=3D
ved
in glaze. Veegum colloids make water appear as if it were thickened like CM=
=3D
C,
but still more flowable or movable. So it will take much more Veegum than C=
=3D
MC
if it is being used for dispersing in the glaze bucket and more if it is be=
=3D
ing
used as a binder to hold the glaze on the pot. Veegums have a tendency to f=
=3D
orm
films and in glazes form the film on the surface of the glaze when it
dries, not
within like CMC. Veegum is generally much weaker so if it is doing the same=
=3D
job
as CMC it requires much more to obtain a similar dispersing effect or bindi=
=3D
ng
effect.
--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/
=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Carl Ross on thu 9 feb 12
wow... you sure know something about it... a lot to take in!!
On Thu, Feb 9, 2012 at 8:17 AM, Lee wrote:
> Veegum don't stink. See below.
>
> When do your pinholes first appear? If you see them
> immediately after glazing, it is air coming up from the bisque.
> Sponging with water will stop it.
>
>
> TCMC (Carboxy Methyl Cellulose) is more similar to the
> gelatin, it sets up a very firm gel in water. Then when that gelatin/wate=
=3D
r
> material is dispersed in a glaze mix it disperses as a lot of individual
> jelly
> particles or non scientific term globs. The globs are can be seen if the
> glaze
> is pressed between two plates of glass. So the gelatin particles are
> relatively
> large by microscopic standards. CMC both reduces settling physically in t=
=3D
he
> bucket and hold glaze ingredients together when drying. In the glaze on
> the pot
> CMC acts as a kind of binder with glaze particles and binds to the pot as
> well.
> This binding or sticking mostly takes place below the surface of the glaz=
=3D
e
> coating sticking glaze ingredients together more in a macro
> microscopic fashion.
> CMC will break down from bacteria action over time. If you use it could
> use an
> inhibitor, use it up in a relatively short time, or replenish it if its
> effect
> diminishes.
>
> Veegum (a colloidal Magnesium Aluminum Silicate) is all mineral based and
> acts
> more like a clay. In water Veegum is colloidal so it thickens the water
> just
> like CMC does but, in a somewhat looser, weaker, smaller fashion. Its
> binding
> power is at the molecular level or very microscopic and not as easily
> observed
> in glaze. Veegum colloids make water appear as if it were thickened like
> CMC,
> but still more flowable or movable. So it will take much more Veegum than
> CMC
> if it is being used for dispersing in the glaze bucket and more if it is
> being
> used as a binder to hold the glaze on the pot. Veegums have a tendency to
> form
> films and in glazes form the film on the surface of the glaze when it
> dries, not
> within like CMC. Veegum is generally much weaker so if it is doing the
> same job
> as CMC it requires much more to obtain a similar dispersing effect or
> binding
> effect.
> --
> Lee Love in Minneapolis
> http://mingeisota.blogspot.com/
>
> "Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D97t=
hat is, =3D
"The
> land of eternal youth is behind the house, a beautiful land fluent
> within itself." -- John O'Donohue
>
John Britt on thu 9 feb 12
Carl,
I don't think you have pinholes. They come after firing.=3D20
Sounds like you have bubbles when applying the glazes.
That may or may not be a problem. If it is on shinos it is good. On matt =
=3D
glazes it=3D20
may be bad and lead to pinholes. On a glossy glazes it may not matter as =
=3D
they=3D20
heal over in the firing.
If you dip one coat and let it dry - that second coat will most always ha=
=3D
ve=3D20
bubbles in the coat. Try to either dip the bisque in water and let dry a =
=3D
bit before=3D20
you glazing. Or dip one coat and let it "stiffen" but NOT dry and dip aga=
=3D
in. You=3D20
should get no bubbles in the second dip.
john britt pottery
Carl Ross on thu 9 feb 12
yeah, that's probably more accurate...
little bubbles when the glaze is applied... I'm a little light on the lingo
the glaze is more matte glaze
On Thu, Feb 9, 2012 at 12:53 PM, John Britt wro=
te:
> Carl,
>
> I don't think you have pinholes. They come after firing.
>
> Sounds like you have bubbles when applying the glazes.
>
> That may or may not be a problem. If it is on shinos it is good. On matt
> glazes it
> may be bad and lead to pinholes. On a glossy glazes it may not matter as
> they
> heal over in the firing.
>
> If you dip one coat and let it dry - that second coat will most always ha=
ve
> bubbles in the coat. Try to either dip the bisque in water and let dry a
> bit before
> you glazing. Or dip one coat and let it "stiffen" but NOT dry and dip
> again. You
> should get no bubbles in the second dip.
>
> john britt pottery
>
>
ronroy@CA.INTER.NET on thu 9 feb 12
Hi Carl,
Yes - I should have included that - if you have a vent running (with
no holes in the flexible tubing) there will usually be enough oxygen
to help burn up any organics in the clay - there are some clays that
have different amounts of carbon in them depending on when and where
mined so even if your clay is OK this time - it does not mean it will
be OK next time.
By the way - if the glaze makers are using Custer - and they are not
aware of the changes in that material - that can result in pin holing.
Custer is now short 3% potassium oxide - K2O - a flux that promotes
running - in other words a low viscosity flux. One of the cures for
pin holing is to increase such low viscosity oxides including Na2O and
Li2O and K2O. Increasing the flow in glazes helps to heal over pin
holes.
Because of the way Pacer has handled this problem they may not have
informed the glaze and clay making companies that the current Custer
is sub par.
I'm surprised that no supplier has commented on this - do they know
what is going on? Has Pacer warned anyone? Are all the clays and
glazes produced with Custer now not meting as much?
Quoting Carl Ross :
> Ron, you said to perhaps open the top peephole... I do use a downdraft ve=
nt
> which I would think do the same thing... your thoughts?
>
John Britt on fri 10 feb 12
Carl,
It is not that I am a nitpicker on terminology but it makes a difference =
=3D
for a=3D20
solution. One is firing, venting, glaze composition and the other is appl=
=3D
ication.=3D20=3D20
Work on the application solutions I suggested and let me know if you need=
=3D
more,
john britt pottery
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