Edouard Bastarache Inc. on sat 1 jul 06
How to preserve glazes containing high boron frits.
By Smart.Conseil :
http://perso.orange.fr/smart2000/borate_de_calcium.htm
http://perso.orange.fr/smart2000/borate_de_calcium.htm#english
Edouard Bastarache
Le Fran=E7ais Volant
The Flying Frenchman
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/potier/
http://www.ceramicanorio.com/exposicoesetc/exposi=E7oesetc.html
Alisa Liskin Clausen on thu 6 jul 06
Dear Edouard
This is an excellent article and perhaps explains some of the frustration
I have had with premixed Raku glazes.
Although Raku glazes are easy enough to mix, if you call one Frit in water
a glaze recipe!, but still, there are times when myself and students use
premixed Raku glazes from our supplier.
The premixed glazes, from jar to jar, sometimes are fine and sometimes
bubble. Although,we at first thought the bad onesneeded more time to
smooth out, they only went from bubbling to just over fired, but never
smoothed out.
I am thinking that this study by Smart, suggesting that the high boron
frit's causes crystals in the glazes and subsequently bubbles on the
surface when the water is released, is our problem. The premixed glazes
sit on the dealer's shelf for a long time and perhaps are developing this
cyrstal problem. We do not seive the premixed glazes, but now we will.
In general, I mix my own Raku glazes with amounts just for each firing
because I fire infrequenetly or a rash of firings within weeks, and then
not again for several months.
I will advise my students to try using demineralized water instead of tap
water if they intend to mix Raku glazes that they will store. They also
should seive the premixed ones.
Thanks for helping to solve this mystery with good explanation.
The other mystery perhaps Smart has an idea about, is why the premixed
yellow Raku glaze needs much longer to mature than all of the other
glazes. Since I do not know what makes the yellow, I assume it is a stain.
However, I wonder if stains can make a Raku glaze any more refractory than
without. The whites with refractory opacifiers melt as quickly (20
minutes at 900c)as the clear mostly Boron Frit glaze.
Best regards from Alisa in Denmark
(cheating, still in NJ)
Edouard Bastarache Inc. on thu 6 jul 06
Alisa,
thank you for your kind words
I will forward your comments to Smart.Conseil.
Later,
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/potier/172943983/
http://www.flickr.com/photos/potier/172941969/
Alisa Liskin Clausen on fri 7 jul 06
>Alisa,
>
>Smart says he has no idea about your yellow glaze,
>probably due to the fact he does not have the
>formula.
>
Not a surprise either, as I have no idea myself. Pesky problem with
premixed glazes off the shelf. I only assume it is 90 Frit, 10 Kaolin and
a stain. Only because this is the base the supplier recommends, but their
own mixture could be a highly guarded secret.
I am pleased however, feeling rather smug actually, that M. Smart has
given me a good piece of information pertinent to a problem that has
puzzled me, which I can take home and discuss with my colleagues. It will
be interesting to see if sieving the glazes helps smooth it out in the
firings.
I had been looking for cyrstals on the surface of my glaze buckets that
get quite cold in the winter, to see if I could capture them and fire them
on the surface of my dipped pots (John Britt). Nothing last winter so
will have to try it again this winter. But first must remember to enjoy
this brief warm season.
Perhaps people who Raku a lot have opinions on this theory to share here?
Best regards, Alisa in Denmark
Edouard Bastarache Inc. on sat 8 jul 06
Alisa,
I have an idea, "a pipe-smoker's hypothesis" :
let the glaze dry completely and re-suspend it in
demineralized water,
just to see what would happen. Do not use all of
the batch, just
a part of it.
If the reaction leading to the formation of
hydrated calcium borates
is reversible, then it may help.
Later,
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/potier/172943983/
http://www.flickr.com/photos/potier/172941969/
----- Original Message -----
From: "Alisa Liskin Clausen"
To:
Sent: Friday, July 07, 2006 5:10 PM
Subject: Re: How to preserve glazes containing
high boron frits.
> >Alisa,
>>
>>Smart says he has no idea about your yellow
>>glaze,
>>probably due to the fact he does not have the
>>formula.
>>
>
>
>
> Not a surprise either, as I have no idea myself.
> Pesky problem with
> premixed glazes off the shelf. I only assume it
> is 90 Frit, 10 Kaolin and
> a stain. Only because this is the base the
> supplier recommends, but their
> own mixture could be a highly guarded secret.
>
> I am pleased however, feeling rather smug
> actually, that M. Smart has
> given me a good piece of information pertinent
> to a problem that has
> puzzled me, which I can take home and discuss
> with my colleagues. It will
> be interesting to see if sieving the glazes
> helps smooth it out in the
> firings.
>
> I had been looking for cyrstals on the surface
> of my glaze buckets that
> get quite cold in the winter, to see if I could
> capture them and fire them
> on the surface of my dipped pots (John Britt).
> Nothing last winter so
> will have to try it again this winter. But
> first must remember to enjoy
> this brief warm season.
>
> Perhaps people who Raku a lot have opinions on
> this theory to share here?
>
> Best regards, Alisa in Denmark
>
> ______________________________________________________________________________
> 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.
>
Ivor and Olive Lewis on sat 8 jul 06
Dear Alisa Liskin Clausen,=20
After reading Smart's article, the thought came to me that, rather than =
trying to redissolve the crystalline material or breaking it down by =
sieving, it would be preferable to ball mill the whole batch for an hour =
or so using Silica pebbles.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Alisa Liskin Clausen on sun 9 jul 06
>
>After reading Smart's article, the thought came to me that, rather than
trying to redissolve the crystalline material or breaking it down by
sieving, it would be preferable to ball mill the whole batch for an hour
or so using Silica pebbles.
Dear Edouard and Ivor,
I am thinking that for the sake of getting together some data, I will do
both the ball milling and the rehydrating method suggested by Edouard. I
hope to have some results to give back by the end of the summer.
It is very exciting to have some ideas about a problem I thought was
random, but knew there must be a reason, however, had no idea where to
start looking for causes. It had really been bugging me, this bubbling.
Curiosity and interest leads to the power of knowledge. Shared knowledge
gets us ahead in our craft.
Thanks and regards from Alisa in Denmark
Decided to stay in NJ until August 4
good the the pots at home have a long shelf life...the world will still
turn if I stay here at my mother's another 10 days.
Edouard Bastarache Inc. on mon 10 jul 06
Ivor,
Smart's last comment :
"C'est une solution a essayer pour ceux qui
possèdent un broyeur à billes,
mais cela ne fera pas disparaître le borate de
calcium, il sera seulement
divisé plus finement ce qui risque de produire une
multitude de très petites
bulles et donner un aspect "piqué" à la glaçure si
le dégazage ne se fait
pas totalement pendant la cuisson.(Smart)
It is a solution to test for those who have a ball
mill, but that will
not make calcium borate disappear, it will only
make it more
fine-grained which risks to produce a multitude of
very small
bubbles and to give a "piqué" aspect to the glaze
if degasification
is not done completely during firing.(Smart)
Edouard Bastarache
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/potier/172943983/
http://www.flickr.com/photos/potier/172941969/
Ivor and Olive Lewis on tue 11 jul 06
Dear Edouard Bastarache,=20
There is a difference between "Calcium Borate" and a "Calcium Borate =
Frit" . The former is a compound that may contain water of Hydration =
which could induce porosity in a glaze. The latter should be anhydrous =
and should not react chemically with water. It should be of a glassy =
structure.=20
Ball milling should take the grain size down to minus 200 mesh. This =
should be fine enough to disintegrate any crystals that have grown =
during storage. It was after all only a suggestion.
Calcium borate should disappear, for the most part, as a compound it is =
used as a fix to encourage fusion. There are better ways of doing this =
though the cost may be higher.
Best regards,
Ivor
Edouard Bastarache Inc. on tue 11 jul 06
Ivor,
I will forward your message to Smart.
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/potier/172943983/
http://www.flickr.com/photos/potier/172941969/
----- Original Message -----
From: "Ivor and Olive Lewis"
To:
Sent: Tuesday, July 11, 2006 3:53 AM
Subject: Re: How to preserve glazes containing
high boron frits.
Dear Edouard Bastarache,
There is a difference between "Calcium Borate" and
a "Calcium Borate Frit" . The former is a compound
that may contain water of Hydration which could
induce porosity in a glaze. The latter should be
anhydrous and should not react chemically with
water. It should be of a glassy structure.
Ball milling should take the grain size down to
minus 200 mesh. This should be fine enough to
disintegrate any crystals that have grown during
storage. It was after all only a suggestion.
Calcium borate should disappear, for the most
part, as a compound it is used as a fix to
encourage fusion. There are better ways of doing
this though the cost may be higher.
Best regards,
Ivor
______________________________________________________________________________
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
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