John Sankey on tue 15 jan 08
For my iron glaze studies I'm hitting a problem, that I need more
alkali (R2O) that is free of RO and all such sources seem to be
water soluble. Applying such materials in the usual manner will
result in the R2O soaking into the bisque and I won't know the
composition of the final glaze.
Has anyone tried mixing small test amounts of glazes and applying
them dry to a horizontal tile?
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Bill Merrill on tue 15 jan 08
I have never seen so interesting issues people are having with
materials, glazes or clay bodies.=20
=20
John, =20
=20
What quality of iron are you using? What suits me best is a 97% iron
that is a beautiful red from the sack. I sent out the formula Volkous
slip with 75% iron in it. If used thin, like a wash it will go over a
glaze. If a little thicker it is great on a body, with glaze over it.
=20
Sifting glaze on a pot works (I use wood ash on a glazed pot. In fact
when using Shino I sometimes put some ash in my hand and blow it on a
wet glazed pot.=20
=20
Bill
=20
=20
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of John Sankey
Sent: Tuesday, January 15, 2008 8:06 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: dry glaze application
=20
For my iron glaze studies I'm hitting a problem, that I need more
alkali (R2O) that is free of RO and all such sources seem to be
water soluble. Applying such materials in the usual manner will
result in the R2O soaking into the bisque and I won't know the
composition of the final glaze.
=20
Has anyone tried mixing small test amounts of glazes and applying
them dry to a horizontal tile?
=20
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Include 'Byrd' in the subject line of your reply
to get through my spam filter.
=20
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Ivor and Olive Lewis on wed 16 jan 08
Dear John Sankey,
You have a problem...<< For my iron glaze studies I'm hitting a problem, =
that I need more alkali (R2O) that is free of RO and all such sources =
seem to be water soluble. Applying such materials in the usual manner =
will result in the R2O soaking into the bisque and I won't know the =
composition of the final glaze.>>
I suggest you try Cryolite, Na3AlF6. Fusion point just above 1000 deg C. =
Insoluble in water. Difficult to make any calculations with this because =
of the absence of Oxygen. But it is a well used flux in the Aluminium =
Industry where it is employed to Flux Bauxite.
Albite and Nepheline Syenite should have very low CaO fractions. They =
will give you the R2O fraction you need.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Daniel Sommerfeld on wed 16 jan 08
John,
Maybe you could mix it with a solvent. I'm looking at a canister
of "plastic wood" which is a fast-set wood filler. The label states it
contains "acetone, n-butyl acetone, and isopropanol.
Or how about a light oil or a possibly a wax.
At this point I'm ignoring the interactions with these ideas and the glaze
ingredients - just throwing out ideas.
How about this idea: Coat a piece of paper with the glaze and then let it
dry and place it on the test tile. This would add a small amount of paper
ash to the mix, though. Or maybe add a binder like some flour and egg to
the glaze and coat it onto wax paper. Once it sets the "film" of glaze
may be able to be burnished onto the bisque.
Just some crazy ideas.
Good Luck,
Dan Sommerfeld
www.byhand.us
John Sankey on thu 17 jan 08
Many thanks all for the replies. As I replied to the first
suggestion, which arrived offline, 90% of research success is due
to a researcher thinking around a mental block that others have
had. (Have you ever seen a recipe that doesn't use water? I
haven't!)
Olive oil works fine. I'll just give it some extra time at 350C
to oxidize the carbon before things start to melt. (My kiln room
has a 200 cfm exhaust fan.) Here's the protocol I'm planning:
Each tile glaze will be made with four 2.5 ml measures of dry
material mixed with olive oil to a brushable paste. Target is
3.5 Seger SiO2, 0.4 Al2O3, 0.25 B2O3 (B2O3 and FeO omitted from
Seger ratios as per MC6G).
Using line blends with base of 0,25,50,75,100% of each glaze
component) singly (3 series), in pairs (3,3/2), and together
(3,1/3) plus 1 of each with 1% cryolite for fluorine tests
requires 185 ml of base and 55 ml of each of the others.
base molar Seger
29 silica 0.613 3.570 SiO2
27 potassium carbonate 0.102 0.592 FeO
22 kaolin,EPK 0.158 0.923 K2O
10 iron oxide,red 0.011 0.065 Na2O
10 frit,Fusion 367 0.068 0.397 Al2O3
2 Bentonite 0.045 0.259 B2O3
phosphorus 0.033 0.194 P2O5
27 silica 0.588 3.476 SiO2
26 potassium carbonate 0.100 0.593 FeO
21 kaolin,EPK 0.157 0.926 K2O
15 iron phosphate 0.010 0.061 Na2O
9 frit,Fusion 367 0.067 0.396 Al2O3
2 Bentonite 0.041 0.243 B2O3
calcia
24 kaolin,EPK 0.617 3.469 SiO2
32 silica 0.166 0.931 CaO
22 calcium carbonate 0.094 0.530 FeO
10 frit,Fusion 367 0.010 0.058 Na2O
10 iron oxide,red 0.069 0.387 Al2O3
2 Bentonite 0.041 0.232 B2O3
magnesia
39 salt,Epsom 0.597 3.538 SiO2
18 kaolin,EPK 0.122 0.726 FeO
23 silica 0.156 0.925 MgO
10 iron oxide,red 0.011 0.065 Na2O
8 frit,Fusion 367 0.068 0.405 Al2O3
2 Bentonite 0.043 0.255 B2O3
Waiting for materials to arrive.
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