iandol on sat 30 nov 02
Hello again.
I would like some opinions about the observations made when we look at a =
series of test tiles.
It seem obvious that if the samples on a matrix test tile are =
transparent, smooth, glossy, water clear glasses that the mixtures from =
which they were formed have melted totally.
But is it possible to distinguish with the naked eye if those samples =
which are opaque are under cooked or are properly cooked and have thrown =
out a precipitate on cooling?
Another way to put it is to ask if opaque or translucent matt glazes are =
not really matured. How do you distinguish between a mature glaze and an =
underfired glaze when the observations are almost identical?
Best regards,
Ivor Lewis
Ron Roy on tue 3 dec 02
Hi Ivor,
If the glaze has melted you will see some movement especially where the
glaze is thick - you could put a line of cobalt under the glaze to see if
it will diffuse a little into the glaze.
Underfired matts do not smooth out properly so make sure there is some
uneveness in the glaze application.
A good way to judge all this is to partially double dip your test tile - if
the difference between double and single dip is still there - it probably
means underfired - if you can't find the line between the two it is well
melted.
RR
>I would like some opinions about the observations made when we look at a
>series of test tiles.
>It seem obvious that if the samples on a matrix test tile are transparent,
>smooth, glossy, water clear glasses that the mixtures from which they were
>formed have melted totally.
>But is it possible to distinguish with the naked eye if those samples
>which are opaque are under cooked or are properly cooked and have thrown
>out a precipitate on cooling?
>Another way to put it is to ask if opaque or translucent matt glazes are
>not really matured. How do you distinguish between a mature glaze and an
>underfired glaze when the observations are almost identical?
>Best regards,
>Ivor Lewis
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Wanda Holmes on wed 4 dec 02
Ron, does your method hold when firing the tiles flat? My experience
with tiles (vs. vertical surfaces such as a pot) is that unevenness in
glazing tends to remain visible. I also find that I have more success
with glazes that are less stiff - what might run off a pot works well
for me because I don't have gravity helping to even things out.
Wanda
-----Original Message-----
From: No title defined [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of
Ron Roy
Sent: Tuesday, December 03, 2002 5:28 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Glaze Test Observations
Hi Ivor,
If the glaze has melted you will see some movement especially where the
glaze is thick - you could put a line of cobalt under the glaze to see
if
it will diffuse a little into the glaze.
Underfired matts do not smooth out properly so make sure there is some
uneveness in the glaze application.
A good way to judge all this is to partially double dip your test tile -
if
the difference between double and single dip is still there - it
probably
means underfired - if you can't find the line between the two it is well
melted.
RR
>I would like some opinions about the observations made when we look at
a
>series of test tiles.
>It seem obvious that if the samples on a matrix test tile are
transparent,
>smooth, glossy, water clear glasses that the mixtures from which they
were
>formed have melted totally.
>But is it possible to distinguish with the naked eye if those samples
>which are opaque are under cooked or are properly cooked and have
thrown
>out a precipitate on cooling?
>Another way to put it is to ask if opaque or translucent matt glazes
are
>not really matured. How do you distinguish between a mature glaze and
an
>underfired glaze when the observations are almost identical?
>Best regards,
>Ivor Lewis
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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iandol on thu 5 dec 02
I have written in private to Ron about his response to my Inquiry.
I have only one open question as a follow up which someone may be able =
to throw some light on.
I am curious about the nature of the glaze which is underfired and is =
also matt.
If a glaze is thus, what is responsible for causing the mattness?
Hope to get some more thoughts from other people on this matter.=20
For people who may have missed my original posting which initiated this =
topic here is the information;=20
>I would like some opinions about the observations made when we look at =
a series of test tiles. It seem obvious that if the samples on a matrix =
test tile are transparent, smooth, glossy, water clear glasses that the =
mixtures from which they were formed have melted totally. But is it =
possible to distinguish with the naked eye if those samples which are =
opaque are under cooked or are properly cooked and have thrown out a =
precipitate on cooling? Another way to put it is to ask if opaque or =
translucent matt glazes are not really matured. How do you distinguish =
between a mature glaze and an underfired glaze when the observations are =
almost identical? >
Best regards,
Ivor Lewis. Redhill, South Australia.
On a Raining Day after a great view of the Eclipse.
Ron Roy on sat 7 dec 02
Hi Wanda,
Yes - glazes on a vertical surface do tend to smooth out better - and -
because tiles are flat on the shelf they need more time to heat up - it's
because the shelf needs more heat and the tiles get held back a little. A
longer soak will help but perhaps more melting is the answer if there are
other glazes that are working well.
Stiffer glazes can be fixed by adding more flux to the glaze - unstiffen it
a bit - not hard to do. Best to do it with calculation software keeping the
ratio and expansion the same.
RR
>Ron, does your method hold when firing the tiles flat? My experience
>with tiles (vs. vertical surfaces such as a pot) is that unevenness in
>glazing tends to remain visible. I also find that I have more success
>with glazes that are less stiff - what might run off a pot works well
>for me because I don't have gravity helping to even things out.
>
>Wanda
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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