Lewis on tue 9 sep 03
I am now the happy possessor of a copy of 'Mastering Cone 6 Glazes', =
that
wifey brought back from her sojourn to Minneapolis. She got a
grand-daughter, I got the book: good deal!
I see two things I need to change in my firing practice (not that I've =
had
much yet): a) soak and b) slower cooling. My controller can't control =
the
cooling rate, so I will follow the advice of setting the controls to
'medium' as soon as 'cone' is reached. But this brings me to my primary
question about soaking: do I soak *when* the cone is reached or *so =
that*
the cone is reached at the end of the soak?=20
If I soak for say 30 mins *when* the cone is reached, then it seems I =
must
be "overfiring"? For example, the Orton ConeCalc programme suggests =
that
if one is soaking for say 30 mins at Cone 6, then the firing temp should =
be
around 33C cooler (YMMV). The same program suggests that 'soaking' for =
30
mins at 'Cone 6' (say 1220C) will result in an effective Cone 7 firing. =
=20
What about the effect of slow cooling (of say 100C/hr instead of the =
initial
plummet of 100C/min)? Does this contribute to the heatwork? =20
I'm assuming (from the pictures of 'repeatable' cones in the book) that =
I
should aim to achieve an appropriately bent Cone6 *with* the combined
effects of slow final heating, soak and slow cooling. I'd welcome
confirmation!
Thanks VM
Lewis
Cat Yassin on tue 9 sep 03
In a message dated 9/9/2003 10:47:51 AM Central Daylight Time,
lewis.ramage@NTLWORLD.COM writes:
> I'm assuming (from the pictures of 'repeatable' cones in the book) that I
> should aim to achieve an appropriately bent Cone6 *with* the combined
> effects of slow final heating, soak and slow cooling. I'd welcome
> confirmation!
Lewis, it all depends on the glaze! I have some "Cone 6" glazes that actually
look better at a firm 7 (after the soak). And then again, I have some Cone 6
glazes that do better at a firm 6 (after the soak) which means I start the
soak when the cone 6 is slightly bent. I have to say though, most of the Cone 6
glazes I use look better with a soak as opposed to no soak. But you'll have to
test a couple times to find out which glazes do better at a longer soak. For
instance, I've heard that Ron and John's Raspberry does better at a cooler temp
and yet I've had it turn out lovely at a hotter temp than recommended. I
guess it all depends on who's firing and and the kiln, so many variables to
consider. Good luck :)
-Cat Yassin
Rick Monteverde on tue 9 sep 03
Lewis -
Just trying to figure this out too, so I hope my comments help.
>[...] do I soak *when* the cone is reached or *so that*
>the cone is reached at the end of the soak?
Isn't it hard to soak 'up' to a given cone? If you were just a bit too cool=
it could take a really long time to hit the cone?!
I just tried firing down for the first time last night from ^5. With the=
controls set to 'medium' just after sitter shut-off, instead of falling=
fast off the high temp point it fell at less than 100deg/hr. I also kept a=
very close eye on the witness cone to make sure it didn't overfire. Cooled=
over several hours to around 1800 on the pyrometer before I shut it off to=
cool normally.
>What about the effect of slow cooling (of say 100C/hr instead of the initia=
l
>plummet of 100C/min)? Does this contribute to the heatwork?=20
The ^5 witness on this firing bent only slightly off the curve it had when=
the sitter tripped. That's what makes me think it would be pretty hard=
going up the other way with any repeatability or accuracy. Hopefully that=
little extra heatwork gave the glazes more time to stew in their juices and=
grow pretty. Kiln's still cooling now, but I can see through the peeps that=
at least some of the glazes glossed up and moved well this time. Hope it=
worked, because I'm getting pretty frustrated - I'm about to station the=
trash can permanently next to the kiln!
@#!#% newbie hell...
-RM
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