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Friday, January 29, 2010

Some Results

Trust me ! It's been an uphill struggle, but i think we're close to the top !!!
Scuze my long abscence please.
My computer's been acting up . . . .
Have been firing every day . . . .
Glazing every day . . . .
Trying out new color combos . . . .
Here are some pretty poor photos and a really beautiful pot . . . .
( Should redo the photos but need to run check on the kiln, so here they are with all their warts.) Sides that - it's a bit challenging to photograph mostly black pots !
Have a greatest day
Chae


Wednesday, December 9, 2009

Unbelievable !!!

The only thing going thru my mind right this instant is: this is totally unbelievable !!!
Unaccountable, without rhyme nor reason, illogical, implausible, mind-boggling, unbelievable.

For 3 years, i've tried to get my gas kiln to reach temps even approximating 2167 °F. Have prayed, sworn a blue streak, researched extensively, and with a heck of a lot more patience than my personality type normally exhibits - tried, tried and tried again.

Finally, as most of y'all know, decided to modify all my glazes down to ^01 which this kiln will do with ease.

Overnight temps here in the valley reached a high of minus-12 degrees last night and by 6am twas only basically zero. In the attached garage, the temperature gauge read 15 degrees. Figured that was too cold for the electric kiln's digital-programmer to function.
Guessed that i could figure out how to run the gas kiln in straight oxidation.
Have never tried this before. Gas kilns are for reduction firing, right?

Oughta mention here, that i always stack a kiln immediately before using. Otherwise the glazed pots sit in the house where normal temps range at 68°. Carried them out to the garage, loaded the kiln (which was icy cold) and started the pilot. Normally, the kiln is run on pilot for 2-hours before turning the main burners up.
But this is very early am and i'm not quite awake. It occurs to me, that pots which are already 68° might not survive being rapidly cooled to 15° and then reheated.
There was also the kiln factor. Figured the pilot burner was not going to heat that kiln much above the garage temps.
So!
Cranked on the main burner just as low as it would go and waited. Two hours later, it was holding at 1000°F. Pushed the main lever ¾'s open with the draft completely uncovered and all ports open. (Trying for oxidation.)
From past experience, was expecting that in about another 2 hours, temps would have reached around 1827° . Of course, in the past have gone for body reduction at ^012 or around 1550 - 1620°.

Ah but no, the Cosmic Joker was messing with my mind but once again !!!
The thermocouple in the top port read: 2400°F ! The middle port temps were: 2350°F

Just couldn't believe what my eyes plainly saw. Stood for several minutes switching the thermocouples from one port to another - top, bottom, middle. Letting the thermocouples reach room temp and reinserting them into the peephole ports.

Yep! They actually did read 2400°F at the top; 2350°F at the middle.
And climbing !!!

The glazes are going to be fried, of course. More pots to add to the reject pile which is growing well-nigh out of hand. And actually, until the kiln can be opened tomorrow - am not even sure the Cone 6 clay didn't melt to puddles in cone 10 temps !!!

Main question here is: is this a fluke? Somehow related to the zero temps outside? Or is this a repeatable operation?
Chae

Thursday, November 19, 2009

Washes Over Thrice Fired Pots

Do not put a 50/50 Gerstley Borate and Frit 3134 wash over very dull, matt surfaces and fire them to 1888°F in a gas kiln hoping for better than previous results!
This does not work a'tall !!!

Wednesday, November 18, 2009

Glaze Combo

This is an awesome glaze combination at temps 2020°F electric oxidation firing.

50 Frit 3419
10 Neph Sye
5.5 Fireplace Ash
3 Lithium
9 EPK
14.7 Silica
5.4 Whiting
Plus:
1 Cobalt Carb
3 Lithium
2 Tin

Apply first, then apply the following glaze over this.

52.5 Frit 3124
9 Silica
14.7 EPK
4 Lithium
10.6 Zinc
7.8 Custer feldspar
5.4 Whiting
Plus:
1/2 Copper Oxide
2 Lithium
1/2 Cobalt Carbonate
2 Tin

Note: i measure in parts, using 1/8th teaspoon as a base measurement, so all of the above portions are in 1/8th tsp measurements.

Firing schedule:
200°F to 300°F
324°F to 1250°F
Full to 2000°F
Hold 15 minutes (see notes on this in previous post)
Full to 2020°F
Hold 20 minutes
Full to 900°F
Hold 40 minutes

Be aware: Both of these glazes run like crazy.
Note: by adjusting the tin oxide amounts in the additives, one can achieve different shades of blue yet with the same startling effects of the two glazes combined.


Ignore the outside of these pieces (these were all glaze tests and i usually try 3-4 per cup). Focus instead on the inside blues. Guess i oughta mention, ignore the quality of the photographs too!
For these are richly saturated blues with riverlets of blue, green, black and wee specks of pink adding a "richness" and depth to the overall finished glaze.
Happy glazing days to y'all
Chae

Sunday, November 15, 2009

Nother Glaze Database

Good Sunday Mornin' to y'all

If you're trying to find low-fire glaze recipes, this is an extremely useful database !!!
http://lindaarbuckle.com/handouts/glz_hg_lowfire.txt

Many thanks to Linda Aarbuckle, who has spent many hours compiling it !!!
She, also, has a raku recipe database. Just replace the word lowfire with raku in the address bar to reach it, then add it to your favorites list.

Way down towards the bottom of the list, there are some recipes for lustre glazes, too !!! Haven't tried them out yet but now that i can no longer find a source for Amaco Gold Lustre, will be attempting some of them in the near future.

Happy glazing days
Chae

Sunday, November 8, 2009

Glaze Worth Mentioning

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If you are working in the 2020°F glaze firing range, this glaze works well. It strongly resembles a "floating blue". The color is much more saturated and a richer blue than my photo shows.
It's a high Gloss where applied thick and doesn't run. Oxidized, electric firing.
Base Glaze:
52.5 Frit 3124
14.7 Silica
9 EPK
3 Lithium
7.6 Zinc
7.8 Cornwall Stone
5.4 Whiting
Plus:
2 Tin Oxide
2 Lithium (that's in addition to the 3 in the base glaze)
1/2 Cobalt Oxide

Note: i measure by parts. And use 1/8th tsp as a base measurement. Thus: 1/2 cobalt oxide would be: 1/2 of 1/8th tsp. Plus: i halved the above base recipe but didn't half the additives: tin, lithium and cobalt oxide.

I was seeking a pink. Spozedly lithium and cobalt oxide will produce a pink. But this didn't.
Still -- am quite pleased with the "floating blue". It's a keeper.
On the inside: Where applied thin, it's a steelish blue; the areas where 2+ coats were applied are the sections it "floated". Plus, (on the outside) where applied over a yucky chocolate brown glaze, it covered it well but the double-glaze is nothing to write home about.

Firing schedule:
200°F to 300°F
324°F to 1250°F
Full heat to 2000°F
Hold: 15 minutes
Full heat to 2020°F
Hold: 20 minutes
Full ramp speed drop to 900°F
Hold: 40 minutes

Explanation: the only reason the hold is between the 2000°F and the 2020°F, is because my Paragon kiln doesn't operate as it should and shuts itself off !!! Thus, i added an un-needed hold in order to coax it to reach 2020°F and this seems to work for this kiln. If i were firing a normal kiln, i would fire at full heat straight thru from the 1300 to the 2020°F. However, if my kiln operated correctly, i would be firing to Cone 6 !!! instead of recomputing all my glazes to the lower temp.
Chae

Wednesday, November 4, 2009

Fiddlin' Around


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Have recently been teaching clay classes.
Decided that having a theme would move the classes along in a somewhat orderly progression.
Chose musical instruments.
Had already started this banjo as a model for the first class, when i realized, much to my dismay, that it surpassed the abilities of the enrolled age group.
So!
Have spent the last couple of weeks remodifying my game plan.
We're still doing musical instruments.
Just on a drastically more basic level.
Still, without the motivation of teaching classes, it would never have occurred to me to try and create a banjo !!!
The tuning pins were a bit of a logistics problem. But think i have this solved.
The next challenge is: how in the world to i prop this upright in the kiln? If it warps a'tall, i'll be in the soup.
Have a day or two to figure this out while the clay dries before bisque firing . . . .
Am just a'hopin and a'prayin that it survives both the bisque and glaze firings, and then, actually makes music !!!
Chae