Changing The Firing Range Of Porcelain

[Wyndham]

Hi folks, I've been gifted 700-800 lb of Highwater's P10 porcelain which will have to be remixed, no problem as I have a mixer.

What I'd like to do is reduce the maturing range to cone 6 .The specs say that the bottom range is cone 7 at 2.5 % absorption but the working at cone 10-11 is the optimum range.

I've noticed that some clays can be brought from cone 10 to a cone 6 with added flux, either g200 or nep sys.

Some of you here have made clays more that I have and thought someone might have some idea of a testing % of flux to add when I remix a batch for cone 6.

Thanks

Wyndham

[Biglou13]

Try adding 1 # nepsy to 13 pound clay

 

1.5 and 2 # for tests. (Scale down if desired)

 

Most cone 10 clays follow the traditional 25% spar ratio.

 

As always much of this is conjecture since clay formulas are secret.

 

Nep Sy is a lower temp flux, and may be easiest approach without other "accelerators"

 

As always testing is king. Did is say TESTING IS KING

 

I'd make some simple test tiles, bisque the cone six fire then test for absorbtion / vitrification.

 

There are some cone 6 porcelain (ish) formulas that go to 50% spar.

 

You'll want the minimum flux to get you to target absorbtion level.

 

If you want me to throw out a wild guess I'd say add 1.5# nepsy to 13 pounds moist.

 

The next issue is mixing. I wouldn't settle for less than slurry mixing clay to guarantee distribution. I don't hink Soldner or walker or miixing pugmill will work because the moist clay will resist even distribution of added flux.

 

Sorry it's getting complicated, but fixing things on back end always are.

 

I think 2.5 % is too open for porcelain body. Sub 2 % is better sub 1.5 is much better

[Wyndham]

If I could get it to 1.5 %, I'd be happy with that. I agree that slake and bake is better, which is really not a problem in the long run.

1lb to 1/2 bag(wet) is about 8% for dry.

Does that sound about right?

Wyndham

[Biglou13]

Yes I'm thinking 1.5# nepsy (my wild guess) To 13 # (1/2 bag ish).

 

Yes 1# nepsy is a good starting point. Let me know how it works.

 

The following is pure conjecture

1# should get you to 35% flux

1.5 # ...... 40%

 

I doubt you'll need it but maybe fire on saftey tiles just incase

[neilestrick]

I would do all the measurements dry if I were you, so you can have consistent results and accurate tests.

[bciskepottery]

Or maybe call Tech Support over at Highwater in Asheville and ask for their suggestions.

[Wyndham]

Yea, I have a call into them but the head clay guru is out today. It's also good to get different opinions and POV. I figured there are enough squirrels over(including me) here to get a bead on a cache of nuts, uh, ideas

Thanks Wyndham