[Clayart] Homemade Cone 5 and 6
robertgharris at gmail.com
Tue Apr 12 16:49:50 UTC 2022
And the frits probably contain Bismuth and/or Zinc for the 022-014 range.
While bismuth trioxide is yellow, the subnitrate is white.
And Digitalfire suggests that Bismuth compositions can have a softening
point as low as 390C/734F.
On Tue, 12 Apr 2022 at 10:37, Robert Harris <robertgharris at gmail.com> wrote:
> I imagine the low cones are mostly fritted.
> On Tue, 12 Apr 2022 at 05:13, David Hendley <farmpots at eastex.net> wrote:
>> On 4/11/2022 10:07 AM, ronroy at ca.inter.net wrote:
>> > I visited the Orton cone factory way back when. I'm pretty sure they
>> > were using red art clay. You will notice that the lower cones are
>> > redish - like the colour of red art - so there will be iron present to
>> > help melting at lower cones.
>> > I was asking questions - like how do you get the same result when red
>> > art is so
>> > variable? They told me they made a batch, made some cones and fired
>> > them next to standard cone they had lots of. If the cone did not bend
>> > properly they adjusted the batch and tried again - till the batch was
>> > right.
>> > If red art is used make sure you get a bag and reserve it for making
>> > cones.
>> > RR
>> Yes, I use Redart clay for for my cone 06 cones. Since Orton cones are
>> red in that
>> temperature range I decided to make mine red as well, by using Redart.
>> My formula and recipe is:
>> CaO .65
>> MgO .07
>> K2O .11
>> Na2O .17
>> Fe2O3 .08
>> B2O3 .72
>> Al2O3 .31
>> SiO2 2.22
>> Redart clay 48.5
>> Custer feldspar 9.0
>> Gerstley borate 28.0
>> whiting 10.5
>> total 96.0
>> I have been using the same batch of Redart (not just for cones) for more
>> 30 years, since I bought 4 bags in about 1990!
>> So, what ingredients are used for really low temperature cones?
>> When you get down to the luster firing range, cones 018, 019, 020,
>> the cones are white again, as are high fire cones.....
>> David Hendley
>> david at farmpots.com
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