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Comment by Joseph Fireborn on May 26, 2017 at 12:07pm

That is interesting. I noticed some of my glazes spec when I do a slower cool than I normally do. I want to try your schedule in the future. I might order some of that frit and compare original vs with frit at that temp rate. Thanks for the reply.

Comment by Norm Stuart on May 26, 2017 at 7:24am

The black dots in the slow-cooled glaze come from the glaze ingredients rather than the clay. It looks the same on porcelain.

Comment by Joseph Fireborn on May 26, 2017 at 7:16am

Norm in the picture below. The warm Jade Green. Are those two pictures on the same clay body?

Or is the one on the right a body with Manganese Granular?

I am curious about this Frit 3269. I might try some of it soon.

Comment by Norm Stuart on May 21, 2017 at 1:21pm

Barabara -  Even at a fast cool Weathered Bronze Green needed extra flux to become reliable.

But our need to add extra flux and glass, with the additional 20% 3269 Frit, comes from our use of a very slow-cool - 6 hours between 1,800 F and 1,500 F, so 50 F per hour.

This results in additional crystallization which give extra character to most glazes. This example of Randy McCall's Warm Jade is why we use the slow-cool.  This was an artistic choice we've used for the past five years to give Cone 6 glazes the look of Cone 10 glazes from a hard-brick kiln which naturally cools far more slowly than a soft-brick kiln. If I wasn't interested in chemistry and re-working glazes we probably wouldn't be doing this.

In some glazes though, like Weathered Bronze Green, this long slow-cool results in all of the glass being taken up in the form of matte mustard-colored crystals. Adding the extra 20% 3269 Ferro Frit adds glass and flux returning the glaze to the same look it had when the kiln cooled rapidly at it's normal rate.

Without our very slow-cooling schedule the extra frit may not be needed.

This is what the unaltered recipe for Pete's Seafoam Green looks like after our very slow-cool. Adding extra frit would likely make it look more like your bowl, or perhaps something else entirely.

These photos of Sapphire show what happens as the cooling through the crystallization temperature zone is slowed. Using our very slow-cool one-dip is fully crystallized and doesn't appeal to me. Two dips and three dips f Sapphire have a lot of character while still retaining some of the color of the fast cool tile.

Adding an extra 10% to 20% of a frit is will make the glaze glossier, although it might end up looking quite unlike the original as with this Clear Base Blue Recipe. Adding the extra 10% 3269 makes the glaze glossy again in a slow-cool, but quite a different glaze than the original.

Comment by Barbara Hanselman on May 21, 2017 at 12:00pm

Strontium Matte Seafoam

Comment by Barbara Hanselman on May 21, 2017 at 11:55am

When adding the 20% 3269 frit, do you eliminate or changer any of the other ingredients? The recipe I use for Weathered Bronze follows -

STRONTIUM WEATHERED BRONZE (Frog Pond Green)

This is a great weathered-looking glaze.  The bronze goes from a clear, bright green to a brownish bruised green and is suited to all clay body colors, although it is best on tans. 

60% Nepheline Syenite

20% Strontium Carbonate

1% Lithium Carbonate

10% Ball Clay-Old Mine #4

9% Silica

ADD:

5.0%  Copper Carb

5.0%  Titanium Dioxide

2.0%    Bentonite

This is a Pete Pinnell’s strontium glaze tweaked by John Hesselberth.  Needles to say, the fired color of both the Seafoam and Weathered Bronze are almost identical but the Seafoam glaze really goes on nicer and seems to fire more evenly.

Here's the Seafoam recipe:

Pete’s Seafoam Glaze ^5/6

9.6% Ferro Frit 3134

51.3% Feldspar-Kona F4

25.5% Strontium Carbonate

12% EPK

ADD:

5.0%  Copper Carb

5.0%  Titanium Dioxide

2.0%    Bentonite

Comment by Norm Stuart on April 27, 2013 at 11:44pm

Another artist using my Weathered Bronze Green with 20% Ferro Frit 3269 added and a blend of Lithium Fluoride, Lithium Cabonate and Lithium Chloride.

Still brown where the glaze is too thin, but much more reliable with a simple three coats.

Comment by Norm Stuart on March 25, 2013 at 7:07pm

These are the latest results, now adding 20% 3269 Ferro Frit to Weathered Bronze Green.

Being better fluxed, the glaze no longer requires thick coverage.

Ferro Frit 3269 is a high expansion "crackle frit" which adds Sodium and Potassium flux for brighter colors and expansion, along with Boron.

http://digitalfire.com/4sight/material/ferro_frit_3269_371.html

Comment by Norm Stuart on March 20, 2013 at 10:48am

Interesting. I making Weathered Bronze Green into a more reliable glaze for us by adding frit.

I've found the added Soda and Potassium of either Ferro Frit 3269 or 3110 can brighten a lot of glazes, especially any glaze that looks too dry. Adding 16% 3269 to Weathered Bronze Green is almost enough, 25% is too much, so some tiles with 20% go in the kiln next.

I've also made three batches, one with Lithium Carbonate, the second with Spodumene and the third with Lithium Fluoride. The tile with Lithium Fluoride (the most powerful of the three lithium fluxes as both the lithium and the fluoride in the molecule both act as fluxes) with the 16% 3269 Frit is obviously displaying the highest degree of melt.

I've seen Weathered Bronze Green fire to a light yellow, dark mustard, and black. With the added frit it's now coming out better. Three coats on the top 1/3, then two, and one towards the bottom. Obviously it comes out best in the dimples, so perhaps the glaze accumulates there.

I want a glaze that fires in our firing schedule with slow-cool to a reliable weathered bronze.

Lithium Fluoride, no frit, 3% 3269, 6% 3269, 16% 3269

Lithium Carbonate, no frit, 3% 3269, 6% 3269, 16% 3269

Spodumene, no frit, 3% 3269, 6% 3269, 16% 3269

Comment by Norm Stuart on March 19, 2013 at 6:24pm

I found it. Alisa Clausen's photo of Pete Pinnell's glaze is different to mine.

http://www.flickr.com/photos/glazes/1086339415/in/photostream/

My tile fired to Cone 6, 60 min hold, slow cool 50F per hour between 1,800 and 1,500.

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