Reitz Green without Gerstley Borate?

[davidh4976]

I've been making good progress converting our glazes that have Gerstley Borate, Custer Feldspar, etc. The one that is eluding me is Reitz Green.  Anyone have a version that doesn't include the no-longer-available ingredients? (I've checked Glazy.org and only found one, but it has no photo. https://glazy.org/recipes/449)

 

[Min]

Is it just the tiny bit of GB you are replacing?

[davidh4976]

9 hours ago, Min said:

Is it just the tiny bit of GB you are replacing?

Yes! And, you would think that would be easy! Even with test pieces side-by-side in the kiln (one with GB, one without), the conversions that I have tried are coming out more blue than green even with the exact same amount of cobalt carbonate and rutile.

[Mark C.]

Gillespie borate  is still around at some places as well as Custar-just need to look harder and stock up. IMCO in Sacramento Ca has the gellespie for cheap cost

Edited May 2 by Mark C.

[Min]

6 hours ago, davidh4976 said:

Yes! And, you would think that would be easy! Even with test pieces side-by-side in the kiln (one with GB, one without), the conversions that I have tried are coming out more blue than green even with the exact same amount of cobalt carbonate and rutile.

What have you supplied the boron with so far? Same really high alumina?  Same batch of rutile?

Edited May 2 by Min

[davidh4976]

I used Frit 3134 for the boron and modified the quantities of other ingredients to keep the chemistry as close as possible.  Same batch of rutile. Here is my latest attempt.

69.4      Nepheline Syenite

14.1      Petalite

8.9        EPK

4.8        Whiting

2.4        Ferro Frit 3134

0.3        Dolomite

0.1        Lithium Carbonate

1.0        Bentonite

2.0        Rutile

1.0        Cobalt Carbonate

[Min]

Is this the original you were using? I've also seen this with 1 rutile.

[davidh4976]

8 hours ago, Min said:

Is this the original you were using? I've also seen this with 1 rutile.

Yes, that's the Reitz Green we have used; with 2 rutile.

[PeterH]

20 hours ago, davidh4976 said:

Even with test pieces side-by-side in the kiln (one with GB, one without), the conversions that I have tried are coming out more blue than green even with the exact same amount of cobalt carbonate and rutile.

Any relevance?
https://digitalfire.com/material/gerstley+borate
... at the bottom of the page, discussing substituting  Gillespie Borate  for Gerstley Borate ...
Clearly, the Floating Blue itself is firing greener than usual. And the Gillespie Borate version is much bluer. You may be used to something in between these two. The green tones could likely be restored by a reduction in the cobalt and increase in the iron oxide.

Edited May 3 by PeterH

[Min]

Good find Peter.

When I look at the analysis for both there are other differences too though. Definitely a fragile mechanism to get the green. Reitz Green with Gillespie doesn't need the lithium carb and dolomite additions when I played around with altering the recipe, the silica is a tiny bit higher in the Gillespie version but given the differences in the Floating Blue recipe that might or might not be consequential, I don't know. 

A simple addition of iron with a reduction of cobalt would be simple to test Hansen's theory if it translates to Reitz Green also. I suppose RIO would be the logical material to add as long as speckles don't become an issue. Or black iron oxide might be better if you have it.