Honey Flux glaze firing blue

[Nannette Pilcher]

Hello, I have encountered an issue with Amaco Potter's Choice Honey Flux turning blue with white highlights on a few of my pieces. 

We have been firing a chess set and most of the pieces have fired beautifully but on a couple of the loads, the pieces have been fired with an assortment of other various pieces. We are an art school so we have many artists creating but a select few people are in charge of loading and firing the kilns. We have been firing to come 6 and sometimes come 5.

The blue/white is beautiful, but not a match with the accurate Honey Flux. 

If anyone has had this particular issue and can provide some information on how to avoid/control the variation, I would be very grateful. Thank you, Nannette Pilcher 

[Babs]

Hi, would you upload images and poss the glaze recipe then folk will be able to work out what's happening. 

Fickle nickel can cause honeys to blue in some conditions.

[PeterH]

SDS at https://tinyurl.com/2csusk8r

Mentions:
Silicon dioxide
Calcium carbonate and dolomite
Nepheline Syenite
Rutile
Zinc oxide
... all max 15%

[Kelly in AK]

This is a complete shot in the dark with no photos and not knowing much about what’s in the glaze. It’s described as creamy and honey at cone 5, then fluid and white at cone 6. Sensitive to temperature differences. Probably sensitive to application thickness. It makes me think temperature and cooling rate may have something to do with it. A kiln packed full will take longer to heat and cool slower than a light load, something to consider.

That said, I’m speculating. The SDS listed rutile and calcium, but I didn’t see any source of boron, which seems to be the magic combination to produce blue via rutile. 

[Babs]

Rutile may do this, titanium dioxide opacifier, if dirty rutile may perhaps "leave behind" its impurities as temp goes up?

[Kelly in AK]

Until we get pics anything goes.  Maybe it’s the rutile. Maybe the clay body has an effect. Maybe…someone stirred the glaze with a brush that had been recently used to apply a cobalt wash. Maybe the person in charge of the firing did a 30 minute hold at the end for their piece. Perhaps a dish of cobalt oxide was being fired as a test and fumed everything in the kiln. What else can we think of? Art school. Anything can happen. (Been there, caused that, I’m sorry)

I’m guessing it’s just a peculiarity of the glaze. Potter’s Choice glazes are billed as being reactive and somewhat unpredictable (as a selling point), and creating special effects through layering different combinations. They seem to be a good example of trying to replicate in an electric kiln what happens in a reduction firing.

Surprises can be good or bad, but the truth is either way they beat the pain of knowing exactly what everything will look like every time you open the kiln. The surprises are what keep me going. 

[Callie Beller Diesel]

I think an important question is what other glaze is the Honey Flux being used with? It’s not supposed to be used alone. 

[LeeU]

I use Honey Flux "as is" and love it. This is Honey Flux "naked", single-fired, at cone 5 on a Dover White body...a little dish w/some shallow textural stamping.

[Kelly in AK]

Oh, I definitely see some faint blue opalescence forming there! Nice looking glaze, thanks for sharing a picture @LeeU.

[Nannette Pilcher]

Hello All, thank you for your insights and suggestions. Sorry for not uploading photos with my initial post, I was on my way out of town for the week and had not gotten photos before I left. The Honey Flux we are using is the commercial Amaco glaze on Anasazi 5 clay body.

The first 2 photos are of a base and a tile that my partner glazed and she thinned the glaze with water and used way too much water. We assumed that the over thinning of the glaze caused it to turn blue/gray.

BUT, the 3rd photo is of a pawn and the glaze was applied at the proper consistency with three healthy layers, like the other pieces that have fired correctly, yet it turned really blue.

I was not aware that the rate of heating and cooling would/could affect a glaze so drastically, firing temperature yes but rate, had no clue.

My initial thought was that maybe a different glaze on someone else piece may have reacted with the honey flux through fumes mixing in the kiln, is that even possible?

Anyway, we are not sure what has caused it to go so blue on a few and not on others (fired in separate batches) we LOVE the blue and would really like to know how to control the shift in order to use it when we want and avoid it when we don't.

Thanks again for your willingness to provide insights and suggestions, much appreciated. Nannette

 

[Callie Beller Diesel]

Aha! The clay body is a buff one, which means it’s both a thickness thing and a reaction with the iron in the clay. 

The simplified explanation is that whatever’s in honey flux, it behaves very much like a rutile blue glaze. The blue colour isn’t from a pigment, it’s from how light refracts back through the glaze and into your eyes. So thickness and the colour of the background the glaze is on will affect the end results. A thinner application and a lighter background will make this glaze look like it does on the Dover white clay example Lee posted above, and you can see what thickness did to your buff Anasazi. If you put this glaze on a red or black clay, you’d need only a very thin layer to get that same blue/white variegation effect that is on the chess piece in your last picture. 

If you want it to look like Lee‘s version, you’ll have to use a different clay, or apply a white slip/underglaze to your existing one. 

 

edited to add: given that the MSDS lists zinc in the materials, cooling time may be a factor as well. If the kiln pack was tighter on one firing than the other, that could also account for the difference. Zinc tends to allow glazes to stay more fluid for longer periods, giving them more time to either continue any chemical reactions or to just smooth out.