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Anyone Know A Similar Glaze For Cone 6 Oxidation


oldlady

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this glaze came from my friend Robin Teas while she worked at Lord Fairfax comm. college in va.  it was her recipe and fired in a gas kiln.  i know the pinkish effect is from reduction firing but i wonder if anyone has a glaze recipe for something matte, green and able to show fine texture without flattening it out.

 

Robin has given me several recipes to try but it does not hurt to ask the whole community the question.

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This glaze may be better at cone 6 as a combination of two glazes, a cone 6 raspberry with a copper green. I have no idea how you could do it without two glazes of this sort. I think I would start with something like Van Gilder's raspberry, and some green that is semi transparent.

 

best,

Pres

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i am not trying to get the pink,  i am looking for a matte green able to show fine texture without flattening it out.  at cone 6 .   in oxidation.

 

 

Spearmint does not work.  i have strontium green.  i have oribe green, too glossy.  i will try Wettlaufer's 18 which is a really nice matte glaze.  i have tried it with 4% copper, which is very dark.  will try 3%.   

 

 any other suggestions?

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Hi, there's Helens Olive Matt/Soft Red
Cone 6-9
Reduction or Oxidation
 

Nephelene Syenite 75
Whiting 10
Dolomite 10
Bentonite 4
Silica 5
Copper Oxide 2
 

Comments: Cone 5-6 (electric kiln, oxidation) gives Olive Matt; Cone 9 (electric kiln, oxidation) gives Green/Orange Gloss; Cone 9 (gas kiln reduction) gives Soft Red Gloss.

You could try lowering the copper as it might be a bit dark.

 

Dee

.

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nerd, sent you a pm.

 

dee, do not think i have copper OXIDE, i always use the carbonates because the oxides are so strong.  even as a carbonate, copper is strong.   will try this recipe, today is another glazing day.

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We use a very pretty satin turquoise that doesn't get the pinks as much but on brown clay changes from orange to turquoise very subtly. It pairs well with other glazes as well. I use it as a staple because it looks very different (but still very good) on my 2 different clay bodies.

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Lady:

 

My first attempt at red in ^6 oxidation:

 

 

Red/ deep green just barely coming through.

 

Second attempt at red in ^6 oxidation

 

 
2 hour soak involved.  Forgot to titrate PH downward- crawling -opps!!
 
Should have something for you shortly.
 
Nerd
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thank you, rex.  i mix my own glazes and this will be a color i will use on a hundred pieces so buying it would be prohibitive.

 

nerd, thank you, hope it works.  again, i am not interested in the pink, just a nice matte green that allows texture to show through.  so many matte glazes flatten the surface totally so nothing shows from all the work i do to put the texture on.  leaves do not make deeeeeep impressions.

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  • 4 weeks later...

as of august 26, 2016

 

dee3 and anyone else who might try Helen's olive matte glaze shown above. thank you, dee3, it turns out that the recipe is in my glaze book but it is one i had never tried.  added the attribution to Helen though i do not know who she is.  

 

it is a beautiful color, the glaze is easy to make but it does powder off when handled to place in the kiln.   i tried it on 2 different shapes both inside and out.  sadly, all of the tests have crazing way down inside the glaze.  i can't see the crazing on the surface, but it is there.  the color is not so olive as the name suggests but i like the color.  it does seem to cover texture but i am not sure if it would be too much.  the pattern i drew into the test bowl disappeared.  am out of room for photos right now, i thought they added more capacity during the last website revision but i am wrong.  

 

can anyone suggest a modification to prevent the crazing?

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Hi, there's Helens Olive Matt/Soft Red

Cone 6-9

Reduction or Oxidation

 

Nephelene Syenite 75

Whiting 10

Dolomite 10

Bentonite 4

Silica 5

Copper Oxide 2

Not surprised at all to see clay/glaze interface checking  Nep SY has one of the highest COE values among fluxes. The above recipe has an estimated COE value of 9.25  ( some programs post it as 92.50)  Well above any porcelain or stoneware COE values. In addition, the NaK20 are way over formula limits set by Hesselbeth and Roy. It is an extremely fluid glaze: which in your case is desirable so that it flattens out uniformly over the detailing work. By reducing the Nep Sy, you likewise lower the COE: which brings it in line with most clay values. By replacing it with silica: you still have a fluid glaze that should flatten out equally as well. The above recipe falls seriously short in regards to silica formula limits: so silica additions are required to conform to minimum formula limits. That said:

 

Nep Sy         50.0

Dolomite      15.0

Whiting         11.0

Bentonite       4.0

Silica             24.0             Est COE   8.09     (a full point under the original recipe: which should cure the grazing issue.)

 

Did not mess with copper carb, it is a colorant that you will need to adjust to reach your desired hue.

 

Try mixing equal parts of EPK and Bentonite: and use that mix to replace the 4.0% in the recipe. EPK makes a good glaze hardener as well: might help with the powdering/flaking issue.  The additional magnesium in the dolomite will deepen the green a bit: might hit your olive hue better.

 

Nerd

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thank you, nerd.  i will try your suggestions.  it is great that you are willing to share knowledge in simple terms so even i can sort of understand.  will try that revised recipe.  

 

if i got it right, eliminate  bentonite  4 and use bentonite 2 plus EPK  2.

 

i did use copper oxide.  will try to adjust pics so i can send what happened but the guild picnic is here tomorrow and there is a LOT to do.

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if i got it right, eliminate  bentonite  4 and use bentonite 2 plus EPK  2.

Yes maam- but that revision is an attempt to help resolve the glaze dusting issue. If you see no benefit- go back to the straight 4% bentonite.

 

Here is the analysis of the glaze before, and after revision:

 

 

Original Recipe                    Hesselberth & Roy ^6 Limits                                                   Revised recipe

 

0.437                                    Kna(o)       0.10-0.30                                                              0.259

0.146                                    MGO         0.00-0.30                                                               0.209

0.416                                    CaO          0.20-0.60                                                               0.502

0.476                                    Al2O3       0.25-0.50                                                               0.320

2.28                                      SiO2         2.50-4.00                                                               2.43

 

Si/Al  4.80                                                                                                                    Si/Al  7.53

COE  9.25                                                                                                                    COE 8.09

 

Normally clay additions are often used to increase silica and alumina ratios. However, in this case I wanted the alumina lowered and the silica raised to increase the fluidity of the glaze so it will flatten out against the detailing.  The silica remains under limits in the revision: which is easily addressed later. See how it works first before making any additional adjustments. >>> I would recommend close attention be paid to application rate of the glaze: it will be fluid.

The increase in magnesium (MGO) should help with the "olive" hue you are looking for.

 

Nerd

 

Please recheck the revised recipe: I noticed a typo on the silica amounts.

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Bruce:

 

Yes it will. Playing a bit of a shell game here. Lady needs a glaze that will lay down, and not cover up her detailing work. So I kicked the legs out from under it by lowering the alumina, to offset the fluidity lost with removing the Nep Sy. I increased calcium and magnesium (low flow alkali) to replace the strength lost in the alumina. In addition, dolomite is used in glazes in higher percentages to help create the matte.(magnesium).  Hopefully the trade off works: might have to increase dolomite further. There are other matting agents that could be added as well.

I work glaze a bit different than most: I aim for the function first: then add the aesthetics. The additional magnesium should also help her hit the olive mark. Again, glaze application/thickness will be a crucial point. Oxide colorants like to pool in fluid glazes- trying to avoid that as well.

 

Nerd

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OK, nerd, if i understand it, my recipe now reads    neph sy                         50

                                                                                silica                               24

                                                                                dolomite                         15

                                                                                whiting                            11

                                                                                            total                    100

 

                                                                                bentonite                         2

                                                                                EPK                                 2

                                                                                copper oxide                   2

 

if that is correct, i will make it.   there is little time between now and sept 10 for testing tiny tweaks so i hope this is the solution, thank you.   will make it up tomorrow 

 

another note, the matte is nice but the color and the transparency is critical.  the test showed a nice matte going shiny.  will  add  photo!

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Lady:  you have it.  It will go a bit more glossy, but hopefully the additional mag will offset some of that.  Get a reg and close up pic if you can. The big adjustment will be the amount of oxide: that is solely a judgment call on your part. I expect it to be rather clear given the silica content. High levels of flux can cloud as well: that has been resolved as well.

 

Nerd

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Lady:

 

Still studying the pictures you posted.  You noted on the cup that a piece on the rim fell off (shivering.)? The first picture is what has my attention: it is a bit blurry, but I can see the COE issue you were speaking to: crackle/glaze. Am I seeing a color shift up on the rim to a tan color? If so, then you have a higher iron content clay- stoneware perhaps. What kind of silica are you using?

 

Nerd

 

You might want to do a test with 1.50 and 1.75% copper carb.: green strikes me as being a tad strong.

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