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Jeremy Ayers

c6 glaze too soft

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I have this lovely off white glaze c6 that I've been using for awhile but its too soft.

It will mar slightly with a knife. I'm not very strong in glaze calc - I"ve messed around with some other fluxes but haven't gotten any results for a better melt.

I fire to c6 via the programmed firing with a half hour controlled cool down to 2130 on my Skutt kiln.

I would love any advice on getting a better melt with this glaze without effecting the color and finish too much.

OFF WHITE

Neph Sy 59

Dolemite 19.5

Zircopax 14.7

OM4 Ball 2.4

RIO            .9

G Borate 10

Bent        2

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Undersupplied in silica as it is. You could add silica to it but it's going to gloss it up a bit. I like this dolomite recipe blended with clear to fine tune the balance between amount of gloss/matteness and no cutlery marking. If you have a clear that fits your clay just use that for the clear for the line blend.

Your recipe with silica just brought up to the bare minimum amount needed would be recipe 2 in the screenshot below. I kept everything else balanced the same as in your original recipe. Welcome to the forums!

5a90da58727c2_ScreenShot2018-02-23at7_16_18PM.png.d688eede99edd3ea27e009831228e480.png

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Hi Min -

I appreciate your expertise!

This is awesome, thank you. I will try this version out this week.

How much do you think this will effect the movement of the glaze? 

 

If you don't mind I have another glaze that I have a  similar problem with - its a glossy black that is nice looking but scratches easily.

Black

silica 27

EPK 17

Minspar 21

F 3134  26

Talc  3

Whiting  6

Bent     2

RIO   9

Cobalt Carb 2

 

Many thanks!

 

Jeremy Ayers

 

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9 hours ago, Jeremy Ayers said:

How much do you think this will effect the movement of the glaze? 

 

Have to try a test tile and see, but should be okay. It's not going to be as matte as the original. (that other recipe I linked to is terrific when blended with a bit of clear or white gloss glaze then add zircopax to whiten)

9 hours ago, Jeremy Ayers said:

If you don't mind I have another glaze that I have a  similar problem with - its a glossy black that is nice looking but scratches easily.

Looks like the Ron Roy Licorice Black recipe that has minspar in place of custer and a little difference in the talc and calcium carbonate. Doesn't look that far off the original which leads me to wonder if maybe it's just a bit underfired? Are you using witness cones? 

I ran it through Insight just to compare it, recipe 1 is your recipe as posted, recipe 2 is as close as I can get it to the original Ron Roy Licorice but using minspar and not custer, not a lot of difference. (for recipe 2 I took the custer version of Licorice and subbed minspar and adjusted materials where necessary) Licorice as published in Mastering Cone 6 Glazes is used by many people without reports of scratching, think I would just use that recipe.

 

 

 

 

Screen Shot 2018-02-25 at 7.15.02 PM.png

Edited by Min
added a thought

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In the first recipe, the zircopax may be the cause of the cutlery marking. Search zircopax on digitalfire.com and you will see more info on this. I would try a line blend of the glaze, reducing the zircopax to see how much is necessary to opacifiy your glaze. Then I would add silica in 5% increments to see how much the glaze could take before adverse effects arise. Also the first recipe that Min posted is a glaze I am testing right now. The matte surface of that glaze has an opacifying effect on its own, requiring less tin or zircopax to achieve the same opacity of your current white.

Edited by triolaz

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