Old Gold Albany Flakes off

[GreyBird]

Hi,

I mixed the Recipe "Old Gold Albany" I found somewhere probably on the web... don't remember where.

It is:

Albany Slip: 78%
Lith Carb.: 10%
Zircopax: 12%

I love the way it looks on my Hazelnut Stoneware but it flakes off on the top edge (See images - top of tile) .
Any ideas why it does this and how I might fix it?

Thanks!
-Mary

 

[Min]

It's shivering, the glaze is under compression and doesn't fit the clay. It's the opposite of crazing, you need to raise the expansion of the glaze. 10% lithium is a heck of a lot and will be causing this. Part of the lithium needs to be replaced with a higher expansion flux. There are a few different ways you could go here, would take some testing but I'ld start with dropping the lithium to 5 and adding Nepheline Syenite, up to about 10. Be prepared for the glaze to look a bit different as the fluxes used can alter the appearance of the glaze.

[Mark C.]

Shivering is really nasty-it can shiver later on as well.So all is not well with other pots with this glaze and clay even if they look good today.

If this is on functional work destroy the stuff as its a hazard down the road to whomever uses it

[GreyBird]

8 hours ago, Mark C. said:

Shivering is really nasty-it can shiver later on as well.So all is not well with other pots with this glaze and clay even if they look good today.

If this is on functional work destroy the stuff as its a hazard down the road to whomever uses it

Thanks for the warning, I haven't used it on anything because of this issue so no worries at all.

[GreyBird]

11 hours ago, Min said:

It's shivering, the glaze is under compression and doesn't fit the clay. It's the opposite of crazing, you need to raise the expansion of the glaze. 10% lithium is a heck of a lot and will be causing this. Part of the lithium needs to be replaced with a higher expansion flux. There are a few different ways you could go here, would take some testing but I'ld start with dropping the lithium to 5 and adding Nepheline Syenite, up to about 10. Be prepared for the glaze to look a bit different as the fluxes used can alter the appearance of the glaze.

Thank You! I will fix it and post results

[Min]

If you have frit 3110 I would try that also,  reduce the lithium carbonate to at least 5 and adding up to 10 of the 3110. Apply the glaze thickly on the rim of the test tiles.

[GreyBird]

50 minutes ago, Min said:

If you have frit 3110 I would try that also,  reduce the lithium carbonate to at least 5 and adding up to 10 of the 3110. Apply the glaze thickly on the rim of the test tiles.

Is the Frit 3110 in place of Neph Sy? or in addition to. And if it is in place of, is there any benefit to using it over Neph Sy?

[Min]

2 hours ago, GreyBird said:

Is the Frit 3110 in place of Neph Sy? or in addition to. And if it is in place of, is there any benefit to using it over Neph Sy?

3110 instead of Neph Sy, I'ld run tests with both. The 3110 has a higher COE (coefficient of expansion or sometimes called coefficient of thermal expansion) so it will raise the COE of the glaze more than Neph Sy will. One might look better than the other or the 3110 might actually be too high a COE and cause crazing, don't know until you run some tests.

I don't know how much you have done this type of tinkering before so apologies if you already know this but to do this testing quickly and to get as much info as you can from it this is how I would suggest doing your tests:

Mix up glaze 1 as 78 Albany plus 5 lithium carb plus 12 zirco plus 5 Neph Sy. Dip a test tile and double dip the top of it. To the same container of glaze 1 add another 5 Neph Sy and dip a second test tile, double dip the top.

Mix up glaze 2 as 78 Albany plus 5 lithium carb plus 12 zirco plus 5 ferro 3110. Dip a test tile, double dip the top. To the same container of glaze add 5 ferro 3110 and dip a second tile, double dip the top.

Since you already have those 2 glazes mixed up I would then take equal parts of both of them, just by volume is fine, mix them together and try this third new glaze.

Take your best result and before using it on real pots make a very thin walled cylinder, it can be just a thin slab or thrown, doesn't matter but make it thin then glaze the inside plus the rim very thickly with glaze. Get it on as thick as you can without it crawling (cracks while drying will be crawling when fired) and fire it. Freeze it then pour boiling water into it and see what happens.

[GreyBird]

3 minutes ago, Min said:

3110 instead of Neph Sy, I'ld run tests with both. The 3110 has a higher COE (coefficient of expansion or sometimes called coefficient of thermal expansion) so it will raise the COE of the glaze more than Neph Sy will. One might look better than the other or the 3110 might actually be too high a COE and cause crazing, don't know until you run some tests.

I don't know how much you have done this type of tinkering before so apologies if you already know this but to do this testing quickly and to get as much info as you can from it this is how I would suggest doing your tests:

Mix up glaze 1 as 78 Albany plus 5 lithium carb plus 12 zirco plus 5 Neph Sy. Dip a test tile and double dip the top of it. To the same container of glaze 1 add another 5 Neph Sy and dip a second test tile, double dip the top.

Mix up glaze 2 as 78 Albany plus 5 lithium carb plus 12 zirco plus 5 ferro 3110. Dip a test tile, double dip the top. To the same container of glaze add 5 ferro 3110 and dip a second tile, double dip the top.

Since you already have those 2 glazes mixed up I would then take equal parts of both of them, just by volume is fine, mix them together and try this third new glaze.

Take your best result and before using it on real pots make a very thin walled cylinder, it can be just a thin slab or thrown, doesn't matter but make it thin then glaze the inside plus the rim very thickly with glaze. Get it on as thick as you can without it crawling (cracks while drying will be crawling when fired) and fire it. Freeze it then pour boiling water into it and see what happens.

Thank You, I have done experimenting but not with any guidance so this is VERY helpful to me!