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On 3/16/2019 at 8:54 PM, Magnolia Mud Research said:

The wax is just an adhesive to hold the alumina in place.  The wax burns away. 

LT

...leaving a fine coating of alumina, which can be brushed or washed off after firing. A sufficient coating of alumina is what prevents sticking.

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  • 11 months later...

Hi all, this thread has saved my sanity and I have been using alumina hydrate for a while now. I don't normally wax my pots, so I just paint it on, mixed with water.  Sometimes it can be difficult to totally remove the alumina after firing. I'm wondering if anyone has experienced this issue and has any suggestions. Thanks! Amanda

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Hi Amanda and welcome to the forum :)

Alumina hydrate is not known for being difficult to remove, it just dusts right off. I'm wondering if you're getting a bit of glaze on it, where are you using it, on lid galleries or ? Also, you're 100% sure it's alumina hydrate and not something else?

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7 minutes ago, Min said:

Hi Amanda and welcome to the forum :)

Alumina hydrate is not known for being difficult to remove, it just dusts right off. I'm wondering if you're getting a bit of glaze on it, where are you using it, on lid galleries or ? Also, you're 100% sure it's alumina hydrate and not something else?

Eh it seems to stain my red clay with a dusty white that doesn't come off, I have to use sandpaper.

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Hi Min, and thanks! Long time reader, first time poster. There is a 100% chance that something has contaminated my jar. I'll mix some pure tonight. (There are lots of plates to fire.)

I use it for the bottoms of bmix and porcelain pots to prevent plucking. 

5 hours ago, liambesaw said:

Eh it seems to stain my red clay with a dusty white that doesn't come off, I have to use sandpaper.

I used just lightest dusting this time. I sanded the bottom of my plate and still had to wash it off. I swear there are still faint brush marks on the porcelain.

It's not residual glaze, but I had wondered if that was the problem.

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10 hours ago, Ceramicheights said:

I use it for the bottoms of bmix and porcelain pots to prevent plucking. 

Might want to think about your kiln wash too. If Bmix is plucking I'm thinking your kiln wash might need a re-coat. Do you make your own kiln wash (which recipe?) or use commercial stuff? 

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  • 2 weeks later...
On 3/2/2020 at 7:21 PM, liambesaw said:

Eh it seems to stain my red clay with a dusty white that doesn't come off, I have to use sandpaper.

I use a cone six red clay and it comes right off. However when I use it in cone 10 that sometimes happens. I think your clay may be over firing if the alumina gets embedded in the clay. I still use it in cone 10 but I know I will have more clean up and finishing later when I do. 

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3 minutes ago, douglas said:

I use a cone six red clay and it comes right off. However when I use it in cone 10 that sometimes happens. I think your clay may be over firing if the alumina gets embedded in the clay. I still use it in cone 10 but I know I will have more clean up and finishing later when I do. 

My red body is very fluxy, it plucks on the shelves too

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On 3/3/2020 at 8:52 AM, Min said:

Might want to think about your kiln wash too. If Bmix is plucking I'm thinking your kiln wash might need a re-coat. Do you make your own kiln wash (which recipe?) or use commercial stuff? 

Hi Min, I stopped using kiln wash a while back. It seemed to only be good the first couple of firings and then would start flaking off.  It was a kiln wash mix from my clay supplier.  It seems easier to grind the shelves than to repaint the kiln wash, and now I can flip the shelves and I've been doing it for a number of years. I do think that when the shelves get nasty, they reek havok on all my pots, not just bmix and porcelain.

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7 hours ago, Ceramicheights said:

Hi Min, I stopped using kiln wash a while back. It seemed to only be good the first couple of firings and then would start flaking off.  It was a kiln wash mix from my clay supplier.  It seems easier to grind the shelves than to repaint the kiln wash, and now I can flip the shelves and I've been doing it for a number of years. I do think that when the shelves get nasty, they reek havok on all my pots, not just bmix and porcelain.

Much of the commercial kiln wash is made up of what is cheapest, ie silica and kaolin and little of what makes a good kiln wash expensive which would be the alumina hydrate. If you do decide to start using kiln wash then try making your own wash. 50% alumina hydrate, 25% calcined kaolin and 25% kaolin. 

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