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I have made my own black stains with the same bodies of porcelain I’m using ( Audrey Blackman & Parien )They fire up to 1240 degs ( one fire )

My problem is the stained surface   ALL have blisters

Any suggestions on how I can resolve this issue ? Is there mayb something else I should be adding aside from porcelain body stain and water 

( which I then pass through a mesh sieve) Commercial stains seem fine

Would appreciate input

Kind regards Nicky

2D633366-559C-451D-8880-8749E5F6F828.jpeg

Edited by Nicky S

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I would say it's from the oxides used in the stain which are gassing off oxygen. Since commercial stains are already fired they don't off-gas like this therefore no blisters.

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23 hours ago, CactusPots said:

I'd like to know how to create that affect.  I could use it on my stuff.  I've gotten something like that occasionally, but would like to use it deliberately. 

 

23 hours ago, CactusPots said:

I'd like to know how to create that affect.  I could use it on my stuff.  I've gotten something like that occasionally, but would like to use it deliberately. 

 

23 hours ago, CactusPots said:

I'd like to know how to create that affect.  I could use it on my stuff.  I've gotten something like that occasionally, but would like to use it deliberately. 

@CactusPotsWish I could help As I said just mixed stain with porcelain clay body

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23 hours ago, Min said:

I would say it's from the oxides used in the stain which are gassing off oxygen. Since commercial stains are already fired they don't off-gas like this therefore no blisters.

@MinThank you 

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23 hours ago, Min said:

I would say it's from the oxides used in the stain which are gassing off oxygen. Since commercial stains are already fired they don't off-gas like this therefore no blisters.

If they were the result of off-gassing, wouldn't they be hollow?

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Ideally, you need to be weighing out your ingredients. If you're just eyeballing it, you could definitely be using too much stain. Dry out some clay, or trimmings, and use that for making your colored slip. I'd run some tests starting with 5% stain and going up in 5% increments until you get the color you want. You'll save yourself a lot of headaches that way, and it will be repeatable when you need to make more.

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1 hour ago, Nicky S said:

I did weigh things out 20 % slip 5% stain

Just to clarify, if the slip part of your recipe is dry porcelain that would be 100 then the stain you mixed up would be 20? I'm not getting how you have 20% slip plus 5% stain, whats the rest of it to make up the 100%? If it is indeed 20 stain you are adding to a 100 base then that amount could probably be cut way back. Somewhere between 5 - 10 should give you black. Depending on which materials you are using to make the stain, look up when the LOI occurs for each of the materials you are using in your stain mix, for example manganese dioxide is 1080C. When firing try really slowing down the firing during the range of the lowest and highest oxygen disassociation. 

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1 hour ago, Nicky S said:

@neilestrickHi Neil thank you for your input I did weigh things out 20 % slip 5% stain :-(

Nicky-

I’m not understanding something in your statement above. You say you weighed 20% slip. 20% of what? 

Usually, your dried out slip should equal 100% of your recipe, and to that you would add 5% stain. For example, if you have 200 grams of dried slip, you would then add 10 grams of stain (5% of the base) to it, mix it up with water and test. The next increment that Neil suggested was (10% of base) or 20 grams to the 200 grams of dried slip. And on until you reach your target color.

Regards,

Fred

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You stated that the blisters were solid.  How large are the blisters relative to the openings in the sieve?   Crush several of the blisters to see what is inside the blister.  I suspect that you have either porcelain lumps covered with black stain uniformly distributed over the lump, or you have lumps of stain particles.  

When I add small amounts of dry solids into slip that I would prefer not be clumped together, I will pre-wet the solids into a thick slurry before adding them to the slip.  I also blend the final slip vigorously in with a power blender until I can see and feel that all solids are uniformly distributed.    
 

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On 5/1/2019 at 6:39 PM, Fred Sweet said:

Nicky-

I’m not understanding something in your statement above. You say you weighed 20% slip. 20% of what? 

Usually, your dried out slip should equal 100% of your recipe, and to that you would add 5% stain. For example, if you have 200 grams of dried slip, you would then add 10 grams of stain (5% of the base) to it, mix it up with water and test. The next increment that Neil suggested was (10% of base) or 20 grams to the 200 grams of dried slip. And on until you reach your target color.

 Regards,

Fred

@Magnolia Mud Research

Thank you that is what  I meant re measurements Again blisters is mayb not the right word as they are solid I have posted a picture not sure if you have seen it As I pass thru an 80 mesh They are much larger I’m very  careful on mixing and measuring So don’t  think the problem  is there  :-)  I  Might have to resort to commercial Kind regards Nicky 

Edited by Nicky S

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