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Foam and Grit


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#1 Nelly

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Posted 31 March 2013 - 03:56 PM

Dear All,

I had my pottery supplier make me a batch of this Arbuckle Majolica Glaze.

When I mixed it as normal (in a brand new rubber made garbage container), I noticed foam on the top that did not dissipate until sieved through the talisman. I also noticed significant grit on my screen??

Here are my questions:

1. Why the foam?? I haven't seen this before to such an extent. It was as though I was cooking lentils or navy beans (i.e., the foam that developed). Know that once it went through the talisman it appears to have dissipated. I will, of course, sieve it again in a few days giving it yet more time to settle. The foam just made me really curious. Why the foam??

2. What in my recipe would cause this grit to be left behind on my screen despite being well mixed??


Here is the recipe:


Majolica Glaze
Cone 04 Oxidation Glaze Material
Percentage Frit 3124 (Ferro) 65.72% Kona F-4 Feldspar 17.23 Nepheline Syenite 6.24 Edgar Plastic Kaolin 10.81 Total 100.0% Add:
Tin Oxide 5.00% Zircopax 10.00 Bentonite 2.00

If anyone has any experience with this glaze, can you let me know your idea for the reason for the foam and what the particles are left behind on my fine mesh screen. Please know that while these were left behind, I still dumped um back into the freshly sieved glaze as I intend to do it again at least one more time.

Thank you in advance,

Nelly

#2 bciskepottery

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Posted 31 March 2013 - 08:59 PM

What mesh screen are you sieving at? Tin oxide can be coarse. Could there have been some type of film/oil/ or other residue in the new plastic bucket?

#3 JBaymore

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Posted 31 March 2013 - 09:03 PM

I've noted lately that EPK can have some "crap" in it.

best,

..............john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#4 Nelly

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Posted 31 March 2013 - 09:08 PM

I've noted lately that EPK can have some "crap" in it.

best,

..............john


Dear All,

I am not sure of my mesh screen size. I am guessing when I ordered it that it would be something in between. Not too small but not too open. Thus, maybe it is the Tin?? I could see the particles.

And maybe it was the EPK??

I did use a towel to really wipe out the inside of my bucket but you never know...maybe there was some residual plastic goo on the inside.

It looks fine now that it has been sieved but there was definitely some foam that I have never seen in other glazes I have made.

Thank you both.

Nancy

#5 TJR

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Posted 31 March 2013 - 09:19 PM


I've noted lately that EPK can have some "crap" in it.

best,

..............john


Dear All,

I am not sure of my mesh screen size. I am guessing when I ordered it that it would be something in between. Not too small but not too open. Thus, maybe it is the Tin?? I could see the particles.

And maybe it was the EPK??

I did use a towel to really wipe out the inside of my bucket but you never know...maybe there was some residual plastic goo on the inside.

It looks fine now that it has been sieved but there was definitely some foam that I have never seen in other glazes I have made.

Thank you both.

Nancy

Nancy;
It should say the mesh size on the side of your sieve. The "size" represents the number of screen holes per square inch. So for an 80 mesh sieve, you would have 80 holes per square inch. I usually sieve my glazes with an 80 mesh into a clean bucket, and then back into the original [cleaned] bucket with an100 mesh sieve. Low fire glazes melt better with a smaller particle size. The only glazes that I sieve through a coarser mesh would be ash glazes, at 40 mesh. Sometimes you get gases with colemanite or bone ash, neither of which were in your glaze.
TJR.

#6 Nelly

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Posted 31 March 2013 - 09:59 PM



I've noted lately that EPK can have some "crap" in it.

best,

..............john


Dear All,

I am not sure of my mesh screen size. I am guessing when I ordered it that it would be something in between. Not too small but not too open. Thus, maybe it is the Tin?? I could see the particles.

And maybe it was the EPK??

I did use a towel to really wipe out the inside of my bucket but you never know...maybe there was some residual plastic goo on the inside.

It looks fine now that it has been sieved but there was definitely some foam that I have never seen in other glazes I have made.

Thank you both.

Nancy

Nancy;
It should say the mesh size on the side of your sieve. The "size" represents the number of screen holes per square inch. So for an 80 mesh sieve, you would have 80 holes per square inch. I usually sieve my glazes with an 80 mesh into a clean bucket, and then back into the original [cleaned] bucket with an100 mesh sieve. Low fire glazes melt better with a smaller particle size. The only glazes that I sieve through a coarser mesh would be ash glazes, at 40 mesh. Sometimes you get gases with colemanite or bone ash, neither of which were in your glaze.
TJR.


Dear John,

I will write you last message down. 80 then 100 mesh. Only use large mesh with ash glazes. Simple formula but important need to know information.

Please know I have picked up my screen from downstairs and notice no where on the talisman screen is there a number. I am pretty sure, in looking at the Tuckers site and knowing how I think, I would have asked them first and then went for the medium or 100 mesh. Thus, I am guessing what I did this afternoon was sieve through my one and only mesh disc--100 size. Given the amount of grit I saw in the sieve I knew it was important stuff to keep in the glaze. Thus, I dumped it back in and when I do a second or third sieving I will decide what is junk from important particle.

Nelly

#7 TJR

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Posted 01 April 2013 - 08:52 AM




I've noted lately that EPK can have some "crap" in it.

best,

..............john


Dear All,

I am not sure of my mesh screen size. I am guessing when I ordered it that it would be something in between. Not too small but not too open. Thus, maybe it is the Tin?? I could see the particles.

And maybe it was the EPK??

I did use a towel to really wipe out the inside of my bucket but you never know...maybe there was some residual plastic goo on the inside.

It looks fine now that it has been sieved but there was definitely some foam that I have never seen in other glazes I have made.

Thank you both.

Nancy

Nancy;
It should say the mesh size on the side of your sieve. The "size" represents the number of screen holes per square inch. So for an 80 mesh sieve, you would have 80 holes per square inch. I usually sieve my glazes with an 80 mesh into a clean bucket, and then back into the original [cleaned] bucket with an100 mesh sieve. Low fire glazes melt better with a smaller particle size. The only glazes that I sieve through a coarser mesh would be ash glazes, at 40 mesh. Sometimes you get gases with colemanite or bone ash, neither of which were in your glaze.
TJR.


Dear John,

I will write you last message down. 80 then 100 mesh. Only use large mesh with ash glazes. Simple formula but important need to know information.

Please know I have picked up my screen from downstairs and notice no where on the talisman screen is there a number. I am pretty sure, in looking at the Tuckers site and knowing how I think, I would have asked them first and then went for the medium or 100 mesh. Thus, I am guessing what I did this afternoon was sieve through my one and only mesh disc--100 size. Given the amount of grit I saw in the sieve I knew it was important stuff to keep in the glaze. Thus, I dumped it back in and when I do a second or third sieving I will decide what is junk from important particle.

Nelly

Nancy;
It's Tom. It's a lot easier to sieve through a coarser screen first. I use a big variable speed drill with a plaster propeller[Home Depot or Rona], Sometimes I let the wet glaze sit over night. I go coarse sieve first, then the finer sieve. You could take your sieve back to Tuckers, and compare with what they have.I also use one of those shower back brushes to work the gunk through. Saves my finger tips. My back brush is pink for some reason. Garage sale find. Imagine selling a back brush at a garage sale?
TJR.Posted Image




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